−---
−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
−
−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. 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.
−
−A packaged rooftop unit is distinguished from a central station air handler by its integral, factory-charged refrigerant system: the compressors, condenser, and evaporator are contained within a single weatherproof cabinet, eliminating the field-installed chilled water plant and the associated hydronic piping. The unit rejects heat directly to outdoor air through its condenser and delivers conditioned supply air to the building through ductwork penetrating the roof curb. This packaging makes RTUs the dominant equipment type for low- and mid-rise commercial construction.
−
−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
−
−Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited. Where conflicts exist between referenced standards, 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 (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 |
−
−# Submittals
−
−## Action Submittals
−
−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
−
−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
−
−# Quality Assurance
−
−## Manufacturer Qualifications
−
−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 and the capability to provide replacement parts and factory-authorized service within the project region for a minimum of fifteen years after the date of manufacture.
−
−## AHRI Certification
−
−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.
−
−```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)"
−```
−
−## NRTL Listing
−
−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
−
−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
−
−RTUs shall be selected and rated for the operating conditions at the installation site. Design conditions are [[drawing: as indicated on the mechanical schedules]]. 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
−
−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.
−
−```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"
−```
−
−## Corrosive and Coastal Environments
−
−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.
−
−```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"
−```
−
−# Performance and Efficiency
−
−## Cooling Capacity
−
−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.
−
−```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
−```
−
−## Efficiency Ratings
−
−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. 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. 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.
−
−```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
−```
−
−# Refrigerant System
−
−## Refrigerant Selection
−
−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. R-454B and R-32 are the predominant replacements; both carry an ASHRAE 34 A2L (lower-toxicity, lower-flammability) classification and a global warming potential substantially below R-410A. Specifying R-410A on new units is no longer aligned with current production and should be limited to replacement components for existing equipment.
−
−```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"
−```
−
−## A2L Safety Provisions
−
−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.
−
−```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)"
−```
−
−## Compressor Type and Capacity Control
−
−Compressors shall be hermetic or semi-hermetic scroll type. 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. Variable-capacity compression delivers the highest part-load efficiency and the tightest temperature and humidity control but at higher first cost; staged compression is the common choice for most commercial applications. 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.
−
−```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)"
−```
−
−# Heating
−
−## Heating Source
−
−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. A hydronic heating coil allows the unit to be served by a building hot water plant where one exists.
−
−```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)"
−```
−
−## Gas-Fired Heating Section
−
−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.
−
−```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
−```
−
−## Electric and Heat Pump Heating
−
−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.
−
−```datasheet
−label: Electric / Supplemental Heat Capacity
−type: range
−unit: kW
−drawing_ref: true
−options:
− min: 5
− max: 150
− step: 5
−default: 30
−```
−
−# Economizer and Ventilation
−
−## Air-Side Economizer
−
−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. A low-leakage outdoor-air damper is essential: a leaky economizer damper admits unconditioned air during mechanical cooling and heating, wasting energy year-round.
−
−```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)"
−```
−
−Differential enthalpy control captures the most economizer hours in humid climates but requires enthalpy sensors that need periodic calibration. Fixed or differential dry-bulb control is simpler and more reliable in dry climates. The design team shall select the changeover strategy appropriate to the climate zone and the Owner's maintenance capability.
−
−## Economizer Fault Detection and Diagnostics
−
−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.
−
−```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)"
−```
−
−## Outdoor-Air Ventilation
−
−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.
−
−```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
−```
−
−## Demand-Controlled Ventilation
−
−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 reduces the energy penalty of ventilating for peak occupancy when a space is partly occupied, while maintaining ASHRAE 62.1 ventilation per person. DCV shall not reduce outdoor air below the area-based (base) ventilation rate required for the space.
−
−```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)"
−```
−
−# Supply Fan and Air Distribution
−
−## Supply Fan Type and Volume Control
−
−The supply fan moves conditioned air through the evaporator coil and the building ductwork against the design external static pressure. Constant-volume units use a fixed-speed fan and are appropriate for single-zone applications. VAV units 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 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.
−
−```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)"
−```
−
−## Design External Static Pressure and Fan Power
−
−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.
−
−```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"
−```
−
−# Cabinet and Construction
−
−## Cabinet Construction
−
−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. Double-wall construction prevents exterior sweating, protects the insulation from erosion and moisture, and improves cabinet rigidity and sound attenuation. Panels shall be insulated to limit thermal loss and surface condensation.
−
−```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)"
−```
−
−## Exterior Finish
−
−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.
−
−```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"
−```
−
−## Access Panels
−
−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.
−
−```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"
−```
−
−## Filtration
−
−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. 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. The fan selection shall account for the final (loaded) filter resistance.
−
−```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)"
−```
−
−## Condensate Drain Pan
−
−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.
−
−```datasheet
−label: Condensate Drain Pan Material
−type: radio
−options:
− - "Stainless steel"
− - "Corrosion-resistant coated steel"
− - "Molded composite / polymer"
−default: "Stainless steel"
−```
−
−# Roof Curb and Vibration Isolation
−
−## Roof Curb
−
−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]].
−
−```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
−```
−
−## Vibration Isolation
−
−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. For units over heavy structural slabs remote from occupancy, a standard curb with the unit's integral isolation is generally adequate.
−
−```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)"
−```
−
−## Seismic and Wind Restraint
−
−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]].
−
−```datasheet
−label: Seismic / Wind Restraint
−type: radio
−options:
− - "Required — per ASCE 7 and applicable building code"
− - "Not required"
−default: "Not required"
−```
−
−# Electrical
−
−## Power Connection
−
−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]].
−
−```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"
−```
−
−## Convenience and Service Provisions
−
−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.
−
−```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"
−```
−
−# Controls Integration
−
−## Unit Controller and BAS Interface
−
−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.
−
−```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)"
−```
−
−## Minimum Control Points
−
−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
−
−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.
−
−```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)"
−```
−
−# Factory Testing
−
−Every unit shall be factory run-tested before shipment. The refrigerant circuit(s) shall be evacuated, charged, and leak-tested; 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.
−
−```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"
−```
−
−# Installation and Startup
−
−## Rigging and Setting
−
−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.
−
−```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"
−```
−
−## Roofing, Flashing, and Penetrations
−
−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
−
−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
−
−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.
−
−```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)"
−```
−
−# Warranty
−
−## Equipment Warranty
−
−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.
−
−```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"
−```
−
−## Compressor Warranty
−
−Each compressor shall carry an extended warranty separate from the base equipment warranty.
−
−```datasheet
−label: Compressor Warranty
−type: radio
−options:
− - "1 year (same as equipment warranty)"
− - "5 years on compressor"
−default: "5 years on compressor"
−```
−
−## Heat Exchanger Warranty
−
−The gas-fired heat exchanger shall carry an extended warranty against thermal failure.
−
−```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"
−```
−
−## Installation Warranty
−
−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
−
−```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)"
−```
−
−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.
−
−# Identification and Labeling
−
−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.
−
−```datasheet
−label: Unit Nameplate Material
−type: radio
−options:
− - "Stainless steel — outdoor rooftop service"
− - "Anodized aluminum or laminated phenolic"
−default: "Stainless steel — outdoor rooftop service"
−```
+---
+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.