Packaged Rooftop Units

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−---

−title: Packaged Rooftop Units

−category: Mechanical / Air Distribution

−toc_depth: 3

−description: >

− When to use: Factory-assembled, self-contained packaged rooftop units (RTUs) with integral direct-expansion (DX) refrigerant cooling, mounted on a roof curb and serving a ducted distribution system. Covers single-zone constant-volume, multi-zone, and variable-air-volume (VAV) configurations; gas-fired, electric resistance, heat pump, and hydronic heating options; air-side economizers; outdoor-air ventilation and demand-controlled ventilation; and capacities from approximately 3 tons through large rooftop units above 60 tons. Applicable to commercial, institutional, and light-industrial buildings.

− Not intended for: Central station air handling units served by a chilled water and hot water plant (see [[sync/air-handling-units]]); dedicated outdoor air systems and split-system equipment with remote condensing units; chillers and the hydronic plant ([[sync/chillers]]); ductwork beyond the unit connections ([[sync/hvac-ductwork]]); air distribution devices and VAV terminal units downstream of the unit ([[sync/air-terminal-units]]); variable frequency drives applied as separate components ([[sync/hvac-variable-frequency-drives]]); testing, adjusting, and balancing after installation ([[sync/testing-adjusting-and-balancing]]); and building automation system controls integration ([[sync/building-automation-system]]).

−---

−

−# Scope {toc}

−

−## This specification covers factory-assembled, self-contained packaged rooftop units (RTUs) with integral direct-expansion refrigerant cooling, mounted on a roof curb and connected to a ducted air distribution system. {note}

−## Equipment covered includes the cabinet, compressors and refrigerant circuits, air-cooled condenser coil and condenser fans, indoor DX evaporator (cooling) coil, supply fan and motor, integral heating section, outdoor-air and economizer dampers, filtration, condensate management, unit-mounted controls, and the roof curb and vibration isolation interface. {note}

−

−## A packaged rooftop unit is distinguished from a central station air handler by its integral, factory-charged refrigerant system contained within a single weatherproof cabinet, eliminating the field-installed chilled water plant and the associated hydronic piping. {note}

−

−## Equipment shall comply with ANSI/AHRI 340/360 for performance rating of commercial and industrial unitary equipment (65,000 Btu/h and above), ANSI/AHRI 210/240 for unitary equipment below 65,000 Btu/h, ANSI/ASHRAE/IES 90.1 for energy efficiency and economizer requirements, ANSI/ASHRAE 62.1 for outdoor-air ventilation, ANSI/ASHRAE 15 and ANSI/ASHRAE 34 for refrigerant safety and classification, ANSI Z21.47 / CSA 2.3 for gas-fired heating sections, NFPA 90A for fire and smoke safety, and UL 60335-2-40 for electrical and refrigerant-system safety listing.

−

−## The Contractor shall coordinate RTU installation with the roof curb and structural roof framing, the roofing and flashing system, ductwork connections through the curb, electrical power and control wiring, gas piping (where gas heat is provided), condensate drainage, and vibration isolation.

−

−## Coordination with [[sync/building-automation-system]] is required for controls integration, and ductwork shall conform to [[sync/hvac-ductwork]].

−

−# Referenced Standards {toc}

−

−## Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.

−

−| Standard | Title |

−|----------|-------|

−| ANSI/AHRI 340/360 (I-P) | Performance Rating of Commercial and Industrial Unitary Air-conditioning and Heat Pump Equipment |

−| ANSI/AHRI 210/240 | Performance Rating of Unitary Air-conditioning and Air-source Heat Pump Equipment (below 65,000 Btu/h) |

−| ANSI/ASHRAE/IES 90.1 | Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings |

−| ANSI/ASHRAE 62.1 | Ventilation and Acceptable Indoor Air Quality |

−| ANSI/ASHRAE 15 | Safety Standard for Refrigeration Systems |

−| ANSI/ASHRAE 34 | Designation and Safety Classification of Refrigerants |

−| ANSI/ASHRAE 52.2 | Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size |

−| UL 60335-2-40 | Safety of Household and Similar Electrical Appliances — Particular Requirements for Electrical Heat Pumps, Air-Conditioners, and Dehumidifiers |

−| UL 1995 | Heating and Cooling Equipment (where accepted by the AHJ in lieu of UL 60335-2-40) |

−| ANSI Z21.47 / CSA 2.3 | Gas-Fired Central Furnaces (applicable to gas-fired heating sections) |

−| ANSI/AMCA 210 / ASHRAE 51 | Laboratory Methods of Testing Fans for Certified Aerodynamic Performance Rating |

−| ANSI/AMCA 300 | Reverberation Room Methods of Sound Testing of Fans |

−| NFPA 90A | Standard for the Installation of Air-Conditioning and Ventilating Systems |

−| NFPA 70 (NEC) | National Electrical Code |

−| IMC | International Mechanical Code, adopted edition |

−| IECC | International Energy Conservation Code, adopted edition |

−| ASCE 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures |

−| SMACNA | HVAC Duct Construction Standards — Metal and Flexible |

−| EPA AIM Act / 40 CFR Part 84 | American Innovation and Manufacturing Act — HFC phasedown and refrigerant transition rules |

−

−## Where conflicts exist between referenced standards, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

−

−# Submittals {toc}

−

−## Action Submittals {toc}

−

−### Contractor shall submit the following for review and acceptance prior to ordering equipment; fabrication and procurement shall not proceed until action submittals have been reviewed and returned.

−

−- Manufacturer's product data for each RTU, including model designation, configuration, capacity ratings, and a unit weight and dimensional drawing showing the roof curb interface, supply and return openings, and required service clearances

−- Certified performance data per AHRI 340/360 (or AHRI 210/240 for units below 65,000 Btu/h), including net total and sensible cooling capacity at design conditions, EER, IEER, and heating capacity and efficiency

−- Refrigerant designation, ASHRAE 34 safety classification, total factory charge by circuit, and, for A2L refrigerants, the calculated charge limit and the leak-detection and mitigation provisions per UL 60335-2-40

−- Supply fan performance data at the design external static pressure, including fan brake horsepower and ASHRAE 90.1 fan-power compliance documentation

−- Compressor data including type, number of stages or capacity-modulation range, and minimum step of unloading

−- Heating section data: for gas heat, input and output capacity, turndown, and ANSI Z21.47 certification; for electric heat, kW and stage count; for heat pump, integrated heating capacity and supplemental heat

−- Economizer assembly data including damper leakage class, actuator type, changeover control method, and FDD provisions per ASHRAE 90.1

−- Sound power level data per AMCA 300 in octave bands, for both supply discharge and outdoor (condenser) radiated sound

−- Roof curb drawing showing curb height, dimensions, gasketing, supply and return duct openings, and the curb-to-unit interface; seismic and wind restraint details where required

−- Electrical data including unit minimum circuit ampacity (MCA), maximum overcurrent protection (MOCP), voltage, phase, and disconnect configuration

−- Filter data including MERV rating certification per ASHRAE 52.2 and rack configuration

−

−```datasheet

−label: Action Submittals Required

−type: checkbox

−options:

− - "Product data, dimensional and weight drawing, clearances"

− - "AHRI certified performance data (cooling, EER, IEER, heating)"

− - "Refrigerant type, charge, and A2L leak-detection provisions"

− - "Supply fan performance and ASHRAE 90.1 fan-power compliance"

− - "Compressor staging / modulation data"

− - "Heating section data and gas/electric/heat-pump certification"

− - "Economizer and FDD data"

− - "Sound power levels (AMCA 300)"

− - "Roof curb drawing and restraint details"

− - "Electrical data (MCA, MOCP, voltage, disconnect)"

− - "Filter MERV certification (ASHRAE 52.2)"

−default: "Product data, dimensional and weight drawing, clearances"

−```

−

−## Closeout Submittals {toc}

−

−### Contractor shall provide the following at or before substantial completion:

−

−- Operation and maintenance manuals with manufacturer's installation, operation, and maintenance instructions for the unit and all major components

−- As-built wiring diagrams and the BAS points list with terminal designations

−- Factory and field test reports, including the startup report by the manufacturer's representative

−- Refrigerant charge record (type, total charge by circuit, and any field charge adjustment)

−- Commissioning records, including economizer and FDD functional test results

−- Air balance report from the TAB agent per [[sync/testing-adjusting-and-balancing]]

−- Filter media installed at substantial completion with MERV certification and a change-out date tag

−- Warranty documentation, including the separate compressor and heat exchanger warranties

−

−```datasheet

−label: Required Closeout Submittals

−type: checkbox

−options:

− - "Operation and maintenance manuals"

− - "As-built wiring diagrams and BAS points list"

− - "Factory and field test reports including startup report"

− - "Refrigerant charge record"

− - "Commissioning records (economizer and FDD functional tests)"

− - "Air balance report from TAB agent"

− - "Filter media with MERV certification and change-out date tag"

− - "Warranty documentation (including compressor and heat exchanger)"

−default: "Operation and maintenance manuals"

−```

−

−# Quality Assurance {toc}

−

−## Manufacturer Qualifications {toc}

−

−### RTUs shall be produced by a manufacturer regularly engaged in the production of packaged unitary equipment for a minimum of ten years, with a documented quality management system.

−

−### The manufacturer shall provide the capability to supply replacement parts and factory-authorized service within the project region for a minimum of fifteen years after the date of manufacture.

−

−## AHRI Certification {toc}

−

−```datasheet

−label: AHRI Certification Basis

−type: radio

−options:

− - "AHRI 340/360 (units 65,000 Btu/h and above)"

− - "AHRI 210/240 (units below 65,000 Btu/h)"

−default: "AHRI 340/360 (units 65,000 Btu/h and above)"

−```

−

−### Units rated 65,000 Btu/h and above shall be certified under the AHRI Unitary Large Equipment (ULE) or applicable certification program to AHRI 340/360, and published EER and IEER ratings shall bear the AHRI certification mark.

−

−### Units below 65,000 Btu/h shall be certified to AHRI 210/240.

−

−### Published capacities and efficiency ratings shall reflect AHRI-certified ratings, not uncertified catalog selections.

−

−## NRTL Listing {toc}

−

−### The complete unit, including all electrical and refrigerant-system components, shall be listed and labeled by a Nationally Recognized Testing Laboratory (NRTL) to UL 60335-2-40.

−

−### Where the AHJ continues to accept UL 1995 listings for equipment manufactured before the transition date, UL 1995-listed equipment is acceptable.

−

−### Gas-fired heating sections shall additionally be certified to ANSI Z21.47 / CSA 2.3.

−

−## Pre-Installation Conference {toc}

−

−### A pre-installation conference shall be held before setting any RTU, attended by the Contractor, the roofing sub-contractor, the controls sub-contractor, the TAB agent, and the Owner's representative.

−

−### The agenda shall include crane and rigging plan, curb setting and flashing sequence, structural load verification, utility connections, refrigerant A2L safety provisions, controls interface points, and the commissioning schedule.

−

−# Environmental and Service Conditions {toc}

−

−## RTUs shall be selected and rated for the operating conditions at the installation site.

−## Design conditions are [[drawing: as indicated on the mechanical schedules]]. {note}

−

−## Because the entire unit, including compressors and the condenser, is exposed to outdoor weather, the cabinet, coatings, and components shall be suitable for continuous outdoor service.

−

−## Ambient Operating Range {toc}

−

−```datasheet

−label: Low-Ambient Mechanical Cooling

−type: select

−options:

− - "Not required — economizer provides cooling below 55°F outdoor"

− - "Condenser fan cycling — to approximately 35°F outdoor"

− - "Condenser fan speed control — to approximately 0°F outdoor"

− - "Low-ambient head-pressure control — below 0°F outdoor"

−default: "Not required — economizer provides cooling below 55°F outdoor"

−```

−

−### The unit shall provide rated mechanical cooling at outdoor ambient temperatures up to 115°F and shall be capable of operation at the design summer ambient for the project climate zone.

−

−### Where mechanical cooling is required at outdoor temperatures below 55°F (e.g., to serve interior loads in cold weather), low-ambient cooling provisions such as condenser fan cycling, condenser fan speed control, or head-pressure control shall be specified.

−

−## Corrosive and Coastal Environments {toc}

−

−```datasheet

−label: Coil Corrosion Protection

−type: select

−options:

− - "Standard — uncoated aluminum fin / copper tube"

− - "E-coat (epoxy) applied coil — coastal and industrial"

− - "Microchannel aluminum with protective coating"

− - "Copper fin / copper tube"

−default: "Standard — uncoated aluminum fin / copper tube"

−```

−

−### Where the unit is installed within approximately three miles of a saltwater coast, or in an industrial atmosphere with corrosive contaminants, the condenser and evaporator coils shall be protected with a corrosion-resistant coil treatment and the cabinet exterior shall receive an enhanced corrosion-resistant finish.

−

−### Uncoated aluminum-fin condenser coils corrode rapidly in salt-laden air, reducing heat rejection and shortening compressor life. {note}

−

−# Performance and Efficiency {toc}

−

−## Cooling Capacity {toc}

−

−```datasheet

−label: Nominal Cooling Capacity

−type: range

−unit: tons

−drawing_ref: true

−options:

− min: 3

− max: 150

− setpoints: [3, 4, 5, 6, 7.5, 10, 12.5, 15, 20, 25, 30, 40, 50, 60, 75, 100, 150]

−default: 20

−```

−

−### Net total and net sensible cooling capacity at the design entering conditions shall be [[drawing: as indicated on the mechanical schedules]].

−

−### Capacity shall be the net value after deduction of supply fan heat, certified per AHRI 340/360.

−

−### Sensible heat ratio shall be appropriate for the space load; selecting a unit by total capacity alone, without confirming sensible capacity, is a common cause of poor humidity control in spaces with high latent load.

−

−## Efficiency Ratings {toc}

−

−```datasheet

−label: Cooling Efficiency Compliance Basis

−type: radio

−options:

− - "ASHRAE 90.1 minimum EER and IEER"

− - "IECC minimum EER and IEER"

− - "Exceeds code minimum — life-cycle optimized (project goal)"

−default: "ASHRAE 90.1 minimum EER and IEER"

−```

−

−```datasheet

−label: Minimum Full-Load Efficiency (EER)

−type: range

−unit: EER

−options:

− min: 9.5

− max: 14

− step: 0.1

−default: 11

−```

−

−```datasheet

−label: Minimum Part-Load Efficiency (IEER)

−type: range

−unit: IEER

−options:

− min: 11

− max: 20

− step: 0.1

−default: 14

−```

−

−### Cooling efficiency shall meet or exceed the minimum EER and IEER required by ASHRAE 90.1 (or the adopted IECC) for the unit's capacity category and heating type.

−

−### Units below 65,000 Btu/h are additionally rated by SEER2 and EER2 per AHRI 210/240.

−

−### Selections that exceed the code minimum should be evaluated on life-cycle cost where energy rates or operating hours are high.

−

−### Integrated Energy Efficiency Ratio (IEER) represents weighted part-load performance across four load points and is the controlling metric for most commercial RTUs, which spend the majority of operating hours at part load. {note}

−

−# Refrigerant System {toc}

−

−## Refrigerant Selection {toc}

−

−```datasheet

−label: Refrigerant Type

−type: radio

−options:

− - "R-454B (A2L, low-GWP) — current commercial standard"

− - "R-32 (A2L, low-GWP)"

− - "R-410A (legacy — existing-equipment replacement only)"

−default: "R-454B (A2L, low-GWP) — current commercial standard"

−```

−

−### Specifying R-410A on new units is no longer aligned with current production and should be limited to replacement components for existing equipment.

−

−### Under the EPA AIM Act HFC phasedown, new packaged unitary equipment manufactured for the US market has transitioned away from R-410A to lower-GWP A2L refrigerants such as R-454B and R-32, both of which carry an ASHRAE 34 A2L (lower-toxicity, lower-flammability) classification and a global warming potential substantially below R-410A. {note}

−

−## A2L Safety Provisions {toc}

−

−```datasheet

−label: A2L Leak Detection and Mitigation

−type: radio

−options:

− - "Factory-installed leak detector with mitigation (required above charge limit)"

− - "Not required — charge below A2L threshold for the cabinet"

− - "Not applicable — non-flammable (A1) refrigerant"

−default: "Factory-installed leak detector with mitigation (required above charge limit)"

−```

−

−### For units charged with an A2L refrigerant, the unit shall comply with the charge-limit, leak-detection, and mitigation requirements of UL 60335-2-40 and ASHRAE 15.

−

−### Where the refrigerant charge in a circuit exceeds the applicable limit, the unit shall include a factory-installed refrigerant leak detector that, on detection, initiates supply fan operation to dissipate refrigerant and de-energizes ignition sources.

−

−### The Contractor shall not field-modify A2L charge or relocate detectors.

−

−### Service personnel shall be trained for A2L equipment.

−

−## Compressor Type and Capacity Control {toc}

−

−```datasheet

−label: Compressor Capacity Control

−type: select

−options:

− - "Single-stage (one compressor, on/off)"

− - "Two-stage (staged compressors or two-step unloading)"

− - "Multi-stage (three or more capacity steps)"

− - "Variable-capacity (digital scroll or inverter-driven)"

−default: "Two-stage (staged compressors or two-step unloading)"

−```

−

−```datasheet

−label: Number of Independent Refrigerant Circuits

−type: select

−options:

− - "1 — single circuit (small units)"

− - "2 — dual circuit (redundancy and staging)"

− - "3 or more — large-capacity units"

−default: "2 — dual circuit (redundancy and staging)"

−```

−

−### Compressors shall be hermetic or semi-hermetic scroll type.

−

−### Each refrigerant circuit shall be independent, with its own compressor, expansion device, and condenser section, so a single circuit failure does not disable all cooling.

−

−### Capacity control determines part-load efficiency and comfort: single-stage compressors cycle fully on and off, multiple staged compressors provide stepped capacity, and variable-capacity (digital scroll or inverter) compressors modulate continuously to match load, with variable-capacity compression delivering the highest part-load efficiency at higher first cost while staged compression remains the common choice for most commercial applications. {note}

−

−# Heating {toc}

−

−## Heating Source {toc}

−

−```datasheet

−label: Heating Source

−type: select

−options:

− - "Gas-fired (natural gas)"

− - "Gas-fired (propane / LP)"

− - "Electric resistance"

− - "Heat pump (reverse-cycle) with supplemental electric heat"

− - "Hydronic hot water coil"

− - "Cooling only — no integral heat"

−default: "Gas-fired (natural gas)"

−```

−

−### The integral heating source shall be selected for the building's heating load, available fuel, and energy strategy.

−

−### Gas-fired heating is the most common selection for commercial RTUs where natural gas is available; electric resistance heat is used where gas is unavailable or for small heating loads; heat pump (reverse-cycle) units provide efficient heating above the balance point and typically include supplemental electric heat for cold weather; and a hydronic heating coil allows the unit to be served by a building hot water plant where one exists. {note}

−

−## Gas-Fired Heating Section {toc}

−

−```datasheet

−label: Gas Heat Exchanger Material

−type: radio

−options:

− - "Aluminized steel — standard service"

− - "Type 409 stainless steel — extended life / condensing risk"

− - "Type 304/316 stainless steel — corrosive or high-cycling service"

−default: "Aluminized steel — standard service"

−```

−

−```datasheet

−label: Gas Burner Control

−type: select

−options:

− - "Single-stage"

− - "Two-stage"

− - "Modulating (high turndown)"

−default: "Two-stage"

−```

−

−```datasheet

−label: Heating Input Capacity

−type: range

−unit: MBH

−drawing_ref: true

−options:

− min: 50

− max: 1500

− step: 25

−default: 250

−```

−

−### Gas-fired heating sections shall be certified to ANSI Z21.47 / CSA 2.3 with a stainless steel or aluminized steel heat exchanger as specified.

−

−### Burners shall be staged or modulating to provide turndown that reduces temperature swing and short cycling.

−

−### Combustion air and flue products shall be handled per the manufacturer's listing.

−

−### The heat exchanger shall be warranted separately against failure from thermal cracking.

−

−## Electric and Heat Pump Heating {toc}

−

−```datasheet

−label: Electric / Supplemental Heat Capacity

−type: range

−unit: kW

−drawing_ref: true

−options:

− min: 5

− max: 150

− step: 5

−default: 30

−```

−

−### Electric resistance heating elements shall be staged and protected by automatic-reset and manual-reset high-limit thermal cutouts.

−

−### Heat pump units shall report the integrated heating capacity at the design heating ambient and shall include supplemental electric resistance heat sized for the balance-point shortfall and for defrost recovery.

−

−### Supplemental heat shall be locked out by the controls above the balance-point temperature to avoid unnecessary electric heating.

−

−# Economizer and Ventilation {toc}

−

−## Air-Side Economizer {toc}

−

−```datasheet

−label: Economizer

−type: select

−options:

− - "Integrated air-side economizer — modulating to 100% OA"

− - "Economizer with powered exhaust / relief fan"

− - "No economizer (only where code-exempt)"

−default: "Integrated air-side economizer — modulating to 100% OA"

−```

−

−```datasheet

−label: Economizer Changeover Control

−type: select

−options:

− - "Differential dry-bulb (OA temp below RA temp)"

− - "Fixed dry-bulb (OA below fixed high-limit setpoint)"

− - "Differential enthalpy (OA enthalpy below RA enthalpy)"

− - "Fixed enthalpy (OA enthalpy below fixed setpoint)"

−default: "Differential dry-bulb (OA temp below RA temp)"

−```

−

−### Where required by ASHRAE 90.1 Section 6.5.1 (or the adopted energy code) for the unit's capacity and climate zone, the unit shall include an integrated air-side economizer capable of modulating outdoor-air dampers to 100% outdoor air for free cooling when outdoor conditions are favorable.

−

−### The economizer shall include a barometric or powered relief path to maintain building pressure at high outdoor-air fractions.

−

−### The design team shall select the changeover strategy appropriate to the climate zone and the Owner's maintenance capability.

−

−### A low-leakage outdoor-air damper is essential: a leaky economizer damper admits unconditioned air during mechanical cooling and heating, wasting energy year-round. {note}

−

−### Differential enthalpy control captures the most economizer hours in humid climates but requires enthalpy sensors that need periodic calibration, while fixed or differential dry-bulb control is simpler and more reliable in dry climates. {note}

−

−## Economizer Fault Detection and Diagnostics {toc}

−

−```datasheet

−label: Economizer Fault Detection and Diagnostics (FDD)

−type: radio

−options:

− - "FDD with fault reporting to BAS (per ASHRAE 90.1 6.4.3.12)"

− - "FDD with local annunciation only"

− - "Not required (code-exempt unit)"

−default: "FDD with fault reporting to BAS (per ASHRAE 90.1 6.4.3.12)"

−```

−

−### Where required by ASHRAE 90.1 Section 6.4.3.12, the economizer shall include fault detection and diagnostics (FDD) capable of detecting and reporting faulty changeover sensors, damper-not-modulating conditions, excess or deficient outdoor air, and economizer-disabled-when-it-should-be-enabled conditions.

−

−### Faults shall be reported to the BAS or annunciated locally so service personnel can act on them.

−

−### Economizers without FDD are a frequent source of silent energy waste because a failed damper or sensor goes unnoticed for years. {note}

−

−## Outdoor-Air Ventilation {toc}

−

−```datasheet

−label: Minimum Outdoor-Air Control Method

−type: select

−options:

− - "Fixed minimum damper position (constant-volume units)"

− - "Outdoor-air measurement station with damper control (VAV units)"

− - "Differential-pressure / flow-station control"

−default: "Outdoor-air measurement station with damper control (VAV units)"

−```

−

−```datasheet

−label: Design Minimum Outdoor Airflow

−type: range

−unit: CFM

−drawing_ref: true

−options:

− min: 100

− max: 20000

− step: 50

−default: 2000

−```

−

−### The unit shall deliver the minimum outdoor airflow required by ASHRAE 62.1 for the served occupancy at all operating conditions, including reduced supply airflow on VAV systems.

−

−### Reliable minimum outdoor-air control on a VAV unit generally requires an outdoor-air measurement and control method rather than a fixed damper position, because the outdoor-air fraction at a fixed damper position varies with supply fan speed and building pressure. {note}

−

−## Demand-Controlled Ventilation {toc}

−

−```datasheet

−label: Demand-Controlled Ventilation (DCV)

−type: radio

−options:

− - "CO2-based DCV (required for high-density spaces per 90.1 6.4.3.8)"

− - "Occupancy-based DCV (scheduled or sensor)"

− - "Not provided (low-density occupancy)"

−default: "Not provided (low-density occupancy)"

−```

−

−### Where required by ASHRAE 90.1 Section 6.4.3.8 for densely occupied spaces, the unit shall provide demand-controlled ventilation (DCV) that resets outdoor airflow based on space CO2 concentration in proportion to actual occupancy.

−

−### DCV shall not reduce outdoor air below the area-based (base) ventilation rate required for the space.

−

−### DCV reduces the energy penalty of ventilating for peak occupancy when a space is partly occupied, while maintaining ASHRAE 62.1 ventilation per person. {note}

−

−# Supply Fan and Air Distribution {toc}

−

−## Supply Fan Type and Volume Control {toc}

−

−```datasheet

−label: Supply Fan Volume Control

−type: select

−options:

− - "Constant volume — fixed speed"

− - "Variable air volume — VFD-driven"

− - "Variable air volume — ECM (electronically commutated motor)"

− - "Two-speed"

−default: "Constant volume — fixed speed"

−```

−

−```datasheet

−label: Supply Fan Type

−type: select

−options:

− - "Forward-curved centrifugal (smaller units)"

− - "Backward-curved / airfoil centrifugal"

− - "Plenum (plug) fan — direct drive"

−default: "Forward-curved centrifugal (smaller units)"

−```

−

−### Constant-volume units shall use a fixed-speed fan and are appropriate for single-zone applications.

−

−### VAV units shall modulate supply airflow to match zone loads and shall use a variable-speed fan.

−

−### Electronically commutated motor (ECM) and variable-frequency-drive (VFD) driven fans shall deliver the part-load energy savings that ASHRAE 90.1 requires for VAV and for multi-stage units.

−

−### Forward-curved fans remain common in smaller packaged units, but backward-curved and ECM plenum fans provide higher efficiency and lower sound in larger units. {note}

−

−## Design External Static Pressure and Fan Power {toc}

−

−```datasheet

−label: Design Supply Airflow

−type: range

−unit: CFM

−drawing_ref: true

−options:

− min: 1000

− max: 60000

− step: 250

−default: 8000

−```

−

−```datasheet

−label: Design External Static Pressure

−type: range

−unit: in. w.g.

−drawing_ref: true

−options:

− min: 0.3

− max: 4.0

− setpoints: [0.3, 0.5, 0.75, 1.0, 1.25, 1.5, 2.0, 2.5, 3.0, 4.0]

−default: 1.0

−```

−

−```datasheet

−label: Supply Fan Motor Voltage

−type: select

−options:

− - "208V / 3-phase"

− - "460V / 3-phase"

− - "575V / 3-phase"

− - "208V / 1-phase (small units only)"

−default: "460V / 3-phase"

−```

−

−### Supply airflow and design external static pressure shall be [[drawing: as indicated on the mechanical schedules]].

−

−### Fan brake horsepower at design conditions shall comply with the ASHRAE 90.1 fan-power limits.

−

−### The fan shall be selected at the design point with margin for the loaded-filter condition so that the unit delivers design airflow throughout the filter service interval.

−

−# Cabinet and Construction {toc}

−

−## Cabinet Construction {toc}

−

−```datasheet

−label: Cabinet Panel Construction

−type: radio

−options:

− - "Double-wall insulated panels (foam or fiber, with inner liner)"

− - "Single-wall with internal insulation liner (small units only)"

−default: "Double-wall insulated panels (foam or fiber, with inner liner)"

−```

−

−```datasheet

−label: Cabinet Insulation R-value

−type: select

−unit: hr·ft²·°F/Btu

−options:

− - "R-4 to R-6 (standard commercial)"

− - "R-8 to R-13 (cold climate / energy-conscious)"

−default: "R-4 to R-6 (standard commercial)"

−```

−

−### The cabinet shall be weatherproof, of double-wall insulated panel construction for all conditioned-air sections, with a galvanized steel structure and a corrosion-resistant exterior finish suitable for continuous outdoor exposure.

−

−### Panels shall be insulated to limit thermal loss and surface condensation.

−

−### Double-wall construction prevents exterior sweating, protects the insulation from erosion and moisture, and improves cabinet rigidity and sound attenuation. {note}

−

−## Exterior Finish {toc}

−

−```datasheet

−label: Exterior Finish Salt-Spray Rating

−type: radio

−options:

− - "Standard — minimum 500-hour ASTM B117"

− - "Enhanced — minimum 1,000-hour ASTM B117 (coastal / industrial)"

−default: "Standard — minimum 500-hour ASTM B117"

−```

−

−### Exterior cabinet panels shall receive a factory-applied, UV-resistant, corrosion-resistant finish demonstrated to withstand a minimum 1,000-hour salt-spray exposure per ASTM B117.

−

−### Fasteners and hardware exposed to weather shall be corrosion-resistant.

−

−### All field cuts and penetrations made during installation shall receive touch-up coating.

−

−## Access Panels {toc}

−

−```datasheet

−label: Access Panel Type

−type: radio

−options:

− - "Hinged, gasketed, with quarter-turn latches"

− - "Removable bolted gasketed panels"

−default: "Hinged, gasketed, with quarter-turn latches"

−```

−

−### Hinged or removable access panels shall be provided at the filter, evaporator coil and drain pan, supply fan, compressor, and heating sections.

−

−### Panels shall be gasketed and shall seal against air leakage.

−

−### Access shall permit filter change, compressor service, and component replacement without removing the unit from the curb.

−

−## Filtration {toc}

−

−```datasheet

−label: Filter MERV Rating

−type: select

−options:

− - "MERV 8 — minimum for commercial occupied spaces"

− - "MERV 11 — improved particulate removal"

− - "MERV 13 — enhanced IAQ (recommended; code/green-building)"

−default: "MERV 13 — enhanced IAQ (recommended; code/green-building)"

−```

−

−### The unit shall include a filter section upstream of the evaporator coil with a rack sized for the specified filter.

−

−### Air filtration shall comply with ASHRAE 52.2.

−

−### The fan selection shall account for the final (loaded) filter resistance.

−

−### MERV 8 is the practical minimum for commercial occupied spaces; MERV 13 is the recommended selection for general indoor air quality where the unit fan and cabinet can accommodate the additional pressure drop, and is increasingly required by code and green-building programs. {note}

−

−## Condensate Drain Pan {toc}

−

−```datasheet

−label: Condensate Drain Pan Material

−type: radio

−options:

− - "Stainless steel"

− - "Corrosion-resistant coated steel"

− - "Molded composite / polymer"

−default: "Stainless steel"

−```

−

−### A sloped, corrosion-resistant condensate drain pan shall be provided beneath the evaporator coil, extending downstream of the coil face to capture carryover.

−

−### The pan shall fully drain after each cooling cycle to prevent the standing water that promotes biological growth.

−

−### A condensate trap sized for the negative static pressure at the pan shall be provided so the pan drains freely and unconditioned air is not drawn in through the drain.

−

−# Roof Curb and Vibration Isolation {toc}

−

−## Roof Curb {toc}

−

−```datasheet

−label: Roof Curb Type

−type: select

−options:

− - "Factory-supplied insulated curb matched to unit"

− - "Factory-supplied curb with integral vibration isolation rails"

− - "Field-fabricated curb to manufacturer's dimensions (only where unavoidable)"

−default: "Factory-supplied insulated curb matched to unit"

−```

−

−```datasheet

−label: Roof Curb Height

−type: range

−unit: in.

−drawing_ref: true

−options:

− min: 8

− max: 36

− setpoints: [8, 12, 14, 18, 24, 30, 36]

−default: 14

−```

−

−### The unit shall be set on a factory-supplied roof curb matched to the unit footprint and supply and return openings.

−

−### The curb shall be a fully welded or mechanically fastened galvanized steel assembly with integral wood nailer for roof flashing, internal cross-supports under the duct openings, and gasketing at the unit-to-curb joint.

−

−### The curb height shall provide the roofing flashing height required by the roofing system and shall be coordinated with [[sync/hvac-ductwork]] for the supply and return duct transitions.

−

−### Curb dimensions, height, and duct opening locations are [[drawing: as detailed on the roof plan and curb detail]].

−

−## Vibration Isolation {toc}

−

−```datasheet

−label: Vibration Isolation

−type: select

−options:

− - "Unit integral isolation on standard curb (typical)"

− - "Spring-isolation rail curb (noise-sensitive occupancy below)"

− - "Elastomeric-isolation rail curb"

−default: "Unit integral isolation on standard curb (typical)"

−```

−

−### Where the unit serves noise-sensitive spaces or is mounted over occupied areas with limited structural mass, vibration isolation shall be provided between the unit and the curb (isolation curb with spring or elastomeric rails) or integral to the unit base.

−

−### Rigid mounting transmits compressor and fan vibration into the roof deck and the structure below; an isolation curb breaks that path, while for units over heavy structural slabs remote from occupancy a standard curb with the unit's integral isolation is generally adequate. {note}

−

−## Seismic and Wind Restraint {toc}

−

−```datasheet

−label: Seismic / Wind Restraint

−type: radio

−options:

− - "Required — per ASCE 7 and applicable building code"

− - "Not required"

−default: "Not required"

−```

−

−### Where required by the applicable building code and ASCE 7 for the seismic design category and wind exposure, the unit and curb shall be restrained to resist the design seismic and wind forces while preserving the function of any vibration isolation.

−

−### Restraint details and anchorage are [[drawing: as detailed on the structural drawings]].

−

−# Electrical {toc}

−

−## Power Connection {toc}

−

−```datasheet

−label: Unit Disconnect

−type: radio

−options:

− - "Factory-installed non-fused disconnect switch"

− - "Factory-installed fused disconnect / HACR breaker"

− - "Field-provided disconnect within sight of unit"

−default: "Factory-installed non-fused disconnect switch"

−```

−

−### Unit electrical characteristics, including minimum circuit ampacity (MCA), maximum overcurrent protection (MOCP), voltage, and phase, shall be as published by the manufacturer for the selected configuration and shall be coordinated with the branch circuit per NFPA 70.

−

−### A factory-installed, lockable unit-mounted disconnect shall be provided.

−

−### Field power, branch circuit sizing, and overcurrent protection are [[drawing: as indicated on the electrical drawings]].

−

−## Convenience and Service Provisions {toc}

−

−```datasheet

−label: Service Receptacle

−type: radio

−options:

− - "Factory-installed unit-powered GFCI receptacle"

− - "Field-provided independent GFCI receptacle"

−default: "Factory-installed unit-powered GFCI receptacle"

−```

−

−### A unit-mounted GFCI service receptacle shall be provided where required by NFPA 70 (Article 210.63) for HVAC equipment on rooftops.

−

−### A service receptacle powered independently from the unit disconnect allows safe servicing with the unit de-energized. {note}

−

−# Controls Integration {toc}

−

−## Unit Controller and BAS Interface {toc}

−

−```datasheet

−label: BAS Communication Protocol

−type: select

−options:

− - "BACnet MS/TP (RS-485)"

− - "BACnet IP (Ethernet)"

− - "Modbus RTU (RS-485)"

− - "Modbus TCP/IP (Ethernet)"

− - "Hardwired I/O only (no network)"

−default: "BACnet MS/TP (RS-485)"

−```

−

−### The unit shall be furnished with a factory-installed, microprocessor-based unit controller that sequences cooling, heating, economizer, and ventilation, and that communicates with the project building automation system per [[sync/building-automation-system]].

−

−### The Contractor shall coordinate the communication protocol and the physical interface points with the BAS contractor before submittal.

−

−### All field control terminations shall be labeled to match the points list.

−

−## Minimum Control Points {toc}

−

−### At minimum, the unit controls interface shall make the following points available to the BAS:

−

−- Supply (discharge) air temperature

−- Return air temperature

−- Mixed air temperature (economizer-equipped units)

−- Outdoor air temperature and humidity (economizer changeover and DCV)

−- Space CO2 (DCV-equipped units)

−- Supply fan start/stop, speed command (VAV), and status

−- Compressor stage / capacity command and status by circuit

−- Heating stage / modulation command and status

−- Economizer damper position and FDD fault status

−- Outdoor-air damper position or measured outdoor airflow

−- Filter differential pressure / dirty-filter alarm

−- Refrigerant leak-detection alarm (A2L units)

−- General unit alarm and lockout status

−

−```datasheet

−label: Controls Points Package

−type: checkbox

−options:

− - "Supply (discharge) air temperature"

− - "Return air temperature"

− - "Mixed air temperature"

− - "Outdoor air temperature and humidity"

− - "Space CO2 (DCV)"

− - "Supply fan start/stop, speed, status"

− - "Compressor stage / capacity and status"

− - "Heating stage / modulation and status"

− - "Economizer position and FDD fault status"

− - "Outdoor-air damper position / measured OA airflow"

− - "Filter differential pressure / dirty-filter alarm"

− - "Refrigerant leak-detection alarm (A2L)"

− - "General alarm and lockout status"

−default: "Supply (discharge) air temperature"

−```

−

−## Smoke Detection {toc}

−

−```datasheet

−label: Duct Smoke Detector

−type: select

−options:

− - "Supply duct detector (per NFPA 90A)"

− - "Supply and return duct detectors"

− - "Return duct detector only (where required by return-air quantity)"

−default: "Supply duct detector (per NFPA 90A)"

−```

−

−### Duct smoke detection shall be provided per NFPA 90A and the IMC.

−

−### Smoke detection shall initiate unit shutdown.

−

−### Where return-air quantity exceeds the code threshold, a return-air duct smoke detector shall be provided.

−

−### Smoke detectors shall be listed for in-duct use and installed per the manufacturer's instructions for the duct cross-section.

−

−# Factory Testing {toc}

−

−```datasheet

−label: Factory Test Documentation

−type: radio

−options:

− - "Standard factory run-test report furnished"

− - "Witnessed factory test (provide 10 business days notice)"

−default: "Standard factory run-test report furnished"

−```

−

−## Every unit shall be factory run-tested before shipment, including evacuating, charging, and leak-testing the refrigerant circuit(s); each compressor and condenser fan shall be operated; the heating section shall be fired or energized and checked; and the controls shall be verified.

−

−## A factory run-test report shall be furnished as a closeout submittal.

−

−## Units that fail any test shall be corrected and retested before shipment.

−

−# Installation and Startup {toc}

−

−## Rigging and Setting {toc}

−

−```datasheet

−label: Pre-Startup Inspection Checklist

−type: checkbox

−options:

− - "Structural / curb load verified before pick"

− - "Unit level — condensate pan drains"

− - "Unit-to-curb gasket continuous and sealed"

− - "Shipping restraints removed; fan and compressor mounts free"

− - "Supply and return duct connections complete"

− - "Condensate trap installed, sized for negative pressure, and primed"

− - "Roof flashing and counterflashing complete and watertight"

− - "Electrical, disconnect, and service receptacle connected"

− - "Gas piping connected and leak-tested (gas units)"

− - "Filters installed; service clearances maintained"

−default: "Unit level — condensate pan drains"

−```

−

−### The unit shall be rigged and set on the curb per the manufacturer's instructions using the furnished lifting points and spreader bars; rigging shall not bear on cabinet panels or coils.

−

−### Before lifting, the Contractor shall verify the structural roof framing and curb are adequate for the unit operating weight, confirm the crane reach and pick plan, and verify the unit and curb supply and return openings align.

−

−### After setting, the unit shall be level so the condensate pan drains, and the unit-to-curb gasket shall be continuous and sealed.

−

−## Roofing, Flashing, and Penetrations {toc}

−

−### Roof flashing and counterflashing at the curb shall be completed by the roofing trade and shall be watertight before startup.

−

−### Duct, refrigerant (where applicable), electrical, gas, and condensate penetrations through the roof and curb shall be flashed and sealed weathertight.

−

−### The Contractor shall coordinate the flashing sequence so the curb is dried-in before the unit is set.

−

−## Duct, Gas, and Condensate Connections {toc}

−

−### Supply and return ductwork shall connect to the unit through the curb per [[sync/hvac-ductwork]], independently supported so duct weight is not carried by the cabinet.

−

−### Gas piping to gas-fired units shall include a shutoff valve, sediment trap, and union at the unit, and shall be leak-tested before firing.

−

−### The condensate drain shall include a trap sized for the unit's negative static pressure and shall be routed to an approved point of disposal with the slope and freeze protection required by the climate.

−

−## Startup and Commissioning {toc}

−

−```datasheet

−label: Commissioning Level

−type: select

−options:

− - "Manufacturer startup with TAB verification (standard)"

− - "Manufacturer startup, TAB, and functional performance testing by commissioning agent"

− - "Manufacturer startup only — no TAB (not recommended)"

−default: "Manufacturer startup with TAB verification (standard)"

−```

−

−### Initial startup shall be performed by a factory-trained representative of the manufacturer.

−

−### After startup, TAB shall be performed by an independent certified agency per [[sync/testing-adjusting-and-balancing]] to set supply, return, and outdoor airflow to design.

−

−### Startup and commissioning shall verify refrigerant charge, compressor and condenser-fan operation by stage, heating operation and turndown, economizer modulation and changeover, FDD fault reporting, minimum and demand-controlled outdoor air, safety lockouts (high-pressure, low-temperature, A2L leak detection), and correct reporting of all BAS points.

−

−# Warranty {toc}

−

−## Equipment Warranty {toc}

−

−```datasheet

−label: Equipment Warranty Period

−type: select

−options:

− - "1 year parts and labor"

− - "2 years parts and labor"

− - "1 year parts and labor, extended compressor/heat-exchanger coverage"

−default: "1 year parts and labor"

−```

−

−### The manufacturer shall warrant the unit against defects in materials and workmanship for one year from substantial completion, covering the complete assembly.

−

−### Factory-authorized service shall be available within the project region during the warranty period.

−

−## Compressor Warranty {toc}

−

−```datasheet

−label: Compressor Warranty

−type: radio

−options:

− - "1 year (same as equipment warranty)"

− - "5 years on compressor"

−default: "5 years on compressor"

−```

−

−### Each compressor shall carry an extended warranty separate from the base equipment warranty.

−

−## Heat Exchanger Warranty {toc}

−

−```datasheet

−label: Gas Heat Exchanger Warranty

−type: select

−options:

− - "Not applicable (electric / heat pump / cooling-only unit)"

− - "5 years on heat exchanger"

− - "10 years on heat exchanger"

− - "15 years / limited lifetime on heat exchanger"

−default: "10 years on heat exchanger"

−```

−

−### The gas-fired heat exchanger shall carry an extended warranty against thermal failure.

−

−## Installation Warranty {toc}

−

−### The Contractor shall warrant the installation workmanship — including curb flashing, duct and utility connections, vibration isolation, sealing, and refrigerant and condensate connections — for one year from substantial completion.

−

−# Spare Parts {toc}

−

−## Spare filters shall be stored on site in sealed packaging labeled with the unit designation and MERV rating.

−## The O&M manual shall include a maintenance schedule with recommended filter change frequency, coil cleaning, condensate system service, and A2L leak-detector check intervals.

−

−```datasheet

−label: Spare Parts at Substantial Completion

−type: checkbox

−options:

− - "One complete set of spare filters (each unit)"

− - "One set of drive belts (belt-driven supply fans)"

− - "Set of spare fuses for all fuse types installed"

− - "One spare set of access-panel gaskets"

−default: "One complete set of spare filters (each unit)"

−```

−

−# Identification and Labeling {toc}

−

−```datasheet

−label: Unit Nameplate Material

−type: radio

−options:

− - "Stainless steel — outdoor rooftop service"

− - "Anodized aluminum or laminated phenolic"

−default: "Stainless steel — outdoor rooftop service"

−```

−

−## Each unit shall bear a permanent nameplate listing the manufacturer's model and serial number, nominal cooling capacity, heating input or capacity, supply airflow, refrigerant type and total charge, electrical characteristics (voltage, phase, MCA, MOCP), and date of manufacture.

−

−## Units charged with an A2L refrigerant shall bear the flammable-refrigerant marking required by UL 60335-2-40 and ASHRAE 15.

−

−## Access panels shall be labeled to identify the section behind each panel.

+---

+title: Packaged Rooftop Units

+category: Mechanical / Air Distribution

+description: >

+ When to use: Factory-assembled, self-contained packaged units with an integral direct-expansion refrigeration circuit, set on a roof curb and serving a field-installed duct distribution system. Covers cooling-only, gas-fired, electric resistance, hydronic, and reverse-cycle heat pump heating configurations; constant-volume, multi-speed, and variable-air-volume supply fans; air-side economizers, powered relief, minimum outdoor air control, demand-controlled ventilation, and integral exhaust air energy recovery; the cabinet, filtration, drain pan, and roof curb; the refrigerant, its safety group, and the detection and mitigation provisions that go with mildly flammable refrigerants; unit-mounted controls and their interface to the building automation system; and the setting, connection, startup, and balancing of the installed unit.

+ Not intended for: Central station air handling units served by a chilled water or heating water plant ([[sync/air-handling-units]]); split-system equipment with a remote condensing section ([[sync/split-system-air-conditioners]]) and the field refrigerant piping between them ([[sync/refrigerant-piping]]); through-the-wall packaged terminal units ([[sync/packaged-terminal-air-conditioners]]); dedicated outdoor air units ([[sync/dedicated-outdoor-air-systems]]); variable refrigerant flow systems ([[sync/variable-refrigerant-flow-systems]]); stand-alone energy recovery ventilators ([[sync/energy-recovery-ventilators]]); ductwork and duct accessories beyond the unit connection ([[sync/hvac-ductwork]]); air terminal units downstream of the unit ([[sync/air-terminal-units]]); the building automation system and its sequences ([[sync/building-automation-system]]); and testing, adjusting, and balancing of the completed air distribution system ([[sync/testing-adjusting-and-balancing]]).

+---

+# Scope {toc}

+## A packaged rooftop unit is a single factory-assembled cabinet that contains the compressors, the air-cooled condenser, the evaporator coil, the supply fan, the heating section, the outdoor air and economizer dampers, the filters, and the unit controls, charged with refrigerant and run-tested before it leaves the factory. What separates it from a central station air handling unit is that the refrigeration plant is inside the box, so the building furnishes a curb, a duct connection, power, and where applicable gas and condensate drainage, and nothing else. {note}

+## The following are covered when they form part of the unit: {note}

+- Cabinet, base, access panels, and exterior finish

+- Compressors, refrigerant circuits, condenser coil and fans, evaporator coil, and expansion devices

+- Refrigerant detection and mitigation provisions

+- Supply fan, motor, and drive, and any powered relief or exhaust fan

+- Gas-fired, electric resistance, hydronic, and reverse-cycle heat pump heating sections

+- Outdoor air, return air, and relief dampers, the air-side economizer, and minimum outdoor air control

+- Integral exhaust air energy recovery sections

+- Filter section, drain pan, and condensate trap

+- Roof curb, vibration isolation, and seismic and wind restraint at the curb

+- Unit-mounted controls, safety devices, and the physical interface to the building automation system

+- Rigging, setting, connection, startup, and commissioning of the installed unit

+## The following are outside this standard: {note}

+- Ductwork, duct accessories, and duct insulation beyond the unit connection, covered by [[sync/hvac-ductwork]] and [[sync/duct-accessories]]

+- Air terminal units and the zone controls served by a variable-air-volume unit, covered by [[sync/air-terminal-units]]

+- Central station air handling units and their hydronic plant, covered by [[sync/air-handling-units]] and [[sync/chillers]]

+- Split-system equipment and the field refrigerant piping it depends on, covered by [[sync/split-system-air-conditioners]] and [[sync/refrigerant-piping]]

+- Stand-alone energy recovery ventilators and dedicated outdoor air units, covered by [[sync/energy-recovery-ventilators]] and [[sync/dedicated-outdoor-air-systems]]

+- Variable frequency drives furnished as separate components, covered by [[sync/hvac-variable-frequency-drives]]

+- Gas piping to the unit connection, covered by [[sync/natural-gas-piping]] and [[sync/fuel-gas-piping]]

+- Condensate drain piping beyond the unit trap, covered by [[sync/condensate-drainage-piping]]

+- The roofing membrane and the flashing of the curb into it, covered by [[sync/membrane-roofing]] and [[sync/sheet-metal-flashing-and-trim]]

+- The building automation system, its sequences of operation, and control devices not mounted on the unit, covered by [[sync/building-automation-system]] and [[sync/hvac-controls-instrumentation]]

+- The fire alarm system that receives the duct smoke detector signal, covered by [[sync/fire-alarm-systems]]

+- Testing, adjusting, and balancing of the completed system, covered by [[sync/testing-adjusting-and-balancing]]

+## Each unit shall be furnished as a complete assembly by a single manufacturer, who shall be responsible for the refrigeration, air-side, heating, and control performance of the unit as a whole.

+## The unit locations and tags shall be as indicated on [[drawing: the mechanical roof plan]].

+## Per-tag quantities are scheduled and project-wide policy is selected in the datasheet. Capacities, airflows, static pressures, heating inputs, and electrical characteristics vary with every unit on the roof and live on the mechanical equipment schedule; the construction, options, control, and warranty decisions that apply to every unit on the project are made once here. {note}

+## Where a requirement of this standard conflicts with a requirement of a standard that governs a connected system, the Engineer of Record shall make the initial determination of which requirement governs.

+# Referenced Standards {toc}

+## Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.

+## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

+| Standard | Title |

+|----------|-------|

+| ANSI/AHRI 340/360 (I-P) | Performance Rating of Commercial and Industrial Unitary Air-conditioning and Heat Pump Equipment |

+| ANSI/AHRI 210/240 | Performance Rating of Unitary Air-conditioning and Air-source Heat Pump Equipment |

+| ANSI/AHRI 270 | Sound Performance Rating of Outdoor Unitary Equipment |

+| ANSI/AHRI 370 | Sound Performance Rating of Large Air-cooled Outdoor Refrigerating and Air-conditioning Equipment |

+| ANSI/AHRI 1060 | Performance Rating of Air-to-Air Exchangers for Energy Recovery Ventilation Equipment |

+| ANSI/ASHRAE/IES 90.1 | Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings |

+| ANSI/ASHRAE 62.1 | Ventilation and Acceptable Indoor Air Quality |

+| ANSI/ASHRAE 15 | Safety Standard for Refrigeration Systems |

+| ANSI/ASHRAE 34 | Designation and Safety Classification of Refrigerants |

+| ANSI/ASHRAE 52.2 | Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size |

+| ANSI/ASHRAE 84 | Method of Testing Air-to-Air Heat/Energy Exchangers |

+| ANSI/AMCA 210 / ANSI/ASHRAE 51 | Laboratory Methods of Testing Fans for Certified Aerodynamic Performance Rating |

+| ANSI/AMCA 500-D | Laboratory Methods of Testing Dampers for Rating |

+| ANSI/AMCA 610 | Laboratory Methods of Testing Airflow Measurement Stations for Performance Rating |

+| UL 60335-2-40 | Household and Similar Electrical Appliances - Safety - Particular Requirements for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers |

+| UL 1995 | Heating and Cooling Equipment |

+| UL 900 | Air Filter Units |

+| UL 508A | Industrial Control Panels |

+| ANSI Z21.47 / CSA 2.3 | Gas-Fired Central Furnaces |

+| NFPA 54 / ANSI Z223.1 | National Fuel Gas Code |

+| NFPA 70 | National Electrical Code |

+| NFPA 72 | National Fire Alarm and Signaling Code |

+| NFPA 90A | Standard for the Installation of Air-Conditioning and Ventilating Systems |

+| NEMA MG 1 | Motors and Generators |

+| ASTM A653 | Steel Sheet, Zinc-Coated or Zinc-Iron Alloy-Coated by the Hot-Dip Process |

+| ASTM B117 | Operating Salt Spray (Fog) Apparatus |

+| ASCE 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures |

+| IMC | International Mechanical Code |

+| IFGC | International Fuel Gas Code |

+| IECC | International Energy Conservation Code |

+| SMACNA HVAC Duct Construction Standards | HVAC Duct Construction Standards - Metal and Flexible |

+| 10 CFR Part 431 | Energy Efficiency Program for Certain Commercial and Industrial Equipment |

+| 40 CFR Part 82 Subpart F | Recycling and Emissions Reduction |

+| 40 CFR Part 84 | Phasedown of Hydrofluorocarbons, Technology Transition |

+# Submittals {toc}

+## Action Submittals {toc}

+### The Contractor shall submit the following for each unit tag:

+- Unit configuration drawing showing overall dimensions, duct connection sizes and locations, operating and shipping weights, center of gravity, corner weights, and the service clearances on every side

+- Certified cooling performance at the scheduled entering conditions, giving net total and net sensible capacity after deduction of supply fan heat, the certification program the rating is published under, and the full-load and part-load efficiency ratings

+- Heating performance for the selected heating source, giving input and output for gas-fired sections with the certification identified, capacity and stage count for electric sections, integrated heating capacity at the outdoor design temperature and at the compressor heating operation limit for heat pumps, and coil selection data for hydronic sections

+- Refrigerant designation, safety group, and factory charge by circuit, and where a refrigerant detection system is furnished, the sensor locations, the mitigation action, and the charge limit the listing establishes for the unit

+- Compressor data giving type, quantity, capacity control method, and the minimum capacity step

+- Supply fan selection data showing the certified fan curve with the design operating point plotted against the calculated system resistance, the shaft power at that point, and the fan system power compliance calculation

+- Motor data giving nameplate power, speed, voltage, phase, full-load amperes, efficiency, enclosure, and inverter-duty rating where applicable

+- Economizer assembly data giving damper leakage class, actuator type and fail position, high-limit control type, relief arrangement, and fault detection and diagnostics provisions

+- Minimum outdoor air control data giving the control method, the measurement device rating where a station is furnished, and the demand-controlled ventilation sensing provisions

+- Energy recovery data giving the device type, effectiveness at design conditions, added pressure drop on each airstream, exhaust air transfer ratio, and frost control method, where a recovery section is furnished

+- Sound power levels for the outdoor radiated path under the applicable sound rating program, and for the supply discharge and return inlet paths in octave bands

+- Cabinet construction details giving panel construction, insulation type and thermal resistance, exterior finish and its salt spray rating, and access panel arrangement

+- Filter data giving efficiency rating, depth, quantity and size per unit, initial resistance, and recommended change-out resistance

+- Drain pan drawing giving material, slope, extent, connection size and location, and the trap arrangement

+- Roof curb drawing giving curb height, plan dimensions, insulation, wood nailer, duct opening locations, cross supports, gasketing, and the unit-to-curb attachment

+- Vibration isolation data and, where restraint is required, seismic and wind restraint details and calculations bearing the seal of an engineer licensed in the jurisdiction of the project

+- Electrical data giving minimum circuit ampacity, maximum overcurrent protective device, short-circuit current rating of the control panel, disconnect configuration, and the wiring diagram with field termination points

+- Unit controller data giving the control configuration, the communication interface, and a complete point list with object names, types, units, and read or write access

+```datasheet

+label: Action Submittals Required

+type: checkbox

+options:

+ - "Unit configuration drawing with weights and service clearances"

+ - "Certified cooling performance and efficiency ratings"

+ - "Heating performance for the selected heating source"

+ - "Refrigerant, charge, and detection system data"

+ - "Compressor and capacity control data"

+ - "Certified fan curve and fan power compliance"

+ - "Motor data"

+ - "Economizer assembly data"

+ - "Minimum outdoor air and demand-controlled ventilation data"

+ - "Energy recovery data"

+ - "Sound power levels"

+ - "Cabinet construction details"

+ - "Filter data"

+ - "Drain pan and trap drawing"

+ - "Roof curb drawing"

+ - "Vibration isolation and restraint data"

+ - "Electrical data and wiring diagram"

+ - "Unit controller data and point list"

+default:

+ - "Unit configuration drawing with weights and service clearances"

+ - "Certified cooling performance and efficiency ratings"

+ - "Heating performance for the selected heating source"

+ - "Refrigerant, charge, and detection system data"

+ - "Compressor and capacity control data"

+ - "Certified fan curve and fan power compliance"

+ - "Motor data"

+ - "Economizer assembly data"

+ - "Minimum outdoor air and demand-controlled ventilation data"

+ - "Sound power levels"

+ - "Cabinet construction details"

+ - "Filter data"

+ - "Drain pan and trap drawing"

+ - "Roof curb drawing"

+ - "Vibration isolation and restraint data"

+ - "Electrical data and wiring diagram"

+ - "Unit controller data and point list"

+```

+### No unit shall be released for fabrication until the action submittal for that unit has been reviewed and returned.

+### The configuration drawing shall show the condenser coil clearance, the filter withdrawal clearance, the compressor compartment access, and the heat exchanger or electric heater withdrawal path, dimensioned from the unit face.

+### The corner weights and center of gravity on the configuration drawing are what the structural engineer checks the roof framing against, and a unit whose weight moved when an option was added is discovered as a deflected deck rather than a submittal comment unless the drawing carries the as-configured values. {note}

+## Informational Submittals {toc}

+### The Contractor shall submit the following for information at the times indicated in each item:

+- Rigging and setting plan, submitted before the unit ships, showing the crane location, the pick radius, the lifting points and spreader arrangement, and the temporary loads imposed on the roof structure

+- Refrigerant handling certification under 40 CFR Part 82 Subpart F for every individual who will open, evacuate, charge, or recover a refrigerant circuit on the project

+- Evidence of training in mildly flammable refrigerant handling for every individual who will work on a unit carrying a refrigerant in a flammable safety group

+- Manufacturer's field service report for each site visit made during the warranty period

+- Written record of the pre-existing condition of any roofing or adjacent surface the Contractor is required to restore

+```datasheet

+label: Informational Submittals Required

+type: checkbox

+options:

+ - "Rigging and setting plan before shipment"

+ - "Refrigerant handling certifications"

+ - "Flammable refrigerant training records"

+ - "Field service reports during the warranty period"

+ - "Pre-existing condition record for restored surfaces"

+default:

+ - "Rigging and setting plan before shipment"

+ - "Refrigerant handling certifications"

+ - "Field service reports during the warranty period"

+```

+## Closeout Submittals {toc}

+### The Contractor shall submit the following at or before substantial completion:

+- Operation and maintenance manuals for each unit, indexed by unit tag, containing installation, operation, maintenance, and troubleshooting instructions, a parts list for every furnished component, and the maintenance schedule for filters, coils, condensate system, belts, and refrigerant detection sensors

+- As-built wiring diagrams and the building automation system point list with the terminal designations used on the unit

+- Certified factory run-test report for each unit

+- Startup report for each unit signed by the person who performed the startup, recording refrigerant charge by circuit, operating pressures and temperatures, motor current, and the setpoint of every safety device

+- Refrigerant charge record for each unit giving the refrigerant designation, the factory charge by circuit, and any field adjustment with the weight added or removed

+- Commissioning record demonstrating economizer changeover, fault detection reporting, minimum and demand-controlled outdoor air, safety lockouts, and refrigerant detection and mitigation where furnished

+- Air balance report for the units and their connected systems

+- Record of the filter media installed at substantial completion, giving efficiency rating, quantity, size, and installation date

+- Warranty documentation correlating each unit serial number to its installation date and to the expiration date of the unit, compressor, and heat exchanger warranties

+- Signed receipt from the Owner for the spare parts delivered

+```datasheet

+label: Closeout Submittals Required

+type: checkbox

+options:

+ - "Operation and maintenance manuals indexed by unit tag"

+ - "As-built wiring diagrams and point list"

+ - "Certified factory run-test report for each unit"

+ - "Signed startup report for each unit"

+ - "Refrigerant charge record for each unit"

+ - "Commissioning record"

+ - "Air balance report"

+ - "Installed filter media record"

+ - "Warranty documentation correlated to serial numbers"

+ - "Spare parts receipt"

+default:

+ - "Operation and maintenance manuals indexed by unit tag"

+ - "As-built wiring diagrams and point list"

+ - "Certified factory run-test report for each unit"

+ - "Signed startup report for each unit"

+ - "Refrigerant charge record for each unit"

+ - "Commissioning record"

+ - "Air balance report"

+ - "Installed filter media record"

+ - "Warranty documentation correlated to serial numbers"

+ - "Spare parts receipt"

+```

+# Quality Assurance {toc}

+## Manufacturer Qualifications {toc}

+### The unit manufacturer shall have produced packaged unitary equipment of the type furnished for not less than the number of years indicated in the datasheet.

+```datasheet

+label: Minimum Manufacturer Experience

+type: range

+unit: years

+options:

+ min: 0

+ max: 25

+ step: 1

+default: 5

+```

+### The manufacturer shall make replacement parts available for the units furnished for not less than ten years after the date of manufacture.

+### An experience requirement is a proxy for production maturity, not a measure of it, and it excludes new entrants along with unproven ones. A project prepared to accept a well-capitalized new manufacturer can set the requirement to zero and rely on the certification, testing, and warranty requirements instead. {note}

+## Performance Certification {toc}

+### Published cooling and heating capacities and efficiency ratings shall be certified under the program indicated in the datasheet.

+```datasheet

+label: Performance Certification Program

+type: radio

+derived: "the unit's cooling capacity, with 65,000 Btu/h and above rated under AHRI 340/360 and below 65,000 Btu/h under AHRI 210/240"

+options:

+ - "AHRI 340/360"

+ - "AHRI 210/240"

+default: derived

+```

+### The published data submitted shall bear the certification mark of the program under which the ratings are certified.

+### Capacities and efficiencies stated in the submittal shall be the certified ratings and not uncertified catalog selections.

+### Where a selected configuration falls outside the scope of the certification program, the manufacturer shall state that fact in the submittal and shall furnish the test data on which the rating is based.

+### The two programs split at 65,000 Btu/h because the federal minimum efficiency rules split there. Below the line the equipment is rated by the residential-style seasonal metrics, above it by the commercial full-load and integrated part-load metrics, and the same physical unit can carry a different efficiency number depending on which side of the line it is rated on. {note}

+## Safety Listing {toc}

+### The complete unit, including every factory-installed electrical and refrigerant-system component, shall be listed and labeled by a Nationally Recognized Testing Laboratory under the standard indicated in the datasheet.

+```datasheet

+label: Unit Safety Listing Standard

+type: radio

+options:

+ - "UL 60335-2-40"

+ - "UL 1995"

+```

+### A unit charged with a refrigerant in a flammable safety group shall be listed under UL 60335-2-40.

+### Units listed to UL 1995 are acceptable only where the refrigerant is in a nonflammable safety group and the Authority Having Jurisdiction accepts that listing for the equipment furnished.

+### Gas-fired heating sections shall additionally be certified to ANSI Z21.47 / CSA 2.3.

+### Factory-wired control panels shall be listed to UL 508A.

+### Each factory-wired control panel shall bear a label giving the short-circuit current rating of the panel.

+### UL 60335-2-40 is the listing standard that contains the charge limits, the refrigerant detection requirements, and the mitigation logic for mildly flammable refrigerants, which is why a flammable-refrigerant unit cannot be listed under the older standard. For a nonflammable refrigerant, both listings cover the same hazards and the choice follows the manufacturer's certification history and what the Authority Having Jurisdiction has seen before. {note}

+## Refrigerant Handling Qualification {toc}

+### Refrigerant circuits shall be opened, evacuated, charged, and recovered only by an individual certified under 40 CFR Part 82 Subpart F.

+### Where the unit carries a refrigerant in a flammable safety group under ASHRAE 34, the individuals working on the circuit shall have completed training covering the handling, storage, leak response, and tool requirements that apply to that refrigerant.

+### Recovery machines, vacuum pumps, manifolds, leak detectors, and charging equipment used on a unit carrying a refrigerant in a flammable safety group shall be rated by their makers for that service.

+## Preinstallation Conference {toc}

+### A preinstallation conference shall be held before the first curb is set, attended by the Contractor, the mechanical installer, the roofing installer, the electrical installer, the controls installer, the testing and balancing agent, the commissioning agent where one is engaged, and the Owner's representative.

+### The conference agenda shall cover the curb setting and flashing sequence, the structural readiness at each unit location, the crane plan, the utility connections and their sequence, the refrigerant safety provisions, the controls interface and point responsibility, and the startup and commissioning schedule.

+# Service Conditions and Site Data {toc}

+## Outdoor Design Conditions {toc}

+### Each unit shall deliver its scheduled net cooling capacity at [[parameter: site-ambient-temperature-maximum]] with the condenser coil clean.

+### The integrated heating capacity of each heat pump unit at [[parameter: site-ambient-temperature-minimum]] shall be stated in the submittal.

+### Cooling, heating, fan, and motor ratings shall be corrected for [[parameter: altitude]] in accordance with the manufacturer's published correction factors.

+### The altitude-corrected ratings shall be the values published in the submittal.

+### Gas-fired heating sections shall be de-rated for [[parameter: altitude]] in accordance with the listing and NFPA 54.

+### The altitude de-rated gas input shall be stated in the submittal.

+### Air-cooled condensing capacity falls as the outdoor temperature rises, so a unit rated at a standard test condition delivers less than its nominal tonnage on the design day, and less again in a rooftop microclimate where the condenser draws air heated by the roof surface and by neighboring units. The scheduled capacity is a net value at the site condition, not a nominal tonnage. {note}

+### Thinner air at elevation reduces both the mass of air the fan moves and the heat the condenser rejects, and it reduces the mass of gas a burner orifice passes, so every rating on the unit carries its own altitude correction and a sea-level selection installed at elevation is short on every one of them at once. {note}

+## Low-Ambient Cooling Operation {toc}

+### Mechanical cooling shall be available down to the outdoor temperature indicated in the datasheet.

+```datasheet

+label: Minimum Outdoor Temperature for Mechanical Cooling Operation

+type: range

+unit: °F

+options:

+ min: -20

+ max: 65

+ setpoints: [-20, -10, 0, 10, 20, 30, 40, 50, 55, 65]

+```

+### The low-ambient cooling provision furnished shall be as indicated in the datasheet.

+```datasheet

+label: Low-Ambient Cooling Provision

+type: select

+derived: "the minimum outdoor temperature for mechanical cooling operation selected in the datasheet, compared against the manufacturer's published low-ambient limit for the unit without added provisions"

+options:

+ - "None"

+ - "Condenser fan cycling"

+ - "Condenser fan speed control"

+ - "Low-ambient head pressure control kit"

+default: derived

+```

+### Where the datasheet does not state a minimum outdoor temperature for mechanical cooling, the unit shall be furnished for mechanical cooling down to the manufacturer's published low-ambient limit without added provisions, and that limit shall be stated in the submittal.

+### Below roughly 55°F an economizer can carry the cooling load of most spaces, so the compressors on an economizer-equipped unit rarely need to run in cold weather. A space with a year-round internal load, a unit with no economizer, or a unit that serves a process does need them, and a compressor run at low outdoor temperature without head pressure control floods, loses oil, and trips on low pressure. The provision follows from the temperature the project needs cooling at, which is a load question rather than a preference. {note}

+## Corrosive Atmospheres {toc}

+### The condenser coil corrosion protection shall be as indicated in the datasheet.

+```datasheet

+label: Condenser Coil Corrosion Protection

+type: select

+options:

+ - "Uncoated aluminum fin on copper tube"

+ - "Aluminum fin on copper tube with an electrodeposited epoxy coating"

+ - "Aluminum fin on copper tube with an applied phenolic coating"

+ - "Microchannel aluminum coil with an electrodeposited coating"

+ - "Copper fin on copper tube"

+default: "Uncoated aluminum fin on copper tube"

+```

+### The evaporator coil corrosion protection shall be as indicated in the datasheet.

+```datasheet

+label: Evaporator Coil Corrosion Protection

+type: select

+options:

+ - "Uncoated aluminum fin on copper tube"

+ - "Aluminum fin on copper tube with an electrodeposited epoxy coating"

+ - "Aluminum fin on copper tube with an applied phenolic coating"

+ - "Copper fin on copper tube"

+default: "Uncoated aluminum fin on copper tube"

+```

+### Where a coil coating is selected, the coating shall be applied after fin and tube assembly so that the tube-to-fin interface is coated.

+### Where a coil coating is selected, the manufacturer shall state in the submittal the salt spray exposure the coated coil has been tested to.

+### Aluminum fin on copper tube is a galvanic pair that stays benign while the fin surface is dry and becomes active once a persistent electrolyte film forms between them. Chloride from marine air and sulfur compounds from industrial and vehicular exhaust both supply that electrolyte, so the fin corrodes preferentially, the bond to the tube opens, and heat rejection falls while compressor discharge pressure rises. The condenser coil sees the outdoor atmosphere continuously and the evaporator coil sees it only through the outdoor air fraction, which is why the two are selected separately. {note}

+### An electrodeposited coating is applied by immersing the finished coil and curing a uniform film onto every surface, so it protects the fin-to-tube joint where a sprayed coating cannot reach; it also adds a small thermal resistance, and the coated coil's capacity is what the submittal reports. {note}

+# Cooling Performance and Efficiency {toc}

+## Cooling Capacity {toc}

+### The nominal cooling capacity of each unit shall be as indicated in the datasheet.

+```datasheet

+label: Nominal Cooling Capacity

+type: range

+unit: tons

+drawing_ref: "the mechanical equipment schedule"

+options:

+ min: 2

+ max: 150

+ setpoints: [2, 2.5, 3, 4, 5, 6, 7.5, 8.5, 10, 12.5, 15, 17.5, 20, 25, 30, 35, 40, 50, 60, 70, 75, 80, 90, 100, 110, 120, 130, 150]

+default: deferred

+```

+### The net total and net sensible cooling capacity of each unit at the scheduled entering air conditions shall be not less than the values indicated on [[drawing: the mechanical equipment schedule]].

+### Net capacity shall be stated after deduction of supply fan motor heat at the design fan operating point.

+### The unit shall be selected so that both the total and the sensible capacity are met.

+### A selection that meets the total capacity with a sensible heat ratio higher than the space load requires shall be reported to the Engineer of Record before the unit is released.

+### A unit selected on total capacity alone can meet the scheduled tonnage and still fail to hold humidity, because it delivers the total as too much sensible cooling and too little latent. The space then reaches its dry-bulb setpoint and the compressor cycles off before the coil has removed the moisture, which is the mechanism behind a cold, damp building served by a unit that is nominally large enough. {note}

+## Efficiency Ratings for Units of 65,000 Btu/h and Above {toc}

+### Requirements in this article apply to units rated under AHRI 340/360.

+### The full-load energy efficiency ratio shall be not less than the value indicated in the datasheet.

+```datasheet

+label: Minimum Full-Load Energy Efficiency Ratio (EER)

+type: range

+unit: EER

+derived: "the minimum [[parameter: adopted-energy-code]] and 10 CFR Part 431 require for the unit's cooling capacity class and heating source"

+options:

+ min: 8

+ max: 16

+ step: 0.1

+default: derived

+```

+### The integrated energy efficiency ratio shall be not less than the value indicated in the datasheet.

+```datasheet

+label: Minimum Integrated Energy Efficiency Ratio (IEER)

+type: range

+unit: IEER

+derived: "the minimum [[parameter: adopted-energy-code]] and 10 CFR Part 431 require for the unit's cooling capacity class and heating source"

+options:

+ min: 10

+ max: 25

+ step: 0.1

+default: derived

+```

+### Heat pump units rated under AHRI 340/360 shall have a heating coefficient of performance at 47°F outdoor not less than the value indicated in the datasheet.

+```datasheet

+label: Minimum Heat Pump Heating Coefficient of Performance at 47°F

+type: range

+unit: COP

+derived: "the minimum [[parameter: adopted-energy-code]] and 10 CFR Part 431 require for the unit's heating capacity class"

+options:

+ min: 2.5

+ max: 5

+ step: 0.1

+default: derived

+```

+### The code minimum is a floor rather than a target. A project that wants a higher efficiency for life-cycle reasons enters the higher value in place of the derived one, and the derived state exists so that a project that wants only compliance does not have to look the table up. {note}

+### The integrated ratio weights performance at four load points, three of them part load, so it is the metric that tracks the operating cost of a unit that spends most of its hours below full capacity; the full-load ratio describes the design-day condition and the peak electrical demand. Two units with the same full-load rating can differ substantially in the integrated rating depending on how they unload. {note}

+## Efficiency Ratings for Units Below 65,000 Btu/h {toc}

+### Requirements in this article apply to units rated under AHRI 210/240.

+### The seasonal energy efficiency ratio shall be not less than the value indicated in the datasheet.

+```datasheet

+label: Minimum Seasonal Energy Efficiency Ratio (SEER2)

+type: range

+unit: SEER2

+derived: "the minimum [[parameter: adopted-energy-code]] and the federal appliance efficiency rules require for the unit's capacity and configuration"

+options:

+ min: 12

+ max: 24

+ step: 0.1

+default: derived

+```

+### Heat pump units rated under AHRI 210/240 shall have a heating seasonal performance factor not less than the value indicated in the datasheet.

+```datasheet

+label: Minimum Heating Seasonal Performance Factor (HSPF2)

+type: range

+unit: HSPF2

+derived: "the minimum [[parameter: adopted-energy-code]] and the federal appliance efficiency rules require for the unit's capacity and configuration"

+options:

+ min: 6

+ max: 13

+ step: 0.1

+default: derived

+```

+### The seasonal metrics are rated under a revised test procedure whose external static pressure is closer to a real duct system than the earlier procedure, which is why the numbers carry the suffix and are not interchangeable with the earlier ratings of the same name. {note}

+## Fan System Power {toc}

+### The fan system power of each unit at the design airflow and design external static pressure shall not exceed the limit [[parameter: adopted-energy-code]] sets for that airflow, with every pressure drop credit claimed identified in the submittal.

+### Fan system power shall be computed from the fan shaft power and the motor and drive efficiencies at the design operating point rather than from the motor nameplate.

+### The fan power limit is a statement about the whole air system rather than the fan. A unit that carries a high-efficiency fan can still exceed the limit if the ductwork, filters, and energy recovery section it pushes through add up to more resistance than the allowance, which is why the credits for filters and recovery devices exist and why they have to be documented. {note}

+# Refrigerant System {toc}

+## Refrigerant and Safety Group {toc}

+### The refrigerant shall be as indicated in the datasheet.

+```datasheet

+label: Refrigerant Designation (ASHRAE 34)

+type: select

+options:

+ - "R-454B"

+ - "R-32"

+ - "R-410A"

+default: manufacturer

+```

+### Where the datasheet leaves the refrigerant to the manufacturer, the manufacturer shall state in the submittal the refrigerant the unit is charged with and its safety group.

+### The refrigerant shall be one that 40 CFR Part 84 permits in equipment of the unit's class on the unit's date of manufacture.

+### Where a unit is furnished as a replacement that retains existing refrigerant piping, coils, or components, the refrigerant selected in the datasheet shall be compatible with the retained components.

+### Where a retained refrigerant circuit is connected to a new unit, the Contractor shall confirm the refrigerant present in the retained circuit before any new component is connected to it.

+### The refrigerant safety group shall be as indicated in the datasheet.

+```datasheet

+label: Refrigerant Safety Group (ASHRAE 34)

+type: select

+derived: "the safety classification ASHRAE 34 publishes for the refrigerant the unit is charged with"

+options:

+ - "A1"

+ - "A2L"

+default: derived

+```

+### Under the technology transition rule at 40 CFR Part 84, packaged unitary equipment manufactured after the compliance date for its class is limited to refrigerants below a stated global warming potential, and the refrigerants that meet that limit at the pressures this equipment runs at are classified A2L. The refrigerant is therefore a property of the product line rather than a specification choice for new equipment, and the datasheet asserts one only where a project has a reason to, such as matching a retained circuit. {note}

+### The safety group is the switch that turns the detection, mitigation, marking, and training articles of this standard on or off, and it follows from the refrigerant rather than from any project decision. {note}

+## Refrigerant Detection and Mitigation {toc}

+### The refrigerant detection provision shall be as indicated in the datasheet.

+```datasheet

+label: Refrigerant Detection System

+type: radio

+derived: "the refrigerant safety group and the charge per circuit, compared against the releasable charge limit UL 60335-2-40 establishes for the unit and the smallest space it serves"

+options:

+ - "Factory-installed refrigerant detection system with mitigation"

+ - "No refrigerant detection system"

+default: derived

+```

+### Where a refrigerant detection system is furnished, the sensors, their locations, and the mitigation sequence shall be as covered by the unit listing.

+### The Contractor shall not relocate a refrigerant detection sensor or alter the mitigation sequence in the field.

+### On detection, the mitigation sequence shall start the supply fan to dilute the released refrigerant, shall de-energize the ignition sources the listing identifies, and shall continue until the measured concentration has fallen below the reset threshold.

+### Where a refrigerant detection system is furnished, its alarm shall be exposed to the building automation system as a discrete point regardless of the control points selected in the datasheet.

+### Detection sensors shall be installed with the date of installation recorded on the device.

+### The end of the published service life of each detection sensor shall be recorded in the closeout documents.

+### A refrigerant in the A2L group burns, but only within a narrow concentration band and only with a strong ignition source, so the listing manages the hazard by keeping the concentration in any space below a fraction of the lower flammability limit. The detection system is how a unit whose charge exceeds the amount that could be released safely into the smallest connected space stays within that fraction: it dilutes the leak through the duct system before the concentration can build. Whether a given unit needs it is a calculation on the charge and the space, which is why it is derived rather than chosen. {note}

+### The mitigation depends on the supply fan running and on the duct system being connected, so a unit that is powered before its ductwork is complete, or whose fan is disabled for service, is outside the condition the listing assumed; the flammable refrigerant training and the shutdown procedure exist for that window. {note}

+## Compressors {toc}

+### The compressor type shall be as indicated in the datasheet.

+```datasheet

+label: Compressor Type

+type: select

+options:

+ - "Hermetic scroll"

+ - "Semi-hermetic reciprocating"

+ - "Semi-hermetic screw"

+default: "Hermetic scroll"

+```

+### The cooling capacity control shall be as indicated in the datasheet.

+```datasheet

+label: Cooling Capacity Control

+type: select

+options:

+ - "Single stage"

+ - "Two stages"

+ - "Three or more stages"

+ - "Variable capacity by digital scroll unloading"

+ - "Variable capacity by inverter-driven compressor"

+```

+### The number of cooling capacity steps or the modulation range shall be not less than [[parameter: adopted-energy-code]] requires for the unit's cooling capacity and supply fan control.

+### The smallest cooling capacity step shall be not more than the percentage of full capacity indicated in the datasheet.

+```datasheet

+label: Largest Permitted Minimum Cooling Capacity Step

+type: range

+unit: '%'

+options:

+ min: 10

+ max: 100

+ setpoints: [10, 15, 20, 25, 33, 50, 100]

+```

+### Where the datasheet does not state a minimum capacity step, the manufacturer shall state the minimum step of the furnished unit in the submittal.

+### No capacity control method is the norm across projects, because the answer depends on how the unit is used. A single-zone constant-volume unit serving a space with a steady load cycles a single compressor acceptably; a variable-air-volume unit or a unit serving a space whose load swings needs capacity that follows the load, and the choice between staged compressors and a modulating one turns on the part-load efficiency the project is paying for against the first cost and the service familiarity of the maintaining staff. {note}

+### Each compressor shall be mounted on vibration isolators within the cabinet.

+### The compressor suction and discharge connections shall be arranged so that compressor vibration is not transmitted into the coil tubing.

+### The compressor provisions furnished shall be as indicated in the datasheet.

+```datasheet

+label: Compressor Provisions

+type: checkbox

+options:

+ - "Crankcase heater on each compressor"

+ - "Acoustic blanket on each compressor"

+ - "Suction and discharge service valves on each compressor"

+ - "Compressor current sensing reported to the unit controller"

+default:

+ - "Crankcase heater on each compressor"

+```

+## Refrigerant Circuits {toc}

+### The minimum number of independent refrigerant circuits per unit shall be as indicated in the datasheet.

+```datasheet

+label: Minimum Number of Independent Refrigerant Circuits

+type: range

+unit: circuits

+options:

+ min: 1

+ max: 4

+ setpoints: [1, 2, 3, 4]

+```

+### Each independent circuit shall have its own compressor or compressors, expansion device, evaporator coil section, and condenser coil section, so that a failure in one circuit does not disable the others.

+### Where the minimum circuit count indicated in the datasheet is not offered by the manufacturer at a tag's nominal capacity, the Contractor shall report the conflict to the Engineer of Record before the unit is released for fabrication.

+### Units of small nominal capacity are built with a single circuit, and multiple circuits become available as the capacity rises, so a project-wide circuit minimum is a statement about the larger units on the roof. Two circuits buy partial cooling through a compressor failure and a natural first stage of capacity control; they cost a second expansion device, a second set of controls, and a split coil whose active face shrinks when one circuit is off. {note}

+### The expansion device on each circuit shall be as indicated in the datasheet.

+```datasheet

+label: Expansion Device

+type: select

+options:

+ - "Thermostatic expansion valve"

+ - "Electronic expansion valve"

+ - "Fixed orifice"

+```

+### Each circuit shall be furnished with a high-pressure cutout, a low-pressure cutout or loss-of-charge protection, and a compressor motor overload, each of which shall stop the compressor independently of the unit controller.

+### Each circuit shall be furnished with a liquid line filter-drier and with service access ports on the high and low sides.

+### Where the datasheet selects variable capacity, the expansion device shall be one that maintains superheat control across the full modulation range of the compressor.

+### A thermostatic valve controls superheat mechanically and holds a stable feed across the capacity range of a staged compressor. A modulating compressor runs at mass flows a mechanical valve was not sized for at both ends of its range, which is the condition an electronic valve exists for, and it is also the device that lets the controller manage superheat during the low-load and low-ambient operation a modulating unit is bought to run in. {note}

+## Dehumidification Reheat {toc}

+### The dehumidification reheat provision shall be as indicated in the datasheet.

+```datasheet

+label: Dehumidification Reheat

+type: select

+options:

+ - "None"

+ - "Modulating hot gas reheat coil"

+ - "Two-position hot gas reheat coil"

+ - "Electric reheat"

+default: "None"

+```

+### Where hot gas reheat is furnished, the unit controls shall run the compressor for dehumidification on a space or return air humidity signal.

+### Where hot gas reheat is furnished, the reheat shall be modulated or staged to hold the supply air temperature within the simultaneous heating and cooling limits [[parameter: adopted-energy-code]] permits.

+### Hot gas reheat recovers the heat the condenser would otherwise reject and uses it to warm the overcooled air leaving the evaporator, so the unit can keep dehumidifying after the space has reached its temperature setpoint without adding a heating input. Spaces with a high latent load and a low sensible load, and units with a high outdoor air fraction in a humid climate, are where the provision earns its cost; a unit serving a dry-climate office does not use it. {note}

+# Heating {toc}

+## Heating Source {toc}

+### The heating source integral to the unit shall be as indicated in the datasheet.

+```datasheet

+label: Heating Source

+type: select

+options:

+ - "No integral heating section"

+ - "Natural gas-fired"

+ - "Propane-fired"

+ - "Electric resistance"

+ - "Reverse-cycle heat pump"

+ - "Hot water coil"

+ - "Steam coil"

+```

+### The heating source is independent of the cooling configuration, the economizer, and the supply fan control, and no combination of those selections constrains it. {note}

+### No heating source is the norm across projects. Gas heat is common where gas is at the site and the heating load is large, electric resistance where gas is not available or the load is small, a heat pump where the project is electrifying or the climate is mild, and a hydronic coil where a heating plant already serves the building; each is a live choice and the datasheet takes no side. {note}

+## Gas-Fired Heating Section {toc}

+### Requirements in this article apply where the datasheet selects a natural gas-fired or propane-fired heating source, or a gas-fired supplemental heat source.

+### The gas heating input of each unit shall be as indicated in the datasheet.

+```datasheet

+label: Gas Heating Input

+type: range

+unit: MBH

+drawing_ref: "the mechanical equipment schedule"

+options:

+ min: 30

+ max: 2000

+ step: 5

+default: deferred

+```

+### The gas heat exchanger material shall be as indicated in the datasheet.

+```datasheet

+label: Gas Heat Exchanger Material

+type: select

+options:

+ - "Aluminized steel"

+ - "Type 409 stainless steel"

+ - "Type 304 stainless steel"

+ - "Type 316 stainless steel"

+default: "Aluminized steel"

+```

+### The gas heating capacity control shall be as indicated in the datasheet.

+```datasheet

+label: Gas Heating Capacity Control

+type: select

+options:

+ - "Single stage"

+ - "Two stages"

+ - "Modulating"

+```

+### The low-fire input of a staged or modulating burner shall be not more than the percentage of full input indicated in the datasheet.

+```datasheet

+label: Maximum Low-Fire Gas Input as a Percentage of Full Input

+type: range

+unit: '%'

+options:

+ min: 10

+ max: 100

+ setpoints: [10, 20, 25, 33, 40, 50, 65, 100]

+```

+### The thermal efficiency of the gas heating section shall be not less than the value indicated in the datasheet.

+```datasheet

+label: Minimum Gas Heating Thermal Efficiency

+type: range

+unit: '%'

+derived: "the minimum [[parameter: adopted-energy-code]] and 10 CFR Part 431 require for a warm-air furnace of the unit's heating input"

+options:

+ min: 78

+ max: 97

+ setpoints: [78, 80, 81, 82, 90, 95, 97]

+default: derived

+```

+### The gas supply pressure available at each unit connection shall be as indicated in the datasheet.

+```datasheet

+label: Gas Supply Pressure at the Unit Connection

+type: range

+unit: in. w.c.

+drawing_ref: "the gas piping drawings"

+options:

+ min: 3.5

+ max: 14

+ step: 0.5

+default: deferred

+```

+### The unit gas train shall be rated for the gas supply pressure available at the unit connection.

+### The burner shall be furnished with electronic ignition, flame supervision, a redundant gas valve, a high-limit thermal cutout, and a rollout switch.

+### The burner and gas train shall be certified to ANSI Z21.47 / CSA 2.3 as an assembly.

+### The heat exchanger shall be furnished with an induced-draft combustion blower and a proof-of-draft switch that prevents ignition without combustion airflow.

+### Where a modulating or condensing heat exchanger is furnished, the flue products shall be handled and the flue condensate drained as the listing requires.

+### Flue condensate shall be neutralized before it enters a drain that the adopted plumbing code requires to be protected.

+### Aluminized steel is a carbon steel sheet with an aluminum-silicon coating, and it holds up in a heat exchanger that runs hot and dry. A heat exchanger that sees flue gas condensation, which happens at high turndown, on a cold-climate unit with a large outdoor air fraction, or wherever the entering air is cold enough to drop the flue below its dew point, corrodes an aluminized surface from the inside; the stainless grades resist that at a higher cost, with the higher grades reserved for corrosive combustion air or a condensing design. {note}

+### Turndown decides how the section behaves at part load. A single-stage burner delivers full input in short cycles, which swings the supply air temperature and shortens the life of the ignition components; a modulating burner holds a steady supply temperature and is the usual pairing with a variable-air-volume fan, where the airflow across the heat exchanger changes and a fixed input would overheat it at low flow. {note}

+## Electric Resistance Heating Section {toc}

+### Requirements in this article apply where the datasheet selects an electric resistance heating source or an electric resistance supplemental heat source.

+### The electric heating capacity of each unit shall be as indicated in the datasheet.

+```datasheet

+label: Electric Heating Capacity

+type: range

+unit: kW

+drawing_ref: "the mechanical equipment schedule"

+options:

+ min: 2

+ max: 300

+ step: 0.5

+default: deferred

+```

+### The electric heating capacity control shall be as indicated in the datasheet.

+```datasheet

+label: Electric Heating Capacity Control

+type: select

+options:

+ - "Single stage"

+ - "Two stages"

+ - "Three or more stages"

+ - "Modulating by silicon-controlled rectifier"

+```

+### Electric heating elements shall be open-coil nickel-chromium or sheathed elements listed as part of the unit, furnished with a primary automatic-reset thermal cutout and a secondary manual-reset thermal cutout.

+### Electric heating elements shall be interlocked with the supply fan so that the elements cannot be energized without proven airflow.

+### The electric heater airflow interlock shall be hardwired independently of the unit controller and the building automation system.

+### Where the electric heater is furnished with its own power connection, the heater and the unit shall each be furnished with their own disconnecting means.

+### An airflow interlock that depends on the controller fails in the one scenario it exists for, which is the controller being offline while the elements have power. The hardwired path is what makes the interlock a safety rather than a sequence. {note}

+## Heat Pump Heating {toc}

+### Requirements in this article apply where the datasheet selects a reverse-cycle heat pump heating source.

+### Compressor heating shall continue in operation down to the outdoor temperature indicated in the datasheet.

+```datasheet

+label: Minimum Outdoor Temperature for Compressor Heating Operation

+type: range

+unit: °F

+options:

+ min: -25

+ max: 45

+ setpoints: [-25, -15, -5, 0, 5, 10, 17, 25, 35, 45]

+```

+### The integrated heating capacity at the compressor heating operation limit shall be stated in the submittal.

+### The supplemental heat source shall be as indicated in the datasheet.

+```datasheet

+label: Heat Pump Supplemental Heat Source

+type: select

+options:

+ - "None"

+ - "Electric resistance"

+ - "Natural gas-fired"

+ - "Propane-fired"

+ - "Hot water coil"

+```

+### Supplemental heat shall be locked out by the unit controls above the outdoor temperature indicated in the datasheet.

+```datasheet

+label: Supplemental Heat Lockout Outdoor Temperature

+type: range

+unit: °F

+options:

+ min: 10

+ max: 65

+ setpoints: [10, 20, 25, 30, 35, 40, 45, 50, 55, 65]

+```

+### Below the lockout temperature, supplemental heat shall be energized only when compressor heating cannot hold the supply air or space setpoint.

+### The defrost control method shall be as indicated in the datasheet.

+```datasheet

+label: Heat Pump Defrost Control

+type: select

+options:

+ - "Demand defrost initiated by coil temperature and pressure"

+ - "Time-initiated and temperature-terminated defrost"

+```

+### During a defrost cycle the supplemental heat, where furnished, shall be energized as the listing permits so that the supply air is not delivered below the space temperature.

+### The reversing valve shall be energized in the mode the manufacturer designates so that a loss of control signal leaves the unit in that mode, and the mode shall be stated in the submittal.

+### A heat pump's heating capacity falls as the outdoor temperature falls, at the same time as the building's heating load rises, and the two curves cross at the balance point. Below it the compressor cannot carry the load alone and the supplemental source makes up the difference, so the lockout temperature and the balance point are the same number in principle; the lockout is set at or below the balance point to keep the supplemental source from displacing compressor heat that is cheaper to deliver. {note}

+### Demand defrost initiates a cycle when the coil actually frosts rather than on a clock, so a unit in dry cold air defrosts rarely and a unit in damp air near freezing defrosts as often as it needs to; timed defrost is simpler and runs cycles the coil did not need on dry days, each of which reverses the unit into cooling for a few minutes. {note}

+## Hydronic Heating Section {toc}

+### Requirements in this article apply where the datasheet selects a hot water or steam heating source, or a hot water supplemental heat source.

+### The hydronic coil shall be selected at the entering and leaving fluid temperatures indicated in the datasheet.

+```datasheet

+label: Hydronic Heating Coil Entering Fluid Temperature

+type: range

+unit: °F

+drawing_ref: "the mechanical equipment schedule"

+options:

+ min: 90

+ max: 220

+ step: 5

+default: deferred

+```

+```datasheet

+label: Hydronic Heating Coil Leaving Fluid Temperature

+type: range

+unit: °F

+drawing_ref: "the mechanical equipment schedule"

+options:

+ min: 70

+ max: 210

+ step: 5

+default: deferred

+```

+### The freeze protection method for the hydronic coil shall be as indicated in the datasheet.

+```datasheet

+label: Hydronic Heating Coil Freeze Protection

+type: select

+options:

+ - "Glycol solution in the heating circuit"

+ - "Constant coil flow with a modulating three-way valve"

+ - "Constant coil flow maintained by an injection pump"

+ - "Face and bypass dampers with a constant-capacity coil"

+```

+### A hydronic coil in a rooftop unit sits in the outdoor air path of a cabinet that is itself outdoors, so the coil sees the coldest air the unit ever handles and can see it with the fan off. Every method in the field is a way of keeping fluid moving through every tube or of lowering its freezing point, and a two-way valve throttled to a trickle on the coldest night is the arrangement that splits the coil. {note}

+### Coil connections shall pass through the cabinet in a gasketed, insulated penetration.

+### Piping serving a hydronic coil shall be independently supported so that no part of its weight or thermal movement is carried by the coil header.

+### Steam coils shall be of distributing tube non-freeze construction.

+### Steam coils shall be pitched toward the return connection.

+### Each steam coil shall be trapped separately from every other coil.

+# Economizer and Ventilation {toc}

+## Air-Side Economizer {toc}

+### The air-side economizer provision shall be as indicated in the datasheet.

+```datasheet

+label: Air-Side Economizer

+type: radio

+derived: "the economizer requirement [[parameter: adopted-energy-code]] sets for the unit's cooling capacity in [[parameter: climate-zone]], including the exceptions that code lists"

+options:

+ - "Air-side economizer furnished"

+ - "No air-side economizer"

+default: derived

+```

+### Where an economizer is furnished, the outdoor air damper, the return air damper, and the relief path shall be sized for 100% of the design supply airflow.

+### Where an economizer is furnished, the unit shall modulate from the minimum outdoor airflow to full outdoor air.

+### Where an economizer is furnished, it shall be integrated with mechanical cooling so that the compressors stage on to supplement outdoor air cooling rather than being locked out while the economizer is active.

+### Where the datasheet selects no economizer on a unit for which the adopted energy code would otherwise require one, the exception relied on shall be identified in the submittal.

+### The energy code requires an economizer above a capacity threshold that varies with climate zone, and it lists exceptions for units that can show an equivalent efficiency credit, that serve spaces with humidity requirements the outdoor air would violate, and a handful of other cases. Whether a given unit needs one is therefore a lookup on capacity and zone, which is why it is derived; the exceptions are what the submittal documents when a project opts out. {note}

+### The economizer relief arrangement shall be as indicated in the datasheet.

+```datasheet

+label: Economizer Relief Arrangement

+type: select

+options:

+ - "Barometric relief damper in the unit"

+ - "Powered exhaust fan in the unit"

+ - "Return fan with modulating relief damper in the unit"

+ - "Building relief by others"

+```

+### Where a powered exhaust or return fan is furnished, it shall be controlled to hold the building pressure setpoint across the full economizer range.

+### Where a powered exhaust or return fan is furnished, it shall be interlocked to stop when the supply fan stops.

+### Air admitted through the outdoor air damper has to leave the building, and at full economizer that is the entire supply airflow. A barometric damper relieves what the building's pressure will push through it, which is enough for a leaky single-story building and not enough for a tight one, where the pressure rises until doors stand open; a powered relief fan moves the air regardless of building pressure, at the cost of a second motor and a control loop. {note}

+## Economizer High-Limit Control {toc}

+### The economizer high-limit shutoff control shall be as indicated in the datasheet.

+```datasheet

+label: Economizer High-Limit Shutoff Control

+type: select

+options:

+ - "Fixed dry-bulb"

+ - "Differential dry-bulb"

+ - "Fixed enthalpy with a fixed dry-bulb limit"

+ - "Differential enthalpy with a fixed dry-bulb limit"

+ - "Electronic enthalpy curve"

+```

+### The high-limit control type shall be one [[parameter: adopted-energy-code]] permits for [[parameter: climate-zone]].

+### Where a fixed dry-bulb limit applies, its setpoint shall be as indicated in the datasheet.

+```datasheet

+label: Fixed Dry-Bulb High-Limit Setpoint

+type: range

+unit: °F

+derived: "the fixed dry-bulb high-limit setpoint [[parameter: adopted-energy-code]] prescribes for [[parameter: climate-zone]]"

+options:

+ min: 55

+ max: 80

+ step: 1

+default: derived

+```

+### Economizer sensors shall be mounted where they read the condition being controlled, with the outdoor sensor shielded from solar gain, clear of the condenser discharge, and away from exhaust and relief openings.

+### The high limit exists to stop the economizer before free cooling becomes an added cooling load. A dry-bulb limit compares only temperature, so in a humid climate it can admit outdoor air that is cooler than the return air and carries far more moisture, which the coil then has to remove. An enthalpy limit compares total heat and closes that gap, at the cost of a humidity sensor whose drift is harder to notice than a temperature sensor's. Which types are permitted, and at what setpoint, is set by the energy code for the climate zone rather than by preference. {note}

+## Economizer Dampers and Fault Detection {toc}

+### The outdoor air and relief damper leakage class shall be as indicated in the datasheet, tested in accordance with ANSI/AMCA 500-D.

+```datasheet

+label: Outdoor Air and Relief Damper Leakage Class

+type: select

+derived: "the maximum damper leakage [[parameter: adopted-energy-code]] permits for the damper's service in [[parameter: climate-zone]]"

+options:

+ - "AMCA Class 1A"

+ - "AMCA Class 1"

+ - "AMCA Class 2"

+ - "AMCA Class 3"

+default: derived

+```

+### Damper blades shall be airfoil or double-skin construction with blade edge seals and jamb seals.

+### Felt or fibrous seals shall not be furnished on any damper in the unit.

+### Damper actuators shall be direct-coupled to the damper shaft.

+### Damper actuators shall be sized with not less than 25% reserve torque at the unit's design static pressure.

+### Outdoor air and relief dampers shall drive to the closed position on loss of power or control signal.

+### Economizer fault detection and diagnostics shall be as indicated in the datasheet.

+```datasheet

+label: Economizer Fault Detection and Diagnostics

+type: radio

+derived: "the fault detection and diagnostics requirement [[parameter: adopted-energy-code]] sets for economizer-equipped units of the unit's cooling capacity"

+options:

+ - "Fault detection and diagnostics furnished"

+ - "Not furnished"

+default: derived

+```

+### Where fault detection and diagnostics are furnished, the unit controller shall detect and report a failed or out-of-range changeover sensor, a damper that does not modulate, excess or deficient outdoor air, an economizer disabled when it should be enabled, and mechanical cooling operating when the economizer alone could meet the load.

+### The fault reporting paths shall be as indicated in the datasheet.

+```datasheet

+label: Economizer Fault Reporting Paths

+type: checkbox

+options:

+ - "Local annunciation at the unit controller"

+ - "Report to the building automation system"

+default:

+ - "Local annunciation at the unit controller"

+ - "Report to the building automation system"

+```

+### A leaking outdoor air damper admits unconditioned air during every hour of mechanical cooling and heating, and a stuck economizer damper either wastes the free cooling it exists for or admits full outdoor air in January. Neither failure is visible from the space, which is the argument for diagnostics: an economizer that fails silently costs energy for years, and the diagnostics are what make the failure a service call instead of a utility bill. {note}

+## Minimum Outdoor Air {toc}

+### Each unit shall deliver not less than the minimum outdoor airflow indicated in the datasheet at every supply airflow in its operating range.

+```datasheet

+label: Minimum Outdoor Airflow

+type: range

+unit: cfm

+drawing_ref: "the mechanical equipment schedule"

+options:

+ min: 0

+ max: 30000

+ step: 25

+default: deferred

+```

+### The minimum outdoor air control method shall be as indicated in the datasheet.

+```datasheet

+label: Minimum Outdoor Air Control Method

+type: select

+options:

+ - "Fixed minimum position stop on the outdoor air damper"

+ - "Separate minimum outdoor air damper sized for the minimum airflow"

+ - "Outdoor airflow measuring station with closed-loop damper control"

+```

+### Where an outdoor airflow measuring station is furnished, it shall be rated in accordance with ANSI/AMCA 610.

+### Where an outdoor airflow measuring station is furnished, it shall be accurate across the range from the minimum outdoor airflow to the full economizer airflow.

+### Where the ventilation rate is set by a fixed minimum position, the position shall be established during balancing at the design supply airflow and recorded in the balance report.

+### The outdoor air fraction at a fixed damper position changes with supply fan speed and with the pressure difference across the damper, so a fixed stop holds the ventilation rate only under the conditions it was set at. On a constant-volume unit those conditions persist; on a unit whose fan slows at part load the outdoor airflow falls with it, which is why a measured closed loop or a separate small damper is the arrangement that keeps a variable-air-volume unit ventilating. {note}

+### Outdoor air intakes shall be furnished with a rain hood, a bird screen, and a moisture eliminator or drainable hood arrangement sized so that water is not carried into the unit at the design wind-driven rain condition.

+## Demand-Controlled Ventilation {toc}

+### Demand-controlled ventilation shall be as indicated in the datasheet.

+```datasheet

+label: Demand-Controlled Ventilation

+type: radio

+derived: "the demand-controlled ventilation requirement [[parameter: adopted-energy-code]] sets for the occupant density, floor area, and outdoor airflow of the spaces the unit serves"

+options:

+ - "Demand-controlled ventilation furnished"

+ - "Not furnished"

+default: derived

+```

+### Where demand-controlled ventilation is furnished, the sensing basis shall be as indicated in the datasheet.

+```datasheet

+label: Demand-Controlled Ventilation Sensing

+type: select

+options:

+ - "Carbon dioxide sensor in the space"

+ - "Carbon dioxide sensor in the return air"

+ - "Occupancy sensor input"

+ - "Occupancy schedule from the building automation system"

+```

+### Demand-controlled ventilation shall reset the outdoor airflow between the minimum required by ANSI/ASHRAE 62.1 for the area served and the design minimum.

+### Demand-controlled ventilation shall not reduce outdoor air below the area-based component of the ventilation rate.

+### Ventilation air is sized for the design occupancy, and most spaces are below design occupancy most of the time. Resetting on a measured occupancy signal recovers the energy of conditioning air for people who are not there while holding the area-based floor that dilutes contaminants the building itself emits. A return air sensor reads a blend of every space the unit serves, so it resets on the average and can under-ventilate the fullest room, which is why a space sensor is the usual choice for a unit serving one dense room and a return sensor for a unit serving many similar ones. {note}

+## Exhaust Air Energy Recovery {toc}

+### Exhaust air energy recovery shall be as indicated in the datasheet.

+```datasheet

+label: Exhaust Air Energy Recovery

+type: radio

+derived: "the energy recovery requirement [[parameter: adopted-energy-code]] sets for the unit's design supply airflow, outdoor air fraction, and operating hours in [[parameter: climate-zone]]"

+options:

+ - "Energy recovery furnished"

+ - "Not furnished"

+default: derived

+```

+### Where energy recovery is furnished, the recovery device shall be as indicated in the datasheet.

+```datasheet

+label: Energy Recovery Device

+type: select

+options:

+ - "Total energy rotary wheel integrated in the unit"

+ - "Sensible-only rotary wheel integrated in the unit"

+ - "Fixed-plate exchanger integrated in the unit"

+ - "Recovery by a separate unit upstream of the outdoor air intake"

+```

+### Where energy recovery is furnished, its performance shall be rated in accordance with ANSI/AHRI 1060 and tested in accordance with ANSI/ASHRAE 84.

+### Where energy recovery is furnished, the enthalpy recovery ratio at design conditions shall be not less than the value indicated in the datasheet.

+```datasheet

+label: Minimum Enthalpy Recovery Ratio

+type: range

+unit: '%'

+derived: "the minimum enthalpy recovery ratio [[parameter: adopted-energy-code]] requires where energy recovery is required"

+options:

+ min: 0

+ max: 85

+ step: 5

+default: derived

+```

+### Where energy recovery is furnished, the pressure drop the device adds to the supply and exhaust airstreams shall be included in the fan selections and stated in the submittal.

+### Where energy recovery is furnished, a means of reducing or stopping recovery shall be provided so that the device does not transfer heat into the supply airstream when the economizer is calling for free cooling.

+### Where energy recovery is furnished, the frost control method and the outdoor temperature at which it initiates shall be stated in the submittal.

+### Where recovery is by a separate unit upstream, that unit shall conform to [[sync/energy-recovery-ventilators]] or [[sync/dedicated-outdoor-air-systems]] as applicable.

+### Where recovery is by a separate unit upstream, the rooftop unit shall be selected at the entering air condition the recovery unit delivers.

+### A recovery device collects its energy by spending fan power continuously on both airstreams, so it pays where the outdoor and exhaust conditions are far apart and the outdoor air fraction is high, and it costs about the same either way. That is why the energy code triggers it on airflow, outdoor air fraction, and climate zone together rather than on any one of them. {note}

+# Supply Fan and Motor {toc}

+## Airflow and Static Pressure {toc}

+### Each unit shall deliver the design supply airflow indicated in the datasheet at the design external static pressure, at the site elevation, and with the filters at their change-out resistance.

+```datasheet

+label: Design Supply Airflow

+type: range

+unit: cfm

+drawing_ref: "the mechanical equipment schedule"

+options:

+ min: 600

+ max: 60000

+ step: 50

+default: deferred

+```

+```datasheet

+label: Design External Static Pressure

+type: range

+unit: in. w.g.

+drawing_ref: "the mechanical equipment schedule"

+options:

+ min: 0.1

+ max: 5

+ step: 0.05

+default: deferred

+```

+### The external static pressure is the resistance of the ductwork, accessories, and terminals beyond the unit connection; the unit's own sections are inside it and are the manufacturer's to account for. {note}

+### The manufacturer shall add the internal resistance of every furnished section, including the economizer, the heating section, the energy recovery device, and the filters at change-out resistance, to the external static pressure to establish the total static pressure at which the fan is selected.

+### A rooftop unit's published airflow at a stated external static pressure already accounts for the unit's own casing and a clean filter, and the two items most often left out are the field-installed heating section on a unit ordered without one and the filter loading between changes. A fan selected with clean filters delivers design airflow on the day the filters are changed and less every day after. {note}

+## Supply Fan Volume Control {toc}

+### The supply fan volume control shall be as indicated in the datasheet.

+```datasheet

+label: Supply Fan Volume Control

+type: select

+options:

+ - "Constant volume at a single speed"

+ - "Two speeds staged with cooling capacity"

+ - "Multiple speeds staged with cooling and heating capacity"

+ - "Variable air volume by variable frequency drive"

+ - "Variable air volume by electronically commutated motor"

+```

+### The supply fan control shall provide not less than the number of speeds or the modulation range [[parameter: adopted-energy-code]] requires for the unit's cooling capacity and configuration.

+### Where variable air volume is selected, the fan shall be controlled to a duct static pressure setpoint that is reset on terminal demand where the building automation system provides the signal.

+### Where variable air volume is selected, the fan shall operate stably without surge or stall down to the minimum airflow the connected terminals require.

+### Variable frequency drives furnished with the unit shall conform to [[sync/hvac-variable-frequency-drives]].

+### A variable frequency drive furnished with the unit shall be factory-mounted outside the airstream in a compartment ventilated for the drive's heat at [[parameter: site-ambient-temperature-maximum]].

+### A variable frequency drive furnished with the unit shall be accessible without opening a section that is under pressure during operation.

+### The energy code has moved this decision from a preference to a floor. Above a capacity threshold a direct-expansion unit is required to reduce fan airflow at part cooling load, which a single-speed fan cannot do, so the floor is at least two speeds and the choice above it is between staged speeds, which are cheap and coarse, and continuous modulation, which follows the load and is what a variable-air-volume system needs. {note}

+## Supply Fan Construction {toc}

+### The supply fan wheel type shall be as indicated in the datasheet.

+```datasheet

+label: Supply Fan Wheel Type

+type: select

+options:

+ - "Forward-curved centrifugal"

+ - "Backward-curved centrifugal"

+ - "Airfoil centrifugal"

+ - "Unhoused plenum fan"

+default: manufacturer

+```

+### Where the datasheet leaves the wheel type to the manufacturer, the manufacturer shall state the wheel type furnished in the submittal.

+### The supply fan drive arrangement shall be as indicated in the datasheet.

+```datasheet

+label: Supply Fan Drive Arrangement

+type: radio

+options:

+ - "Direct drive"

+ - "Belt drive"

+```

+### Where a belt drive is furnished, the fan shall be provided with an adjustable motor base, a belt guard with a tachometer opening, and a sheave combination that produces the design fan speed within ±5%.

+### Where a forward-curved wheel is furnished, the motor shall be sized for the power the fan draws at the point where the fan curve crosses the system curve with clean filters and every damper full open.

+### Fan wheels shall be dynamically balanced as an assembly.

+### Fan balance shall be verified by measurement at the bearings during the factory run test.

+### Fan performance shall be rated from tests in accordance with ANSI/AMCA 210.

+### The wheel type is a property of the manufacturer's product line at a given capacity more than a project choice: small units are built around forward-curved wheels because they are compact and quiet at low speed, and larger units around backward-curved, airfoil, or plenum wheels because those reach their efficiency at the pressures a large duct system imposes. A project asserts a wheel type only where a sound or efficiency target requires one. {note}

+### A forward-curved wheel's power rises continuously with airflow, so a system that turns out less resistive than calculated lets the fan run out along its curve into motor overload; the backward-curved family has a power curve that peaks and falls, which is the property called non-overloading. Sizing the forward-curved motor at the full-open condition is what keeps that difference from becoming a tripped overload during balancing. {note}

+## Fan Motor {toc}

+### Motor voltage and phase shall match the branch circuit serving the unit as indicated in the datasheet.

+```datasheet

+label: Unit Supply Voltage

+type: range

+unit: V

+drawing_ref: "the electrical drawings and panel schedules"

+options:

+ min: 208

+ max: 575

+ setpoints: [208, 230, 460, 575]

+default: deferred

+```

+```datasheet

+label: Unit Supply Phase

+type: radio

+drawing_ref: "the electrical drawings and panel schedules"

+options:

+ - "Single phase, 1Φ"

+ - "Three phase, 3Φ"

+default: deferred

+```

+### Any discrepancy between the mechanical schedule and the electrical documents on the voltage or phase serving a unit shall be resolved before the unit is released for fabrication.

+### A single-phase unit shall be furnished only where the electrical documents show single-phase service to that unit and the manufacturer offers the scheduled capacity in single-phase construction.

+### Motors shall conform to [[sync/electric-motors]].

+### Motors shall meet the NEMA Premium efficiency level of NEMA MG 1 where a motor of that size and enclosure is covered by that level.

+### Motors shall be selected so that the nameplate power is not exceeded at any operating point the fan can reach with clean filters and every damper full open.

+### Motors operated from a variable frequency drive shall be rated for inverter duty in accordance with NEMA MG 1 Part 31.

+### Single-phase construction is offered on the smallest units in a product line and stops being offered as the capacity rises, so the phase is decided by the building's service at each unit rather than by a project-wide policy, and the size limit is the manufacturer's rather than this standard's. The recurring coordination failure is a mechanical schedule naming one utilization voltage while the panel schedule serving the unit carries another, discovered when the unit arrives. {note}

+# Sound {toc}

+## Sound Rating Basis {toc}

+### Outdoor radiated sound power shall be rated under the program indicated in the datasheet.

+```datasheet

+label: Outdoor Sound Rating Program

+type: radio

+derived: "the unit's cooling capacity, with units below 135,000 Btu/h rated under AHRI 270 and 135,000 Btu/h and above under AHRI 370"

+options:

+ - "AHRI 270"

+ - "AHRI 370"

+default: derived

+```

+### Supply discharge and return inlet sound power shall be reported in each of the eight octave bands from 63 Hz through 8,000 Hz.

+### The A-weighted outdoor sound power level of each unit shall not exceed the value indicated in the datasheet.

+```datasheet

+label: Maximum A-Weighted Outdoor Sound Power Level

+type: range

+unit: dB

+options:

+ min: 60

+ max: 110

+ step: 1

+```

+### Where the datasheet does not state a maximum outdoor sound power level, the manufacturer shall state the rated value in the submittal and the design team shall confirm it against the property line and adjacent occupancy criteria stated in the Contract Documents.

+### Where the unit serves or adjoins a space with a stated noise criterion, the design team shall carry the submitted discharge and inlet sound power levels through the attenuation of the connected duct path to the receiving room and shall confirm the result against the criterion, with attenuation furnished in accordance with [[sync/hvac-sound-attenuators]] where the criterion is not met.

+### A rooftop unit makes noise in two directions. The condenser fans and compressors radiate to the roof and the neighbors, which is what the outdoor rating captures as a single A-weighted number, and the supply fan sends sound down the duct into the occupied space, which the A-weighted number says nothing about. The duct path is the one occupants complain about, and it needs the octave bands because the low-frequency fan tones that duct lining attenuates poorly are the ones A-weighting discounts most. {note}

+# Cabinet Construction {toc}

+## Cabinet Panels {toc}

+### The cabinet panel construction shall be as indicated in the datasheet.

+```datasheet

+label: Cabinet Panel Construction

+type: select

+options:

+ - "Double-wall insulated panels"

+ - "Double-wall insulated panels with a thermally broken frame"

+ - "Single-wall panels with an interior insulation liner"

+```

+### The cabinet construction selected in the datasheet shall apply to every unit whose nominal cooling capacity is at or above the capacity indicated in the datasheet.

+```datasheet

+label: Nominal Cooling Capacity At and Above Which the Selected Cabinet Construction Applies

+type: range

+unit: tons

+options:

+ min: 2

+ max: 50

+ setpoints: [2, 3, 5, 7.5, 10, 12.5, 15, 20, 25, 30, 40, 50]

+```

+### Units below the capacity threshold may be furnished in the manufacturer's published cabinet construction for their capacity.

+### Where the datasheet does not state a capacity threshold, the selected cabinet construction shall apply to every unit on the project.

+### Cabinet panels in every section that carries conditioned air shall be insulated to a thermal resistance not less than the value indicated in the datasheet.

+```datasheet

+label: Minimum Cabinet Panel Thermal Resistance

+type: range

+unit: hr·ft²·°F/Btu

+options:

+ min: 2

+ max: 15

+ step: 0.5

+```

+### Where the datasheet does not state a thermal resistance, the manufacturer shall state the thermal resistance of the panel furnished and shall confirm that the exterior surface stays above the dew point of the outdoor air at the design cooling condition.

+### Insulation in the airstream shall be faced, coated, or encapsulated so that fibers are not eroded into the supply air at the maximum velocity the section sees.

+### Double-wall construction is offered on mid-size and large units and is generally not offered below a capacity that varies by product line, so a project-wide requirement for it is really a requirement for the larger units on the roof, and the threshold field is how the project says where the line falls without editing the standard. A double-wall panel keeps the insulation out of the airstream, cleans without eroding, and stiffens the cabinet; a single-wall liner does the thermal job at lower cost and leaves the liner facing exposed. {note}

+### The cabinet structure shall be galvanized steel conforming to ASTM A653 with a G90 coating designation as a minimum.

+### The unit base shall be a full-perimeter rail that supports the unit on the curb without point loads on the cabinet panels.

+### The cabinet shall be arranged so that rainwater drains from every roof and panel surface and does not collect on the cabinet or run into the outdoor air intake.

+## Exterior Finish {toc}

+### Exterior cabinet panels shall receive a factory-applied finish that withstands salt spray exposure in accordance with ASTM B117 for not less than the duration indicated in the datasheet without red rust or blistering.

+```datasheet

+label: Minimum Exterior Finish Salt Spray Exposure

+type: range

+unit: hours

+options:

+ min: 500

+ max: 3000

+ setpoints: [500, 750, 1000, 1500, 2000, 2500, 3000]

+```

+### Where the datasheet does not state a salt spray exposure, the manufacturer shall state in the submittal the finish system furnished and the exposure it has been tested to.

+### Exposed fasteners, hinges, latches, and hardware shall be stainless steel or a coated steel with equivalent corrosion resistance.

+### Cut edges, field-drilled penetrations, and fasteners shall receive a zinc-rich touch-up coating before the unit is placed in service.

+### The salt spray rating is a comparative durability number rather than a service life, and the same finish that passes a short exposure on an inland roof fails within a few years on a coastal one. The number is the lever a project has, so it is stated here as a duration and selected by the exposure at the site rather than defaulted. {note}

+## Access Panels {toc}

+### Access shall be provided to the filter section, the evaporator coil and drain pan, the supply fan and motor, the compressor compartment, the heating section, the economizer dampers and actuators, and the control panel.

+### Each access shall permit service of the component behind it without removing the unit from the curb.

+### The access panel construction shall be as indicated in the datasheet.

+```datasheet

+label: Access Panel Construction

+type: select

+options:

+ - "Hinged doors with quarter-turn latches"

+ - "Hinged doors with compression latches"

+ - "Removable gasketed panels with captive fasteners"

+```

+### Access panels and doors shall be gasketed so that they seal against air leakage at the cabinet pressure in every operating mode.

+### Panels that must be removed to service a component shall be light enough for one person to handle on a roof, or shall be hinged.

+### Access panels shall be labeled on the exterior with the section behind them.

+## Duct Connection Orientation {toc}

+### The supply and return duct connection orientation shall be as indicated in the datasheet.

+```datasheet

+label: Duct Connection Orientation

+type: radio

+options:

+ - "Vertical, through the curb"

+ - "Horizontal, from the unit end or side"

+default: "Vertical, through the curb"

+```

+### Where horizontal connections are selected, the supply and return openings shall be furnished with weathertight flanged collars.

+### Where horizontal connections are selected, the openings in the unit base shall be closed and insulated.

+### Vertical connections put the ductwork inside the curb and through the roof beneath the unit, so the roof penetration is the curb itself and the duct is never outdoors; horizontal connections leave the ductwork exposed on the roof between the unit and its own penetration, which is why they are the arrangement for a unit that sits on a rail or a frame rather than a curb, or for a replacement whose existing ductwork already arrives that way. {note}

+# Filtration {toc}

+## Filter Efficiency and Depth {toc}

+### Filter efficiency shall be rated in accordance with ANSI/ASHRAE 52.2.

+### Filters shall have not less than the efficiency indicated in the datasheet.

+```datasheet

+label: Filter Efficiency

+type: select

+options:

+ - "MERV 8"

+ - "MERV 10"

+ - "MERV 11"

+ - "MERV 13"

+ - "MERV 14"

+```

+### Air delivered to an occupiable space shall pass through filtration of not less than MERV 8 upstream of the evaporator coil and every other wetted surface, in accordance with ANSI/ASHRAE 62.1.

+### The filter depth shall be as indicated in the datasheet.

+```datasheet

+label: Filter Depth

+type: range

+unit: in.

+options:

+ min: 1

+ max: 4

+ setpoints: [1, 2, 4]

+```

+### The fan selection shall accommodate the resistance of the selected filters at their change-out condition without falling below the design airflow.

+### The submittal shall state the initial resistance and the recommended change-out resistance of the selected filter at the design face velocity.

+### Filter efficiency and fan power are coupled. Moving from MERV 8 to MERV 13 adds a few tenths of an inch of water gauge across the filter bank at the change-out condition, and that increment is paid by the fan for the life of the unit; a deeper filter of the same rating holds more dust and loads more slowly, which lengthens the change interval and lowers the average resistance. Which rating a project wants follows from its air quality target and from what the fan on a small unit can carry. {note}

+### Filter media shall be listed to UL 900.

+## Filter Rack and Access {toc}

+### The filter rack shall hold the filters against a gasketed seating frame so that no air path exists around the media.

+### Filters shall be removable without tools.

+### The filter section shall be accessible through its own access panel or door without disturbing the coil, the fan, or the electrical compartment.

+### Filter face velocity at design airflow shall not exceed the velocity at which the selected media is rated.

+### Bypass around the media is the dominant filtration defect in installed units, and it is invisible at every point except a measurement of what reaches the space. A rack that lets filters rattle in their track delivers an in-place efficiency far below the media rating, because unfiltered air is a parallel path with almost no resistance while the media path has a great deal. {note}

+# Drain Pan and Condensate {toc}

+## Drain Pan Construction {toc}

+### A drain pan shall be furnished beneath the evaporator coil and beneath every other section in which condensate can form, including a hot gas reheat coil and an energy recovery device that can condense.

+### The drain pan material shall be as indicated in the datasheet.

+```datasheet

+label: Drain Pan Material

+type: select

+options:

+ - "Type 304 stainless steel"

+ - "Galvanized steel with a factory-applied corrosion-resistant coating"

+ - "Molded polymer"

+```

+### The drain pan shall extend the full width of the coil and beneath the coil headers and return bends.

+### The drain pan shall extend downstream of the leaving-air face of the coil far enough to capture carryover at the design face velocity.

+### The drain pan shall be sloped in two planes toward the drain connection.

+### The drain pan shall hold no standing water when the unit is not operating.

+### Drain pans shall be insulated on the underside or double-walled where the surface beneath the pan can fall below the dew point of the surrounding air.

+### A drain pan that holds water between cooling cycles is a warm, dark, nutrient-bearing reservoir in the supply airstream, which is the growth condition the ventilation standard's wetted-surface rules are written around. Every geometric requirement on the pan exists to make it empty rather than merely drain, and the material choice is about how the pan ages under a continuous condensate film: a coated steel pan is fine until the coating is scratched, a polymer pan cannot corrode but can crack, and a stainless pan costs more and does neither. {note}

+## Condensate Trap and Drain {toc}

+### The drain pan shall be furnished with a primary drain connection not smaller than 3/4 in. at the low point.

+### The condensate trap arrangement shall be as indicated in the datasheet.

+```datasheet

+label: Condensate Trap

+type: radio

+options:

+ - "Factory-installed trap integral to the unit"

+ - "Field-installed trap by the installing contractor"

+default: "Field-installed trap by the installing contractor"

+```

+### The trap seal depth shall be not less than the maximum negative static pressure at the drain pan, expressed in inches water gauge, plus 1 in.

+### The trap outlet shall be below the pan outlet by not less than twice the maximum negative static pressure at the drain pan, expressed in inches water gauge.

+### The trap shall be furnished with a cleanout or a union that permits disassembly without cutting the drain line.

+### The trap shall be primed at startup.

+### The condensate drain line from the trap shall be routed to an approved point of disposal in accordance with [[sync/condensate-drainage-piping]], with the slope and freeze protection the climate requires.

+### A drain trap on a draw-through unit holds water against the fan, not against a sewer. If the seal is shallower than the negative pressure at the pan, the fan pulls the seal out, the pan stops draining, and the unit draws unfiltered roof air backward through the drain line. The trap is sized from the pan's static pressure rather than from plumbing practice, and it is the one dimension on the unit that changes when the filter rating changes. {note}

+# Roof Curb, Isolation, and Restraint {toc}

+## Roof Curb {toc}

+### Each unit shall be set on a roof curb of the type indicated in the datasheet.

+```datasheet

+label: Roof Curb Type

+type: select

+options:

+ - "Manufacturer's matched insulated curb"

+ - "Manufacturer's matched curb with integral isolation rails"

+ - "Manufacturer's matched curb of seismic-rated construction"

+ - "Adapter curb fitted to an existing curb"

+ - "Curb fabricated by the roofing or sheet metal trade to the manufacturer's curb drawing"

+```

+### Where a curb is fabricated by a trade other than the unit manufacturer, it shall be built to the manufacturer's published curb drawing for the unit furnished.

+### Where a curb is fabricated by a trade other than the unit manufacturer, the fabricating trade shall be responsible for the fit of the unit to the curb and of the curb to the roof structure.

+### Where an adapter curb is furnished, the adapter shall be engineered by the unit manufacturer for the existing curb dimensions.

+### Where an adapter curb is furnished, the Contractor shall field-verify the existing curb dimensions before the adapter is released for fabrication.

+### The curb shall be a welded or mechanically fastened galvanized steel assembly with a continuous wood nailer for roof flashing, internal cross supports beneath the duct openings, insulation on the interior faces, and a gasket at the unit-to-curb joint.

+### The curb height shall be as indicated in the datasheet, measured from the top of the roof deck to the top of the curb.

+```datasheet

+label: Roof Curb Height

+type: range

+unit: in.

+drawing_ref: "the roof curb detail on the contract documents"

+options:

+ min: 8

+ max: 36

+ setpoints: [8, 12, 14, 16, 18, 24, 30, 36]

+default: deferred

+```

+### The curb height shall provide the flashing height above the finished roof surface that [[sync/membrane-roofing]] requires, including the thickness of the roof insulation and any tapered insulation at the curb.

+### The curb shall be set level on the roof structure, shimmed as required over a sloped deck, and fastened to the structure as [[sync/vibration-isolation-and-seismic-restraint]] and the restraint provisions of this standard require.

+### The curb is the interface between three trades. The unit manufacturer sizes it to the unit, the roofer flashes it into the membrane, and the structural engineer checks the framing beneath it, and the curb height is the dimension all three have to agree on before the first one starts. A curb too short for the roof insulation is the classic finding at the preinstallation conference. {note}

+## Vibration Isolation {toc}

+### The vibration isolation arrangement shall be as indicated in the datasheet.

+```datasheet

+label: Vibration Isolation Arrangement

+type: select

+options:

+ - "Unit-integral fan and compressor isolation on a rigid curb"

+ - "Spring isolation rails within the curb"

+ - "Elastomeric isolation rails within the curb"

+ - "Restrained spring isolators beneath a unit set on a structural frame"

+default: "Unit-integral fan and compressor isolation on a rigid curb"

+```

+### Where isolation rails or isolators are furnished, they shall be selected in accordance with [[sync/vibration-isolation-and-seismic-restraint]] for a static deflection not less than the value indicated in the datasheet.

+```datasheet

+label: Minimum Isolator Static Deflection

+type: range

+unit: in.

+options:

+ min: 0.25

+ max: 3

+ setpoints: [0.25, 0.35, 0.75, 1, 1.5, 2, 2.5, 3]

+```

+### Where isolation rails or isolators are furnished, the duct, gas, electrical, and condensate connections to the isolated unit shall be made through flexible elements.

+### Where the datasheet does not state a static deflection, the isolator selection shall be made from the lowest fan operating speed so that the isolation system natural frequency is not more than one third of that speed.

+### Where isolation rails or isolators are furnished, the calculated isolation efficiency at the lowest fan operating speed shall be stated in the submittal.

+### A rooftop unit's fan and compressors are isolated inside the cabinet as built, and for a unit over a heavy deck remote from occupancy that internal isolation is what most projects rely on. A unit over a light long-span roof, or over a noise-sensitive space, transmits what the internal isolators pass into a structure that amplifies it, and an isolation curb breaks that path at the cost of flexible connections at every service and a curb that has to be built for the movement. {note}

+## Seismic and Wind Restraint {toc}

+### Seismic restraint of the unit and curb shall be as indicated in the datasheet.

+```datasheet

+label: Seismic Restraint

+type: radio

+derived: "[[parameter: seismic-design-category]] applied to the unit weight, the component importance factor assigned to the unit, and the attachment height in accordance with ASCE 7 Chapter 13"

+options:

+ - "Engineered seismic restraint of the unit to the curb and the curb to the structure"

+ - "No seismic restraint beyond the manufacturer's attachment hardware"

+default: derived

+```

+### Wind restraint of the unit and curb shall be as indicated in the datasheet.

+```datasheet

+label: Wind Restraint

+type: radio

+derived: "the wind load ASCE 7 Chapter 29 assigns to rooftop equipment at the unit's height and exposure at the site"

+options:

+ - "Engineered wind restraint of the unit to the curb and the curb to the structure"

+ - "No wind restraint beyond the manufacturer's attachment hardware"

+default: derived

+```

+### Where engineered restraint is furnished, the restraints and their anchorage shall be designed by an engineer licensed in the jurisdiction of the project.

+### Where engineered restraint is furnished, the restraint design shall state the forces delivered to the structure.

+### Restraints on an isolated unit shall permit the isolators to function through their normal range and shall engage only under seismic or wind displacement.

+### Restraint details and anchorage shall be as indicated on [[drawing: the structural drawings]].

+### Seismic and wind restraint are two separate calculations that happen to use the same hardware, and a unit that needs neither in one place can need both in another. The unit's own weight resists uplift on a small unit, and the manufacturer's standard clips hold it to the curb in a calm site; a large flat-sided unit on an exposed roof is a sail, and the calculation is what says whether the clips are enough. {note}

+# Electrical Provisions {toc}

+## Power Connection {toc}

+### The unit's minimum circuit ampacity and maximum overcurrent protective device shall be as published by the manufacturer for the configuration furnished, and the branch circuit, feeder, and overcurrent protection serving the unit shall be as indicated on [[drawing: the electrical drawings]].

+### The unit power connection arrangement shall be as indicated in the datasheet.

+```datasheet

+label: Unit Power Connection

+type: radio

+options:

+ - "Single-point power connection for the complete unit including any electric heater"

+ - "Separate power connections for the unit and the electric heater"

+default: "Single-point power connection for the complete unit including any electric heater"

+```

+### The unit disconnecting means shall be as indicated in the datasheet.

+```datasheet

+label: Unit Disconnecting Means

+type: select

+options:

+ - "Factory-installed non-fused disconnect switch"

+ - "Factory-installed fused disconnect switch"

+ - "Factory-installed circuit breaker"

+ - "Field-installed disconnect by the electrical trade"

+```

+### The disconnecting means shall be lockable in the open position and located within sight of the unit in accordance with NFPA 70.

+### Where the disconnect is field-installed, it shall conform to [[sync/enclosed-switches-and-disconnects]].

+### Where the disconnect is field-installed, it shall be mounted on a stand or on the unit at a location the manufacturer permits, clear of every access panel swing.

+### The short-circuit current rating of the unit control panel shall be not less than the available fault current at the unit terminals indicated in the datasheet.

+```datasheet

+label: Available Fault Current at the Unit Terminals

+type: range

+unit: kA

+drawing_ref: "the electrical drawings"

+options:

+ min: 5

+ max: 100

+ setpoints: [5, 10, 14, 18, 22, 25, 35, 42, 50, 65, 100]

+default: deferred

+```

+### Three-phase units shall be furnished with a phase loss and phase reversal monitor that prevents compressor operation on a lost or reversed phase.

+### A scroll compressor pumps in one direction only, and run backward on a reversed phase it makes no pressure, heats rapidly, and can fail within minutes. The phase monitor is what turns a wiring error at the disconnect into a nuisance trip rather than a compressor replacement on the first start. {note}

+## Service Receptacle {toc}

+### A receptacle for servicing the unit shall be provided as indicated in the datasheet and in accordance with NFPA 70.

+```datasheet

+label: Service Receptacle

+type: select

+options:

+ - "Factory-installed ground-fault protected receptacle fed from a separate field branch circuit"

+ - "Factory-installed ground-fault protected receptacle fed through a unit transformer ahead of the unit disconnect"

+ - "Receptacle furnished and installed by the electrical trade within 25 ft of the unit"

+```

+### The receptacle shall remain energized when the unit disconnecting means is open.

+### The receptacle exists so that a technician can run a vacuum pump, a recovery machine, or a light with the unit itself de-energized, which is the condition under which most of the work on a refrigerant circuit is done. A receptacle on the load side of the unit disconnect goes dead at the moment it is needed, which is why the code forbids that arrangement. {note}

+# Controls and Safeties {toc}

+## Unit Control Configuration {toc}

+### The unit control configuration shall be as indicated in the datasheet.

+```datasheet

+label: Unit Control Configuration

+type: select

+options:

+ - "Factory-installed unit controller integrated with the building automation system"

+ - "Factory-installed unit controller operating stand-alone from a space thermostat"

+ - "Factory-installed devices and wiring with control by the building automation system contractor"

+```

+### The party responsible for the sequence of operation shall be identified in the submittal.

+### The sequence of operation shall be reviewed before any control device is released for fabrication.

+### The unit controller shall sequence cooling stages, heating stages, economizer, minimum outdoor air, and the supply fan.

+### The unit controller shall carry the manufacturer's compressor protection logic, including minimum run and off times and anti-short-cycle timing, regardless of which party controls the setpoints.

+### A factory controller arrives tested with the equipment it controls and carries the manufacturer's protective logic, and it also arrives with a fixed sequence and a proprietary tool for changing it. Field-engineered controls put the sequence in one place with the rest of the building and put the responsibility for protecting the compressors on the party that did not build them. The compressor protection has to work regardless of who wrote the sequence, which is why it is required of the unit in every configuration. {note}

+## Building Automation System Interface {toc}

+### The communication interface to the building automation system shall be as indicated in the datasheet.

+```datasheet

+label: Building Automation System Interface

+type: select

+options:

+ - "BACnet MS/TP"

+ - "BACnet/IP"

+ - "Modbus RTU"

+ - "Modbus TCP"

+ - "LonWorks FT-10"

+ - "Hardwired point-to-point interface with no network connection"

+```

+### The interface shall conform to [[sync/building-automation-system]].

+### The manufacturer shall furnish a complete point list for the interface, giving the object name, object type, engineering units, and read or write access for every exposed point.

+### Field control connections shall terminate on a labeled terminal block in a compartment accessible without opening a section that is pressurized during operation.

+### Terminal designations on the unit shall match the submitted wiring diagram and point list.

+### The points exposed to the building automation system shall include those indicated in the datasheet.

+```datasheet

+label: Control Points Exposed to the Building Automation System

+type: checkbox

+options:

+ - "Supply air temperature"

+ - "Return air temperature"

+ - "Mixed air temperature"

+ - "Outdoor air temperature"

+ - "Outdoor air humidity"

+ - "Space or return air carbon dioxide concentration"

+ - "Supply fan command, speed, and status"

+ - "Compressor stage or capacity command and status by circuit"

+ - "Heating stage or modulation command and status"

+ - "Economizer damper position"

+ - "Outdoor air damper position or measured outdoor airflow"

+ - "Economizer fault status"

+ - "Filter differential pressure or change-filter alarm"

+ - "Refrigerant detection alarm"

+ - "Compressor lockout and general alarm status"

+ - "Occupied and unoccupied mode command"

+ - "Supply air temperature and duct static pressure setpoints"

+default:

+ - "Supply air temperature"

+ - "Return air temperature"

+ - "Outdoor air temperature"

+ - "Supply fan command, speed, and status"

+ - "Compressor stage or capacity command and status by circuit"

+ - "Heating stage or modulation command and status"

+ - "Economizer damper position"

+ - "Economizer fault status"

+ - "Filter differential pressure or change-filter alarm"

+ - "Compressor lockout and general alarm status"

+ - "Occupied and unoccupied mode command"

+```

+### Control devices furnished with the unit shall conform to [[sync/hvac-controls-instrumentation]].

+### Control devices furnished with the unit shall be accessible for calibration and replacement from a service position without entering an operating section.

+## Duct Smoke Detection {toc}

+### Duct smoke detection shall be furnished at the locations indicated in the datasheet.

+```datasheet

+label: Duct Smoke Detector Locations

+type: select

+derived: "the unit's supply airflow and return air arrangement against the detector thresholds NFPA 90A and the adopted mechanical code set"

+options:

+ - "Supply air only"

+ - "Supply air and return air"

+ - "None required for the unit"

+default: derived

+```

+### The responsibility for furnishing and installing duct smoke detectors shall be as indicated in the datasheet.

+```datasheet

+label: Duct Smoke Detector Responsibility

+type: select

+options:

+ - "Furnished and installed by the fire alarm contractor"

+ - "Furnished by the fire alarm contractor and installed by the mechanical contractor"

+ - "Furnished and installed by the mechanical contractor"

+ - "Factory-installed by the unit manufacturer"

+```

+### Duct smoke detectors shall be installed in accordance with NFPA 90A, NFPA 72, and the adopted mechanical code.

+### Smoke detection shall shut down the supply fan through a hardwired interlock that does not depend on the unit controller or the building automation system.

+### Smoke detection shall report to the fire alarm system in accordance with [[sync/fire-alarm-systems]].

+### Detector sampling tubes shall span the duct or plenum cross-section.

+### Detector sampling tubes shall be oriented and sized in accordance with the detector manufacturer's instructions for the cross-section they are installed in.

+### The supply detector threshold in the mechanical code is set on airflow and the return detector threshold on airflow and the number of stories served, so for a given unit the locations are a lookup rather than a choice; the responsibility for furnishing them is a genuine project decision that turns on how the fire alarm contract was written. {note}

+## Unit Safety Devices {toc}

+### Each unit shall be furnished with the safety devices the listing requires, including high and low refrigerant pressure cutouts on each circuit, compressor motor overloads, heating section high-limit and rollout devices, and a freeze protection device on any hydronic coil.

+### Every unit with a hydronic coil shall be furnished with a low-limit temperature device downstream of the mixing section, arranged to stop the supply fan, close the outdoor air damper, and open the coil control valve when it trips.

+### A high static pressure safety device shall be furnished in the supply air section of every variable-air-volume unit whose fan can develop a pressure exceeding the pressure class of the connected ductwork.

+### The high static pressure safety device shall stop the supply fan through a hardwired interlock with manual reset.

+### Every safety device that requires manual reset shall be reset only at the unit.

+### The unit controller shall report the trip of every safety device to the building automation system where an interface is furnished.

+### The setpoint of every safety device shall be recorded in the startup report.

+# Factory Testing {toc}

+## Production Run Test {toc}

+### Every unit shall be run-tested at the factory before shipment.

+### The factory tests performed on each unit shall include those indicated in the datasheet.

+```datasheet

+label: Factory Tests Required

+type: checkbox

+options:

+ - "Refrigerant circuit evacuation, charge, and leak test"

+ - "Compressor and condenser fan operation on each stage"

+ - "Refrigerant operating pressures and temperatures recorded on each circuit"

+ - "Supply fan operation with motor current recorded"

+ - "Heating section fired or energized on each stage"

+ - "Economizer damper stroke and fail-position test"

+ - "Safety device trip verification"

+ - "Refrigerant detection system function test"

+ - "Controls point-to-point verification"

+ - "Cabinet water intrusion test"

+default:

+ - "Refrigerant circuit evacuation, charge, and leak test"

+ - "Compressor and condenser fan operation on each stage"

+ - "Refrigerant operating pressures and temperatures recorded on each circuit"

+ - "Supply fan operation with motor current recorded"

+ - "Heating section fired or energized on each stage"

+ - "Economizer damper stroke and fail-position test"

+ - "Safety device trip verification"

+ - "Controls point-to-point verification"

+```

+### A unit that fails any required test shall be corrected and retested.

+### The cost of correcting a failed factory test and of every retest shall be borne by the manufacturer.

+### No unit shall be shipped until every required test has been passed and the results recorded on a report that identifies the unit by serial number.

+### The factory run test is the only opportunity to find a charge, a wiring, or a compressor defect while the unit is on a floor with the parts and the people to fix it. A unit that ships untested is repaired on a roof, by crane, in whatever weather the schedule lands on. {note}

+## Test Witnessing {toc}

+### Factory test witnessing shall be as indicated in the datasheet.

+```datasheet

+label: Factory Test Witnessing

+type: radio

+options:

+ - "Unwitnessed, with a certified test report submitted"

+ - "Witnessed at the factory by the Owner's representative"

+ - "Witnessed remotely by live video with the instrumentation in view"

+default: "Unwitnessed, with a certified test report submitted"

+```

+### Where witnessed testing is selected, the manufacturer shall give not less than ten business days notice of test readiness.

+### Where witnessed testing is selected, the manufacturer shall submit the test procedure for review before the test is scheduled.

+### Where witnessed testing is selected and the unit fails, the cost of the witness attending each retest shall be borne by the manufacturer.

+# Delivery, Storage, and Handling {toc}

+## Units shall be shipped fully assembled, charged, and with every opening covered and sealed against water and debris.

+## Units shall be stored on a level surface, off the ground, in their protective packaging, with the openings sealed, until they are set.

+## Units stored for more than 30 days before setting shall have the crankcase heaters energized where the manufacturer requires it.

+## Units stored for more than 30 days before setting shall have the fan shaft rotated by hand at intervals not exceeding 30 days.

+## Units stored for more than 30 days before setting shall be inspected by the Contractor for water intrusion, corrosion, and pest intrusion before setting.

+## Units shall not be stacked or used as a storage surface.

+## The crane, pick radius, and temporary roof loads shown on the rigging and setting plan shall be reviewed by the structural engineer before the pick.

+## Units damaged in transit, in storage, or in handling shall be repaired or replaced as the Engineer of Record directs in writing.

+## A unit whose refrigerant circuit has been opened by damage shall be evacuated and recharged at the factory or by the manufacturer's representative.

+# Installation {toc}

+## Rigging and Setting {toc}

+### Units shall be rigged using the lifting points, spreader arrangement, and rigging hardware the manufacturer designates.

+### Slings shall not bear against cabinet panels, coils, or the condenser fan guards.

+### Before the pick, the Contractor shall verify that the curb is set, level, flashed, and dried in, that the curb duct openings align with the unit, and that the roof structure and curb have been confirmed adequate for the unit operating weight.

+### The unit shall be set on the curb gasket so that the gasket is continuous and compressed on all four sides.

+### The unit shall be set level within the tolerance the manufacturer publishes so that the drain pan slopes to its connection.

+### Shipping restraints, shipping bolts, and transit blocks on the fan and compressor mounts shall be removed after the unit is set and before the unit is energized.

+### A shipping restraint left on a compressor mount holds the compressor rigid against the base, so the first start delivers the full vibration into the cabinet and into refrigerant tubing that was not designed to flex there. It is a same-week failure rather than a slow one, and the pre-startup inspection exists to catch it. {note}

+## Roofing and Flashing {toc}

+### The curb shall be flashed into the roofing membrane by the roofing installer in accordance with [[sync/membrane-roofing]] and [[sync/sheet-metal-flashing-and-trim]].

+### The curb flashing shall be complete and watertight before the unit is set.

+### Every penetration of the roof for ductwork, gas piping, electrical conduit, condensate drainage, and control wiring shall pass through a flashed curb, sleeve, or pitch pocket.

+### No penetration shall be made through the unit-to-curb gasket line.

+### The Contractor shall sequence the roofing and the setting so that the curb is dried in before the unit is set and the membrane is not damaged by the pick or by traffic around the unit.

+### Where the Contractor is required to restore roofing disturbed by the work, restoration shall match the pre-existing condition recorded in the informational submittal, and where no record was submitted, the Engineer of Record shall make the initial determination of the pre-existing condition.

+## Duct Connections at the Unit {toc}

+### Supply and return ductwork shall connect to the unit in accordance with [[sync/hvac-ductwork]] and the SMACNA HVAC Duct Construction Standards.

+### Connecting ductwork shall be independently supported so that no duct weight is carried by the unit or the curb.

+### Duct connections to an isolated unit shall be made through flexible connectors.

+### Duct transitions at the unit shall not exceed the transition angle at which the fan outlet loss published in the submittal remains valid.

+### Ductwork within the curb shall be sealed to the curb opening so that supply air is not lost into the curb cavity and return air is not drawn from it.

+### A supply duct that leaves the curb into an immediate elbow does not develop the velocity profile the fan was rated with, and the resulting system effect consumes a fraction of the fan's rated pressure. It shows up during balancing as a unit that will not make its airflow at a fan speed the curve says is ample. {note}

+## Utility Connections {toc}

+### Gas piping to each gas-fired unit shall be installed in accordance with [[sync/natural-gas-piping]] or [[sync/fuel-gas-piping]] as applicable to the fuel.

+### Gas piping at each gas-fired unit shall include a shutoff valve, a sediment trap, and a union at the unit connection.

+### Gas piping to each gas-fired unit shall be leak-tested before the burner is fired.

+### Where the gas supply pressure exceeds the rating of the unit gas train, a pressure regulator with its vent piped to the outdoors clear of the outdoor air intake shall be installed ahead of the unit.

+### Electrical connections shall be made in accordance with NFPA 70, and conduit to an isolated unit shall include not less than 18 in. of flexible conduit at the unit.

+### The condensate trap and drain line shall be installed, sloped, and primed before the unit is started in cooling.

+### Control wiring shall be run in the raceway the unit manufacturer designates, segregated from power wiring, and terminated on the labeled terminals shown on the submitted wiring diagram.

+## Service Clearances {toc}

+### The service clearances shown on the reviewed configuration drawing shall be maintained clear of ductwork, piping, conduit, and other equipment after installation.

+### The condenser coil clearance, the filter withdrawal clearance, the compressor compartment access, and the heating section withdrawal path shall remain unobstructed for the life of the installation.

+### Where a service clearance conflicts with other work, the conflict shall be resolved before either is installed, and the Engineer of Record shall make the initial determination of which work relocates.

+### Units shall be located so that the condenser discharge of one unit is not drawn into the condenser intake or the outdoor air intake of another.

+### The outdoor air intake of each unit shall be clear of exhaust fan discharges, plumbing vents, and flue outlets by the distances ANSI/ASHRAE 62.1 and the adopted mechanical code require.

+# Startup, Commissioning, and Balancing {toc}

+## Pre-Startup Inspection {toc}

+### Before any unit is energized, the Contractor shall complete and record the inspection items indicated in the datasheet.

+```datasheet

+label: Pre-Startup Inspection Items

+type: checkbox

+options:

+ - "Roof structure and curb load verified"

+ - "Curb flashing complete and watertight"

+ - "Unit level and drain pan sloping to its connection"

+ - "Unit-to-curb gasket continuous and compressed"

+ - "Shipping restraints removed"

+ - "Fan and compressor mounts free to move"

+ - "Supply and return duct connections complete and sealed"

+ - "Condensate trap installed, sized for the pan static pressure, and primed"

+ - "Electrical connections complete and phase rotation verified"

+ - "Disconnect and service receptacle operable"

+ - "Gas piping connected, leak-tested, and supply pressure verified"

+ - "Filters installed"

+ - "Service clearances verified clear"

+ - "Refrigerant detection sensors in place and dated"

+default:

+ - "Roof structure and curb load verified"

+ - "Curb flashing complete and watertight"

+ - "Unit level and drain pan sloping to its connection"

+ - "Unit-to-curb gasket continuous and compressed"

+ - "Shipping restraints removed"

+ - "Fan and compressor mounts free to move"

+ - "Supply and return duct connections complete and sealed"

+ - "Condensate trap installed, sized for the pan static pressure, and primed"

+ - "Electrical connections complete and phase rotation verified"

+ - "Disconnect and service receptacle operable"

+ - "Filters installed"

+ - "Service clearances verified clear"

+```

+### The inspection record shall mark as not applicable the gas piping items on units without gas-fired heat and the refrigerant detection items on units without a detection system, rather than omitting them.

+## Startup Service {toc}

+### The startup service shall be as indicated in the datasheet.

+```datasheet

+label: Startup Service

+type: select

+options:

+ - "Startup performed by a factory-authorized service representative"

+ - "Startup performed by the installing contractor with factory technical support"

+ - "Startup performed by the installing contractor"

+default: "Startup performed by a factory-authorized service representative"

+```

+### Startup shall verify the refrigerant charge on each circuit against the nameplate and the published subcooling or superheat target, the operation of each compressor and condenser fan on each stage, the heating section on each stage with the input measured on gas-fired units, economizer modulation and changeover, minimum outdoor air, the trip of every safety device at its setpoint, and the refrigerant detection and mitigation sequence where a detection system is furnished.

+### Each safety device shall be tested by driving the condition it senses to its setpoint rather than by simulating the device output.

+### The startup report shall record the measured supply airflow, external static pressure, fan speed, motor current, refrigerant operating pressures and temperatures by circuit, gas input and manifold pressure, and the setpoint of every safety device.

+### Startup on a gas-fired unit includes clocking the gas meter or measuring the manifold pressure to confirm the input, because a burner set up at the factory for sea level and shipped to an elevated site over-fires until the orifice or the manifold pressure is corrected, and over-firing is what cracks a heat exchanger early. {note}

+## Commissioning {toc}

+### The commissioning scope shall be as indicated in the datasheet.

+```datasheet

+label: Commissioning Scope

+type: checkbox

+options:

+ - "Manufacturer startup with a signed report"

+ - "Point-to-point verification of every control device"

+ - "Functional performance testing of the control sequences"

+ - "Verified trip of every safety device at its setpoint"

+ - "Economizer changeover verification across the high-limit setpoint"

+ - "Economizer fault detection verification by induced fault"

+ - "Demand-controlled ventilation response verification"

+ - "Refrigerant detection and mitigation verification by introduced signal"

+ - "Verification of drain pan drainage during cooling operation"

+ - "Integrated testing with the fire alarm system"

+ - "Trend review over a seasonal period"

+default:

+ - "Manufacturer startup with a signed report"

+ - "Point-to-point verification of every control device"

+ - "Functional performance testing of the control sequences"

+ - "Verified trip of every safety device at its setpoint"

+ - "Economizer changeover verification across the high-limit setpoint"

+ - "Verification of drain pan drainage during cooling operation"

+ - "Integrated testing with the fire alarm system"

+```

+### Commissioning shall be performed in accordance with [[sync/commissioning]].

+### Economizer fault detection shall be verified by inducing each fault class the controller is required to detect and confirming that the fault is reported on every selected reporting path.

+### Drain pan drainage shall be verified during cooling operation, with the coil condensing and the fan at design speed, by observing continuous flow at the drain and no accumulation in the pan.

+## Air Balancing {toc}

+### Testing, adjusting, and balancing shall be performed in accordance with [[sync/testing-adjusting-and-balancing]] after startup is complete and after the control sequences have been verified.

+### Measured supply airflow after balancing shall be within the tolerance indicated in the datasheet of the design value.

+```datasheet

+label: Airflow Balancing Tolerance

+type: range

+unit: '%'

+options:

+ min: 0

+ max: 15

+ step: 1

+default: 10

+```

+### Where the design airflow cannot be achieved within the tolerance, the balancing agent shall report the measured fan speed, static pressure, and motor current.

+### Where the design airflow cannot be achieved within the tolerance, the Engineer of Record shall determine the remedy.

+### Filters shall be clean at the time of the final balance.

+### The filter differential pressure shall be recorded at the time of the final balance.

+### The balance report shall record the as-left fan speed, drive component designations for belt drives, supply airflow, external static pressure, motor current, the minimum outdoor airflow, and the outdoor air damper minimum position.

+# Identification and Labeling {toc}

+## Each unit shall be furnished with a permanent nameplate on the exterior of the cabinet, mechanically fastened rather than adhered, of the material indicated in the datasheet.

+```datasheet

+label: Unit Nameplate Material

+type: select

+options:

+ - "Stainless steel"

+ - "Anodized aluminum"

+ - "Laminated phenolic"

+```

+## The nameplate shall state the unit tag, the manufacturer, the model and serial number, the nominal cooling capacity, the heating input or capacity, the design supply airflow, the refrigerant designation and factory charge by circuit, the electrical characteristics including minimum circuit ampacity and maximum overcurrent protective device, and the date of manufacture.

+## The unit tag on the nameplate shall match the tag used in the Contract Documents, on the building automation system, and in the operation and maintenance manuals.

+## Units charged with a refrigerant in a flammable safety group shall bear the flammable refrigerant marking UL 60335-2-40 and ASHRAE 15 require, applied at the location the listing designates.

+## The filter access panel shall be labeled with the filter efficiency and sizes the section holds.

+## The electrical compartment shall contain a permanently mounted copy of the unit wiring diagram.

+## Control terminal strips shall be labeled to match the submitted point list.

+# Warranty {toc}

+## Unit Warranty {toc}

+### The manufacturer shall warrant each unit against defects in materials and workmanship for the terms indicated in the datasheet.

+```datasheet

+label: Unit Parts Warranty Term

+type: range

+unit: years

+options:

+ min: 1

+ max: 10

+ setpoints: [1, 2, 3, 5, 10]

+default: 1

+```

+```datasheet

+label: Unit Labor Warranty Term

+type: range

+unit: years

+options:

+ min: 0

+ max: 5

+ setpoints: [0, 1, 2, 3, 5]

+default: 1

+```

+```datasheet

+label: Warranty Start Milestone

+type: radio

+options:

+ - "Date of substantial completion"

+ - "Date the Owner takes beneficial use of the system"

+ - "Date of shipment"

+default: "Date of substantial completion"

+```

+### Parts and labor are separate commitments commonly sold at different terms, which is why they are stated separately here. A parts-only extension transfers the cost of the component and leaves the Owner paying for the technician, the crane, and the refrigerant, so the two terms have to be read together to know what the coverage is worth on a rooftop. {note}

+### A component repaired or replaced under warranty shall carry a warranty for a full term from the date of the repair or for the remainder of the original term, whichever ends later.

+## Compressor Warranty {toc}

+### Each compressor shall be warranted against defects in materials and workmanship for the term indicated in the datasheet, in addition to the unit warranty.

+```datasheet

+label: Compressor Warranty Term

+type: range

+unit: years

+options:

+ min: 1

+ max: 10

+ setpoints: [1, 2, 3, 5, 10]

+default: 5

+```

+### The compressor warranty shall not be conditioned on service by the manufacturer's own organization where the service is performed by a technician certified under 40 CFR Part 82 Subpart F and, for a flammable refrigerant, trained for that refrigerant.

+## Gas Heat Exchanger Warranty {toc}

+### Requirements in this article apply where the datasheet selects a gas-fired heating source or a gas-fired supplemental heat source.

+### The gas heat exchanger shall be warranted against failure by cracking, burn-through, and corrosion for the term indicated in the datasheet, in addition to the unit warranty.

+```datasheet

+label: Gas Heat Exchanger Warranty Term

+type: range

+unit: years

+options:

+ min: 1

+ max: 25

+ setpoints: [1, 5, 10, 15, 20, 25]

+default: 10

+```

+### Where a heat exchanger warranty term is conditioned on the heat exchanger material, the term stated in the datasheet shall apply to the material selected in the datasheet.

+### Manufacturers commonly publish a longer heat exchanger term for a stainless heat exchanger than for an aluminized one, and the published term is often what settles the material choice on a project that would otherwise accept either. {note}

+## Warranty Service {toc}

+### The manufacturer shall maintain factory-trained service capability for the units furnished within the region of the project for the duration of the warranty term.

+### The manufacturer shall respond to a warranty notification within 2 business days.

+### The Contractor shall warrant the installation, including the curb setting, flashing, duct and utility connections, isolation, and condensate and control connections, for the term indicated in the datasheet.

+```datasheet

+label: Installation Warranty Term

+type: range

+unit: years

+options:

+ min: 1

+ max: 5

+ setpoints: [1, 2, 3, 5]

+default: 1

+```

+### A defect attributable to the installation shall be corrected at the Contractor's expense.

+### Where a warranty repair requires removal or modification of roofing or other adjacent work, the cost of removing and restoring that work shall be borne by the party responsible for the defect.

+### The manufacturer's warranty shall not be voided by a field refrigerant charge adjustment, a detection sensor replacement, or a filter or belt change performed in accordance with the operation and maintenance manual by a qualified technician.

+# Spare Parts {toc}

+## The Contractor shall furnish the spare parts indicated in the datasheet at substantial completion.

+```datasheet

+label: Spare Parts Furnished

+type: checkbox

+options:

+ - "One complete set of filters of every size installed"

+ - "Two complete sets of filters of every size installed"

+ - "One complete set of drive belts for every belt-driven fan"

+ - "One set of access panel and door gaskets for each unit"

+ - "One set of every fuse type installed"

+ - "One spare refrigerant detection sensor for each unit on which a detection system is furnished"

+ - "One spare economizer changeover sensor of each type installed"

+ - "One spare ignition control and flame sensor for each gas-fired heating section type installed"

+default:

+ - "One complete set of filters of every size installed"

+ - "One complete set of drive belts for every belt-driven fan"

+ - "One set of every fuse type installed"

+```

+## The Contractor shall obtain a signed receipt from the Owner for the spare parts delivered.

+## Spare parts shall be delivered in the manufacturer's packaging, labeled with the unit tag they serve and with the manufacturer's part designation.

+## Spare filters shall be stored in sealed packaging in a clean, dry location the Owner designates.

+## The Contractor shall furnish a written inventory correlating each spare item to the unit it serves and the location where it was stored.

+## The operation and maintenance manual shall include a filter change schedule derived from the initial and change-out resistances stated in the submittal, and, where a detection system is furnished, the replacement date of each refrigerant detection sensor.

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