SynC™

SynC · Editorial revision

Air Terminal Units

Revision8
EditedAug 29, 2026
StatusCurrent
Contents

View changes in this revision   Revision history

Current revision. This is editorial revision 8, the current text of this standard. Read it on the standard's page.

SynC Standards Team — Specifier (Platform Standards) ✓ OfficialDiscloses employment SynC (SynC Platform Team)
Neutrality remake campaign: from-scratch field derivation per authoring cheatsheet; project parameters and derived dispositions

1 Scope

NOTE This standard covers the performance, construction, control, installation, and field verification of factory-fabricated air terminal units - the equipment at which a central air system is divided among individual thermal zones, and at which the air delivered to each zone is metered and, where the zone requires it, reheated or supplemented with induced plenum air. (1.1)
NOTE Equipment covered includes the unit casing and its acoustic treatment, the primary damper and its actuator, the primary airflow sensing element, hot water, steam, and electric reheat sections with their valves and safety devices, the fan section of a fan-powered unit, and the zone controller and zone sensor furnished with the unit. (1.2)
NOTE The terminal unit is the point at which system-level design intent becomes zone-level reality: its minimum airflow setting determines whether the zone receives the ventilation rate the system calculation assumed, its sound performance determines whether the space is usable for its program, and its reheat energy is consumed at every hour the zone is not at its cooling design load. (1.3)
NOTE The following are outside the scope of this standard: (1.4)
  • Diffusers, grilles, registers, and transfer openings at the room boundary, covered by HVAC Air Distribution DevicesHVAC Air Distribution DevicesResolves to the current adopted revision.sync/hvac-air-distribution-devices
  • Central station air handling units, rooftop units, and their fans, coils, and filter sections, covered by Air Handling UnitsAir Handling UnitsResolves to the current adopted revision.sync/air-handling-units
  • Duct construction, sealing, hangers, and leakage testing upstream and downstream of the unit, covered by HVAC DuctworkHVAC DuctworkResolves to the current adopted revision.sync/hvac-ductwork
  • Hot water and steam distribution piping, specialties, and the heating plant serving reheat coils, covered by Hydronic PipingHydronic PipingResolves to the current adopted revision.sync/hydronic-piping
  • Supervisory controllers, network infrastructure, graphics, trending, and system-level control sequences, covered by Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system
  • System-wide balancing procedure, instrumentation, and report format, covered by Testing Adjusting And BalancingTesting, Adjusting, and Balancing for HVACResolves to the current adopted revision.sync/testing-adjusting-and-balancing
  • Fan coil units, blower coil units, chilled beams, and induction units, whose primary function is conditioning recirculated room air rather than metering primary air
  • Venturi-style airflow control valves used for critical pressurization in laboratory, vivarium, and containment service
  • Underfloor air distribution plenum boxes and floor-mounted terminal units fed from a pressurized supply plenum
  • Standalone fire dampers, smoke dampers, and combination fire and smoke dampers furnished separately from the terminal unit
1.5 Airflow, capacity, pressure drop, and leakage performance cited for any unit under this standard shall be derived from testing in accordance with ANSI/ASHRAE 130 and rated in accordance with ANSI/AHRI 880.
1.6 Sound power cited for any unit under this standard shall be derived from testing in accordance with ANSI/ASHRAE 130 in a room qualified to ANSI/AHRI 220, and occupied-space sound levels shall be estimated in accordance with ANSI/AHRI 885.
1.7 Where a requirement of this standard conflicts with the equipment listing under which a unit is certified by a Nationally Recognized Testing Laboratory, the listing shall govern and the Contractor shall report the conflict to the Engineer of Record before fabrication.

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
Standard Title
ANSI/AHRI 880 Performance Rating of Air Terminals
ANSI/AHRI 885 Procedure for Estimating Occupied Space Sound Levels in the Application of Air Terminals and Air Outlets
ANSI/AHRI 220 Reverberation Room Qualification for Determining Sound Power of HVAC Equipment
ANSI/ASHRAE 130 Methods of Testing Air Terminal Units
ANSI/ASHRAE 62.1 Ventilation and Acceptable Indoor Air Quality
ANSI/ASHRAE/IES 90.1 Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings
ANSI/ASHRAE 111 Measurement, Testing, Adjusting, and Balancing of Building HVAC Systems
ANSI/ASHRAE 135 BACnet - A Data Communication Protocol for Building Automation and Control Networks
ANSI/ASHRAE 52.2 Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size
ANSI/ASHRAE 202 Commissioning Process for Buildings and Systems
ASHRAE Guideline 36 High-Performance Sequences of Operation for HVAC Systems
ANSI/ASA S12.2 Criteria for Evaluating Room Noise
NFPA 90A Standard for the Installation of Air-Conditioning and Ventilating Systems
NFPA 70 National Electrical Code, Article 424, Fixed Electric Space-Heating Equipment
UL 60335-2-40 Household and Similar Electrical Appliances - Particular Requirements for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers
UL 1995 Heating and Cooling Equipment
UL 1996 Electric Duct Heaters
UL 2043 Fire Test for Heat and Visible Smoke Release for Discrete Products and Their Accessories Installed in Air-Handling Spaces
UL 181 Factory-Made Air Ducts and Air Connectors
ASTM E84 Standard Test Method for Surface Burning Characteristics of Building Materials
ASTM C1071 Standard Specification for Fibrous Glass Duct Lining Insulation, Thermal and Sound Absorbing Material
ASTM C1338 Standard Test Method for Determining Fungi Resistance of Insulation Materials and Facings
ASTM A653 Standard Specification for Steel Sheet, Zinc-Coated or Zinc-Iron Alloy-Coated by the Hot-Dip Process
ASTM A240 Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip
ASTM B75 Standard Specification for Seamless Copper Tube
ANSI/AMCA 210 / ANSI/ASHRAE 51 Laboratory Methods of Testing Fans for Certified Aerodynamic Performance Rating
NEMA MG 1 Motors and Generators
SMACNA HVAC Duct Construction Standards HVAC Duct Construction Standards - Metal and Flexible

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for the Engineer of Record's review and return, and shall not release any terminal unit for fabrication until the submittal covering it has been reviewed and returned:
  • Unit schedule keyed to the mechanical drawings, listing for each tag the metering arrangement, fan section, inlet size, primary maximum and minimum airflow, available inlet static pressure, reheat capacity, electrical characteristics, controller address, and outlet configuration
  • Certified rating data for each unit configuration, identifying the rating standard and the certification program under which the data is published
  • Casing pressure drop and casing air leakage at the scheduled airflow and at the scheduled inlet static pressure
  • Radiated and discharge sound power in octave bands 2 through 7 at the scheduled primary airflow and inlet static pressure, with the occupied-space sound level for each scheduled zone and the room correction values used to produce it
  • Primary airflow sensor data giving the sensing element type, the measurement error as a percentage of reading across the scheduled airflow range, the low-flow threshold below which the published accuracy no longer applies, and the straight duct length required upstream and downstream of the inlet for rated accuracy
  • Primary damper data giving blade arrangement, blade and frame material, shaft and bearing type, seal material, close-off leakage at the rated differential pressure, and the maximum differential pressure against which the actuator will stroke the damper
  • Actuator data giving control signal type, fail-safe behavior, stroke time, and torque
  • Hot water or steam coil data giving row count, fin spacing, tube and fin material, working pressure rating, entering and leaving air and fluid conditions, capacity, and air-side and fluid-side pressure drop
  • Control valve and valve actuator data giving flow coefficient, close-off pressure rating, fail position, control signal type, and stroke time
  • Electric heater data giving element construction, capacity control method, stage count, capacity per stage, watt density, electrical characteristics, minimum airflow for heater operation, and the safety devices furnished
  • Fan section data giving wheel type, motor type, nameplate power, electrical characteristics, speed control means, airflow and static pressure at the design operating point, and the induced-air opening arrangement
  • Controller data giving the network protocol, the hardwired point count by type, the control sequences the controller executes, and the fire performance listing for products installed in air-handling spaces
  • Casing liner and attenuator data giving liner type, thickness, airstream facing, surface burning characteristics, fungal resistance, and the maximum airstream velocity at which the facing is rated against erosion
  • Shop drawings showing each unit in plan and section with every field connection point dimensioned, the required service clearance, the access panel locations, and the operating weight
  • Evidence of the Nationally Recognized Testing Laboratory listing for each unit configuration containing an electric heater, a fan motor, or an electrically powered control
Action Submittals Requiredcheckbox
☑ Unit schedule keyed to the mechanical drawings
☑ Certified rating data for each unit configuration
☑ Casing pressure drop and casing air leakage data
☑ Radiated and discharge sound data with occupied-space levels
☑ Primary airflow sensor accuracy and straight duct requirements
☑ Primary damper data with close-off leakage
☑ Actuator data with signal type, fail behavior, and stroke time
☐ Hot water or steam coil selection data
☐ Control valve and valve actuator data
☐ Electric heater data with safety devices
☐ Fan section data for fan-powered units
☑ Controller data with protocol and point count
☑ Casing liner and attenuator construction data
☑ Shop drawings with clearances and field connections
☑ Nationally Recognized Testing Laboratory listing evidence
3.1.2 Where the Contractor proposes a unit from a manufacturer other than the one on which the design was based, the submittal shall include a side-by-side comparison of radiated sound, discharge sound, casing pressure drop, and airflow sensor low-flow threshold at the scheduled airflow for the proposed and the scheduled unit.
3.1.3 Where the Contractor proposes a substitution that changes the inlet size, the casing dimensions, or the required service clearance of any unit, the submittal shall identify every duct, pipe, and ceiling coordination item affected.

3.2 Closeout Submittals

3.2.1 Before final acceptance of the air distribution system, the Contractor shall submit the following:
  • Operation and maintenance manuals covering installation, operation, maintenance, and troubleshooting, with the recommended preventive maintenance interval for each serviceable component
  • As-built unit schedule recording every field substitution and every field modification to the submitted configuration, together with the review documentation for each
  • Factory test record for each unit, including the airflow sensor calibration constant established at the factory
  • Field commissioning record for each unit, giving the measured airflow at every commanded setpoint, the reheat stroke or stage verification, and the point-by-point verification of the controller interface
  • Controller parameter file for each unit in the manufacturer's native format, listing the as-commissioned setpoints, calibration constants, and control loop tuning values
  • Warranty documentation from the terminal unit manufacturer and from each separately warranted component supplier
Closeout Submittals Requiredcheckbox
☑ Operation and maintenance manuals
☑ As-built unit schedule with field modifications
☑ Factory test record for each unit
☑ Field commissioning record for each unit
☑ Controller parameter file in native format
☑ Warranty documentation
NOTE The controller parameter file is the only complete record of what the units were actually commissioned to do, and it is the difference between a rebalancing effort that starts from the as-left condition and one that starts from scratch. (3.2.2)

4 Quality Assurance

4.1 Manufacturer Qualifications

4.1.1 Terminal units shall be produced by a manufacturer that has continuously produced factory-fabricated air terminal units for commercial service for not less than five years.
4.1.2 The manufacturer shall publish a catalog covering the full range of units supplied to the project, including rated performance at each cataloged inlet size.
4.1.3 The manufacturer shall maintain replacement dampers, actuators, airflow sensors, coils, motors, and controllers for the units supplied for not less than ten years after the date of Substantial Completion.
4.1.4 All terminal units on the project shall be furnished by a single manufacturer so that the control interface, the service access pattern, and the spare parts inventory are common across the installation.
4.1.5 Where the Contract Documents divide the project into separately bid phases or buildings, the single-manufacturer requirement applies within each phase or building rather than across the project.

4.2 Basis of Published Performance Data

4.2.1 The basis on which the performance of each unit configuration is established shall be as indicated in the datasheet.
Basis of Certified Performance Ratingsradio
● AHRI 880 certified ratings for every unit configuration furnished
○ AHRI 880 certified ratings, with independent laboratory test data to ANSI/ASHRAE 130 accepted for a configuration outside the certified range
○ Independent laboratory test data to ANSI/ASHRAE 130 for every unit configuration furnished
4.2.2 The certification mark or the independent laboratory test report reference, as applicable to the basis selected, shall appear on the product data submitted for each unit configuration.
NOTE A certification program covers a defined range of sizes and configurations, and a manufacturer that participates in the program may still catalog a unit outside that range. The distinction matters because ratings inside the range are verified by a third party on a sampling basis, while ratings outside it rest on the manufacturer's own test data. (4.2.3)
4.2.4 Where the parties disagree whether a proposed unit configuration falls within the certified range, the Engineer of Record shall make the initial determination.

4.3 Product Listing and Labeling

4.3.1 Terminal units containing an electric heater, a fan motor, or an electrically powered control shall be listed and labeled by a Nationally Recognized Testing Laboratory to UL 60335-2-40, to UL 1995 where the Authority Having Jurisdiction accepts that listing, or to UL 1996 where the heater section is listed as a duct heater.
4.3.2 Electric heater sections shall comply with NFPA 70 Article 424.
4.3.3 Products installed in a ceiling plenum or other air-handling space used to convey environmental air shall comply with the heat and smoke release limits of UL 2043 or shall be enclosed in a manner that NFPA 90A accepts for that space.
4.3.4 The listing label shall be affixed to the casing exterior in a location that remains visible after installation.

4.4 Pre-Installation Conference

4.4.1 Before installation of terminal units begins, the Contractor shall convene a pre-installation conference attended by the mechanical, controls, and electrical subcontractors, the testing and balancing agent, and the commissioning authority where one is engaged.
4.4.2 The pre-installation conference agenda shall include service clearance and access panel coordination, the straight duct length required at each unit inlet, the sequence in which duct, pipe, power, and control connections are made, controller addressing against the unit tag schedule, and the schedule for airflow verification and point checkout.
NOTE The straight duct length at the inlet is the item most often lost between shop drawing coordination and installation, because it competes for the same overhead space as every other trade and it is the only one of them whose loss is invisible until the unit will not hold its airflow setpoint. (4.4.3)

5 Service Environment

5.1 Terminal unit locations, tags, and orientations are as indicated on the mechanical plans.
5.2 The ceiling or enclosure construction below each terminal unit is as indicated on the reflected ceiling plan.
5.3 Terminal units shall be suitable for continuous operation at an ambient dry-bulb temperature from 50 °F to 104 °F and at a relative humidity from 10% to 90% without condensation on any surface of the casing or the controller enclosure.
5.4 Terminal units are not weather-resistant as manufactured, and shall not be installed outdoors or in any location exposed to precipitation, wind-driven moisture, or freezing temperatures unless the manufacturer certifies the unit for that exposure in writing.
5.5 Where a unit is installed in a space whose ambient conditions fall outside the range stated above, the Contractor shall obtain the manufacturer's written confirmation of suitability, together with any required change to the casing, the controller enclosure, or the condensate provisions, before the unit is released for fabrication.
5.6 The controller and actuator enclosure rating shall be as indicated in the datasheet.
Controller and Actuator Enclosure Ratingselect
NEMA 1, general purpose
NEMA 1 with a gasketed cover
NEMA 3R, rain resistant
NEMA 4, watertight
NEMA 4X, watertight and corrosion resistant
5.7 The exterior casing insulation provided for condensation control shall be as indicated in the datasheet.
Exterior Casing Insulation for Condensation Controlradio
● No exterior insulation
○ Factory-applied exterior insulation with a vapor retarder
○ Field-applied exterior insulation with a vapor retarder
NOTE A unit metering cold primary air through a plenum whose dew point exceeds the primary air temperature will condense on the casing, and the water reaches the ceiling tile below before anything is visible from the space. The exposure is set by the plenum, not by the unit, so it has to be evaluated for the actual return path rather than assumed from the building type. (5.8)
5.9 Where the ceiling plenum is unconditioned, is open to outdoor air, or has a design dew point above the design primary air temperature, terminal unit casings shall be insulated on the exterior and the insulation shall be continuous and sealed at every penetration and connection.

6 Terminal Unit Configuration

6.2 Primary Air Metering Arrangement

6.2.1 The primary air metering arrangement shall be as indicated in the datasheet.
Primary Air Metering Arrangementselect
Single-duct
Dual-duct mixing
Bypass, diverting excess primary air to the return path
NOTE A single-duct unit meters one primary airstream from a central system that delivers air at a single temperature, and it is the arrangement most central variable-volume systems are built around. (6.2.2)
NOTE A dual-duct unit accepts separate cold and warm primary airstreams and proportions the mixture delivered to the zone, which lets a zone be heated without a local heat source at the cost of running two duct systems to every unit. (6.2.3)
NOTE A bypass unit passes a fixed total airflow and diverts the portion the zone does not need into the return path, which lets a constant-volume central unit serve multiple zones without a variable-speed fan. The diverted air is conditioned but does no work, so the central fan energy does not fall as the zones unload. (6.2.4)
6.2.5 The bypass path of a bypass unit shall discharge into a return plenum or a ducted return that returns to the same central unit, and shall not discharge into an occupied space.

6.3 Fan Section Arrangement

6.3.1 The fan section arrangement shall be as indicated in the datasheet.
Fan Section Arrangementradio
● No fan section
○ Parallel arrangement, fan intermittent and offset from the primary airstream
○ Series arrangement, fan continuous and in line with the primary airstream
NOTE In a parallel arrangement the fan sits beside the primary airstream and runs only when the zone calls for heating or when the unit is in an unoccupied mode, so the fan consumes no energy through the cooling hours that dominate most operating schedules. (6.3.2)
NOTE In a series arrangement the fan sits in the primary airstream and runs whenever the zone is occupied, so the zone receives a constant total airflow and a constant outlet velocity regardless of how far the primary damper has closed. (6.3.3)
NOTE Where diffuser performance at low airflow governs comfort, or where the zone requires a constant discharge velocity, the constant total airflow of a series arrangement holds outlet conditions steady at part load that a single-duct unit cannot. Where fan energy over the full operating schedule governs, the intermittent fan of a parallel arrangement runs for a small fraction of the hours a series fan runs. (6.3.4)
6.3.5 Where a fan section is selected, the induced-air opening shall draw from the ceiling return plenum or from a ducted return, and shall not draw from an unconditioned space, a shaft, or a space subject to contaminant migration.

6.4 Primary Airflow Control Mode

6.4.1 The primary airflow control mode shall be as indicated in the datasheet.
Primary Airflow Control Moderadio
● Variable air volume
○ Constant volume
NOTE A constant-volume unit holds a fixed airflow setpoint and controls zone temperature entirely by reheat, which suits spaces whose ventilation or pressurization requirement is fixed by function rather than by load. Every Btu of cooling delivered above the zone's need is then paid for twice, once at the central coil and once at the reheat coil. (6.4.2)

6.5 Primary Airflow Control Basis

6.5.1 The primary airflow control basis shall be as indicated in the datasheet.
Primary Airflow Control Basisradio
● Pressure independent, closed-loop control on a measured primary airflow signal
○ Pressure dependent, damper position commanded directly from the zone temperature loop
NOTE A pressure-independent unit measures its own primary airflow and drives the damper to hold the commanded setpoint, so the airflow it delivers is the airflow the ventilation calculation assumed no matter what the upstream static pressure is doing. (6.5.2)
NOTE A pressure-dependent unit has no airflow feedback, so its delivered airflow rises and falls with system static pressure and cannot be relied upon to hold a minimum ventilation rate as other zones open and close. Where a project's ventilation compliance path depends on a known minimum airflow at every zone, a pressure-dependent unit cannot supply the evidence. (6.5.3)
6.5.4 Where pressure-dependent control is selected, the Engineer of Record shall document how the zone's minimum outdoor air rate under ANSI/ASHRAE 62.1 is maintained across the range of system static pressures the unit will see.

6.6 Dual-Duct Mixing Section

6.6.1 Requirements in this article apply where a dual-duct metering arrangement is selected in the datasheet.
6.6.2 The dual-duct mixing section shall be as indicated in the datasheet.
Dual-Duct Mixing Sectionradio
○ Common outlet with no internal mixing section
○ Internal mixing attenuator ahead of the outlet
6.6.3 Where a dual-duct metering arrangement is selected, each inlet shall be furnished with its own damper, its own actuator, and its own airflow sensing element.
NOTE Cold and warm air entering a common outlet without a mixing section leave the unit in stratified layers that persist for several duct diameters, so a discharge temperature sensor placed close to the outlet reads the layer it happens to sit in rather than the mixed temperature the zone receives. (6.6.4)
6.6.5 Where a discharge air temperature sensor is provided on a dual-duct unit with no internal mixing section, it shall be located downstream of the mixing distance the manufacturer publishes for the unit.

7 Primary Airflow and Inlet Sizing

7.1 Inlet Size

7.1.1 The primary inlet nominal size shall be as indicated in the datasheet.
Primary Inlet Nominal Diameterrange
in.
456789101214162024
Per drawings — inlet size as indicated on the terminal unit schedule (deferred by default)
7.1.2 Where a unit is cataloged with a rectangular primary inlet rather than a round inlet, the inlet shall be sized for an equivalent free area not less than that of the scheduled nominal diameter, and the shop drawing shall dimension the rectangular inlet.
7.1.3 The inlet size shall be selected so that the scheduled primary maximum airflow falls within the certified flow range of the unit and the scheduled primary minimum airflow falls above the low-flow threshold published for the airflow sensing element at that inlet size.
NOTE Inlet size is the single selection that most often decides whether a terminal unit performs. Sized too small, the unit consumes inlet static pressure the system does not have and generates sound at the damper that no downstream treatment removes. Sized too large, the velocity at the sensing element at minimum airflow falls below the threshold at which the published accuracy applies, and the zone's minimum ventilation rate becomes a number on a graphic rather than a measured quantity. (7.1.4)
7.1.5 The manufacturer shall state, for each scheduled unit, the low-flow threshold of the airflow sensing element at the selected inlet size in the same units as the scheduled minimum airflow.

7.2 Scheduled Airflow Setpoints

7.2.1 The primary maximum airflow shall be as indicated in the datasheet.
Primary Maximum Airflowrange
cfm
258000
Per drawings — airflow as indicated on the terminal unit schedule (deferred by default)
7.2.2 The primary minimum airflow in cooling shall be as indicated in the datasheet.
Primary Minimum Airflow in Coolingrange
cfm
08000
Per drawings — airflow as indicated on the terminal unit schedule (deferred by default)
7.2.3 The primary minimum airflow in heating shall be as indicated in the datasheet.
Primary Minimum Airflow in Heatingrange
cfm
08000
Per drawings — airflow as indicated on the terminal unit schedule (deferred by default)
7.2.4 The Engineer of Record shall determine the controlling minimum airflow for each zone as the largest of the zone outdoor air rate required by ANSI/ASHRAE 62.1 adjusted for system ventilation efficiency, the airflow required to deliver the design heating capacity, the reheat airflow limit of ANSI/ASHRAE/IES 90.1 applicable to the zone, and any stratification or acoustic floor the design establishes.
NOTE Setting the heating minimum equal to the cooling minimum is the most common origin of the complaint that a zone is cold while its box is calling for full heat. At the cooling minimum the reheat coil cannot raise the discharge temperature far enough above room temperature to overcome the buoyancy of the jet, so the warm air stays at the ceiling and the occupied zone is served by whatever room air the jet entrains. (7.2.5)
NOTE Where a fan section is provided, the fan adds induced plenum air to the primary air at the diffuser, so the discharge airflow in heating is set by the fan rather than by the primary minimum, and the primary minimum in heating can be set independently of the cold-air-dump consideration. (7.2.6)

7.3 Zone Airflow Control Logic

7.3.1 The zone airflow control logic shall be as indicated in the datasheet.
Zone Airflow Control Logicradio
○ Single maximum, one primary airflow maximum governing in both heating and cooling
○ Dual maximum, a separate cooling maximum and heating maximum with a discharge temperature reset band between them
NOTE Under single-maximum logic the unit holds one minimum through the deadband and the heating range, so the reheat coil works against the full minimum airflow whenever the zone calls for heat. (7.3.2)
NOTE Under dual-maximum logic the unit drops to a low minimum through the deadband, raises the discharge temperature before it raises airflow, and only then increases airflow toward a separate heating maximum, which reduces both the simultaneous heating and cooling energy and the airflow the central fan must deliver at part load. (7.3.3)
7.3.4 Where dual-maximum logic is selected, the terminal unit shall be furnished with a discharge air temperature sensor and the controller shall be capable of resetting discharge temperature independently of primary airflow.

7.4 Inlet Static Pressure and Casing Pressure Drop

7.4.1 The available inlet static pressure at the primary maximum airflow shall be as indicated in the datasheet.
Available Inlet Static Pressure at Primary Maximum Airflowrange
in. w.g.
0.056
Per drawings — inlet static pressure as indicated on the terminal unit schedule (deferred by default)
7.4.2 The maximum casing pressure drop at the primary maximum airflow shall be as indicated in the datasheet.
Maximum Casing Pressure Drop at Primary Maximum Airflowrange
in. w.g.
0.050.10.150.20.250.30.40.50.751
7.4.3 Each unit shall maintain the commanded primary airflow within the specified measurement accuracy from the available inlet static pressure indicated in the datasheet down to the minimum operating differential pressure the manufacturer publishes for the unit.
7.4.4 The manufacturer shall state the minimum operating differential pressure for each scheduled unit in the action submittal.
7.4.5 The Engineer of Record shall calculate the available inlet static pressure for the most hydraulically remote unit on each branch and shall size the central fan and the terminal units against that value.
NOTE Selecting terminal units against the central fan discharge static pressure rather than against the static pressure remaining at the unit inlet after the upstream duct losses produces units that appear adequate on paper and starve at the end of the run. (7.4.6)
NOTE Inlet static pressure above the value at which a unit is rated raises both radiated and discharge sound, so the central system static pressure control strategy and the terminal unit sound selection are the same decision viewed from two ends of the duct. Static pressure reset driven by damper position holds the inlet static near the minimum the most-open zone needs, which lowers sound at every hour the system is not at design. (7.4.7)
7.4.8 The central system static pressure control strategy shall be coordinated with Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system.

8 Casing Construction

8.1 Casing Material and Thickness

8.1.1 The casing material shall be as indicated in the datasheet.
Casing Materialselect
Galvanized steel sheet to ASTM A653 with G60 coating
Galvanized steel sheet to ASTM A653 with G90 coating
Aluminized steel sheet
Type 304 stainless steel sheet to ASTM A240
Type 316 stainless steel sheet to ASTM A240
8.1.2 The casing wrapper thickness shall be as indicated in the datasheet.
Casing Wrapper Thicknessselect
22 gauge
20 gauge
18 gauge
8.1.3 Inlet collars, outlet flanges, and any surface that receives a hanger or a duct connection shall be not lighter than 20 gauge.
8.1.4 Casings shall be of welded, riveted, or interlocked-seam construction, and every joint shall be sealed so that the assembled casing meets the specified leakage limit.
8.1.5 Seams closed only with adhesive tape shall not be used, because the tape adhesive fails at the elevated plenum temperatures and sustained pressure differentials the casing sees over its service life.

8.2 Casing Air Leakage

8.2.1 The maximum casing air leakage shall be as indicated in the datasheet, expressed as a percentage of the nominal cataloged primary airflow for the unit and measured at 1 in. w.g. internal static pressure.
Maximum Casing Air Leakage at 1 in. w.g.range
%
0.51235
NOTE Air that leaks out of the casing has been conditioned by the central system and metered by the unit, but it never reaches the zone. It is therefore subtracted twice: once from the airflow the zone actually receives and once from the ventilation the system-level calculation credited to that zone. (8.2.2)

8.3 Casing Liner and Attenuation

8.3.1 The casing liner type shall be as indicated in the datasheet.
Casing Liner Typeselect
Fibrous glass liner to ASTM C1071 with a coated or foil-faced airstream surface
Fibrous glass liner to ASTM C1071 with a perforated metal facing on the airstream side
Closed-cell elastomeric foam liner with no exposed fiber
Double-wall construction with fibrous glass encapsulated between solid metal skins
Double-wall construction with fibrous glass encapsulated behind a perforated inner skin
Unlined single-wall casing
8.3.2 The casing liner thickness shall be as indicated in the datasheet.
Casing Liner Thicknessrange
in.
0.511.52
NOTE The liner is the unit's only broadband attenuator, and it works on the damper noise generated a few inches upstream of it. Attenuation rises with thickness, most strongly in the mid and upper octave bands that govern the perceived level, while the added thickness reduces the free area of the casing and raises the velocity through it. (8.3.3)
NOTE Where a fiber-free airstream is required by the project program, by an infection control risk assessment, or by the process the space serves, a closed-cell liner or a double-wall construction with the fiber fully encapsulated provides the acoustic treatment without an exposed fibrous surface. (8.3.4)
8.3.5 Unless the datasheet selects an unlined casing, every unit shall be furnished with acoustic treatment complying with this article.
8.3.6 Liner materials and adhesives shall have a flame spread index not greater than 25 and a smoke developed index not greater than 50 when tested to ASTM E84.
8.3.7 Fibrous glass liner shall comply with ASTM C1071 and shall show no fungal growth when tested to ASTM C1338.
8.3.8 Liner airstream surfaces shall be coated, encapsulated, or faced so that no fiber erodes into the airstream at the maximum face velocity for which the unit is cataloged, and the manufacturer shall state that velocity in the action submittal.
8.3.9 Liner shall be secured mechanically as well as adhesively at every edge exposed to the airstream, and every cut edge shall be sealed.
8.3.10 Liner constructions carrying a UL 181 listing may be identified as such in the submittal, and the listing shall not be used in place of the surface burning and erosion requirements of this article.

8.4 Hanger, Mounting, and Access Provisions

8.4.1 Casings shall be furnished with integral mounting brackets, hanger lugs, or threaded inserts sized for the operating weight of the unit.
8.4.2 The Contractor shall not penetrate the casing to attach a hanger, because a field penetration breaches the liner, creates a leak path, and voids the leakage rating the unit was certified to.
8.4.3 Each unit shall be furnished with a removable access panel giving service access to the damper actuator, the airflow sensing element, the controller, the reheat section, and the fan and motor where present.
8.4.4 The access panel arrangement shall be as indicated in the datasheet.
Access Panel Arrangementradio
● Bottom access
○ Side access
○ Bottom and side access
8.4.5 Access panels shall be removable and replaceable without disturbing the duct connections, the piping connections, or the electrical connections at the unit.
8.4.6 Access panel fasteners shall be captive or shall be furnished in a quantity that permits replacement, and loose fasteners shall not be relied upon to maintain the casing leakage rating.

9 Primary Damper Assembly

9.1 Damper Construction

9.1.1 The primary damper blade arrangement shall be as indicated in the datasheet.
Primary Damper Blade Arrangementselect
Single blade in a round inlet
Opposed multiple blades in a rectangular inlet
Parallel multiple blades in a rectangular inlet
9.1.2 The damper blade and frame material shall be as indicated in the datasheet.
Damper Blade and Frame Materialradio
● Galvanized steel
○ Aluminum
○ Type 304 stainless steel
○ Type 316 stainless steel
9.1.3 The damper shaft bearing type shall be as indicated in the datasheet.
Damper Shaft Bearing Typeradio
○ Self-lubricating synthetic bushings
○ Oil-impregnated sintered bronze bearings
○ Sealed ball bearings
Manufacturer's standard (by default)
NOTE Bearings on a terminal damper carry almost no load and turn slowly, so the property that decides service life is resistance to seizing after long periods at a fixed position rather than load rating. Manufacturers meet that requirement with different bearing constructions across their product lines. (9.1.4)
9.1.5 The manufacturer shall state the bearing construction supplied for each scheduled unit in the action submittal.
9.1.6 The damper shaft shall be continuous through the casing and shall be indexed or marked so that the blade position is visible from outside the casing without removing an access panel.
9.1.7 Damper blades shall be stiffened as required to stroke without binding and without permanent deflection at the maximum differential pressure for which the unit is rated.
9.1.8 Damper shaft penetrations through the casing shall be sealed so that leakage past the penetration is included within the casing leakage limit at the rated differential pressure.

9.2 Damper Close-Off Leakage

9.2.1 The maximum damper close-off leakage shall be as indicated in the datasheet, expressed as a percentage of the nominal cataloged primary airflow for the unit and measured at 3 in. w.g. inlet static pressure with the damper commanded closed and the outlet open.
Maximum Damper Close-Off Leakage at 3 in. w.g.range
%
0.51235
NOTE Close-off leakage is what the zone receives when the control system believes it is delivering nothing. Where a sequence relies on a true zero-flow condition - unoccupied setback, a zone isolated for pressurization, a space shut down for a process - the leakage rate is the floor beneath which the sequence cannot go, and the tighter close-off is bought with a heavier blade, a positive seal, and more actuator torque. (9.2.2)
9.2.3 Where a zone control sequence commands a zero-airflow condition, the unit serving that zone shall be furnished with a damper seal rated for the close-off leakage indicated in the datasheet at the maximum inlet static pressure the branch can develop.

9.3 Damper Actuator

9.3.1 The damper actuator control signal shall be as indicated in the datasheet.
Damper Actuator Control Signalselect
Analog modulating, 0–10 VDC
Analog modulating, 4–20 mA
Floating point, three-wire tri-state
Pulse-width modulated
Pneumatic modulating, 3–15 psig
Two-position, line or low voltage
9.3.2 The damper actuator fail-safe behavior shall be as indicated in the datasheet.
Damper Actuator Fail-Safe Behaviorradio
● Non-spring-return, holding last position on loss of control signal or power
○ Spring-return to the closed position
○ Spring-return to the open position
9.3.3 The damper actuator stroke time shall be as indicated in the datasheet.
Damper Actuator Stroke Timerange
seconds
1530456090120180300
9.3.4 Actuators shall be direct-coupled to the damper shaft without a linkage, and shall be secured so that the coupling cannot slip on the shaft over the rated cycle life.
9.3.5 Where a spring-return fail-safe behavior is selected, the actuator shall drive the damper to the selected position on loss of control signal and on loss of power, and the position shall be reached within the stroke time indicated in the datasheet.
NOTE A stroke time far shorter than the airflow control loop's response time causes the loop to overshoot and hunt, because the damper reaches its commanded position before the sensor has registered the effect of the previous move. A stroke time far longer than the loop's response time leaves the zone unable to follow a load change. The two have to be matched, and the match is a property of the controller and the sensor as much as of the actuator. (9.3.6)
9.3.7 The Contractor shall verify that the actuator torque rating exceeds the damper torque required at the maximum inlet static pressure the branch can develop, including the torque required to compress a damper seal where one is provided.

10 Primary Airflow Sensing

10.1 Sensing Element

10.1.1 The primary airflow sensing element type shall be as indicated in the datasheet.
Primary Airflow Sensing Element Typeselect
Multi-point center-averaging differential pressure element
Single-point differential pressure element
Thermal dispersion sensing element
10.1.2 The sensing element shall be integral to the inlet collar, factory-installed, and factory-calibrated against a reference flow station for the specific unit it serves.
NOTE A multi-point element averages the pressure signal across the inlet cross-section, so a velocity profile that is not uniform still produces a representative average. A single-point element reads the profile at one location and therefore depends more heavily on the approach condition, while a thermal dispersion element reads velocity directly and holds usable resolution to a lower velocity than a differential pressure element of the same inlet size. (10.1.3)
10.1.4 The maximum primary airflow measurement error shall be as indicated in the datasheet, expressed as a percentage of reading over the scheduled airflow range.
Maximum Primary Airflow Measurement Errorrange
%
12351015
10.1.5 The manufacturer shall state the low-flow threshold below which the specified measurement error no longer applies, for each scheduled unit at its selected inlet size.
NOTE An accuracy stated as a percentage of reading holds proportionally across the range, while an accuracy stated as a percentage of full scale becomes a larger and larger fraction of the reading as airflow falls. At a minimum airflow that is a fifth of the maximum, the two conventions differ by a factor of five in the quantity that governs minimum ventilation. (10.1.6)

10.2 Approach Duct Condition

10.2.1 The minimum straight duct length upstream of the unit inlet shall be as indicated in the datasheet, expressed in inlet diameters.
Minimum Straight Duct Upstream of the Inletrange
inlet diameters
11.5235
10.2.2 Where the datasheet does not indicate a straight duct length, the length published by the sensing element manufacturer for rated accuracy at the selected inlet size shall govern, and the manufacturer shall state that length in the action submittal.
NOTE An elbow, tee, transition, or partly closed damper within the approach length skews the velocity profile at the inlet, and the sensing element reports the skewed average as though it were the true airflow. The unit then controls precisely to a wrong number, which is why the symptom appears at commissioning as a zone that balances only after its calibration constant is overridden. (10.2.3)
10.2.4 Where the required straight duct length cannot be provided at a unit, the Contractor shall report the condition to the Engineer of Record during shop drawing coordination rather than after installation.
10.2.5 Where the Engineer of Record accepts an installation with less than the required straight duct length, the calibration constant for that unit shall be established in the field against a calibrated reference instrument and shall be recorded in the closeout record.

11 Reheat

11.1 Reheat Medium

11.1.1 The reheat medium shall be as indicated in the datasheet.
Reheat Mediumselect
None
Hot water coil
Steam coil
Electric resistance
NOTE The reheat medium available to a project is set by the plant the project builds or already has, and by what the local energy code permits for new electric resistance heating in the building type and climate zone. Hot water offers high turndown and quiet operation at the cost of piping every zone; electric resistance eliminates the piping and the freeze exposure at the cost of a demand-coincident electrical load; steam suits an existing central steam plant and brings condensate return and trap maintenance to every zone. (11.1.2)
11.1.3 The Engineer of Record shall confirm that the selected reheat medium complies with the limits ANSI/ASHRAE/IES 90.1 and the adopted energy code place on new electric resistance heating for the building type and climate zone before the medium is released for fabrication.
11.1.4 Where no reheat is selected for a unit, the zone shall be served by a heat source outside this standard or shall be documented as requiring no heating.

11.2 Hot Water Reheat Coil

11.2.1 Requirements in this article apply where a hot water reheat coil is selected in the datasheet.
11.2.2 The reheat coil capacity shall be as indicated in the datasheet.
Reheat Coil Capacityrange
MBH
1150
Per drawings — coil capacity as indicated on the terminal unit schedule (deferred by default)
11.2.3 The reheat coil row count shall be as indicated in the datasheet.
Reheat Coil Row Countrange
rows
1234
Per drawings — coil rows as indicated on the terminal unit schedule (deferred by default)
11.2.4 The design hot water entering temperature shall be as indicated in the datasheet.
Hot Water Entering Temperaturerange
°F
100200
Per drawings — design fluid temperatures as indicated on the mechanical schedules (deferred by default)
11.2.5 The design hot water leaving temperature shall be as indicated in the datasheet.
Hot Water Leaving Temperaturerange
°F
80190
Per drawings — design fluid temperatures as indicated on the mechanical schedules (deferred by default)
NOTE Coil capacity falls steeply with entering water temperature, so a row count that satisfies a scheduled capacity on a 180 °F plant can fall short of the same capacity on a 140 °F plant by a margin no field adjustment recovers. Plants designed for condensing boilers or for heat pump heat recovery operate at the lower end of the range, which is why the row count has to be selected against the project's own scheduled water temperature rather than against a catalog reference condition. (11.2.6)
11.2.7 The coil tube material shall be as indicated in the datasheet.
Reheat Coil Tube Materialradio
● Seamless copper tube to ASTM B75
○ Type 304 stainless steel tube
○ Type 316 stainless steel tube
11.2.8 The coil fin material shall be as indicated in the datasheet.
Reheat Coil Fin Materialradio
● Aluminum plate fin
○ Copper plate fin
11.2.9 The coil working pressure rating shall be as indicated in the datasheet.
Reheat Coil Working Pressure Ratingrange
psig
100150200250300400
11.2.10 Fins shall be mechanically expanded onto the tubes to form a continuous metal-to-metal bond over the full finned length.
11.2.11 Coils shall be leak tested at the factory at not less than 1.5 times the specified working pressure rating and shall be shipped with the connections capped.
11.2.12 Coil connections shall extend beyond the casing far enough for the piping specialties required at the unit to be installed without cutting or modifying the casing.

11.3 Hot Water Reheat Control Valve

11.3.1 Requirements in this article apply to the control valve serving a hot water reheat coil selected in the datasheet.
11.3.2 The reheat control valve shall be as indicated in the datasheet.
Hot Water Reheat Control Valveselect
Pressure-independent control valve with a modulating actuator
Two-way modulating globe valve
Two-way modulating characterized ball valve
Three-way modulating valve
Two-position two-way valve
NOTE A pressure-independent valve holds the commanded flow regardless of the differential pressure across it, so a zone's flow does not shift as other zones on the same distribution modulate. A conventional two-way valve delivers the flow its authority and the local differential pressure produce, which is stable where the plant controls differential pressure closely and drifts where it does not. (11.3.3)
NOTE A three-way valve maintains flow through the distribution when the coil is not calling, which suits a constant-flow arrangement and defeats the flow reduction a variable-flow distribution is built to achieve. (11.3.4)
NOTE A two-position valve delivers full coil capacity or none, so the zone temperature cycles about the setpoint at an amplitude set by the coil capacity and the zone's thermal mass. (11.3.5)
11.3.6 The reheat control valve actuator fail position shall be as indicated in the datasheet.
Reheat Control Valve Actuator Fail Positionradio
○ Fail to the open position
○ Fail to the closed position
○ Fail in the last position
11.3.7 Where a unit serves a zone with an exterior exposure in a climate that reaches freezing temperatures, the reheat control valve shall fail to the open position so that a loss of control power does not leave a glazed zone without heat.
11.3.8 Where a unit serves a zone with no freeze exposure, the reheat control valve may fail to the closed position so that a loss of control power does not overheat the zone.
11.3.9 Control valves shall be rated to close off against the maximum differential pressure the hot water distribution can develop at the unit with the pump at shutoff head.
11.3.10 Each control valve actuator shall drive the valve through its full stroke within the time the control sequence allows for the heating loop to respond, and the manufacturer shall state the stroke time in the action submittal.

11.4 Steam Reheat Coil

11.4.1 Requirements in this article apply where a steam reheat coil is selected in the datasheet.
11.4.2 The design steam supply pressure at the coil shall be as indicated in the datasheet.
Design Steam Supply Pressure at the Coilrange
psig
2100
Per drawings — steam pressure as indicated on the mechanical schedules (deferred by default)
11.4.3 Steam reheat coils shall be of distributing-tube construction so that steam is delivered along the full tube length and condensate drains freely to the return connection.
11.4.4 Steam coils shall be installed so that the condensate connection is at the low point and the coil drains by gravity to the trap without a lift in the condensate line.
11.4.5 Each steam coil shall be served by a trap, a strainer, and a vacuum breaker sized by the Contractor for the scheduled coil load at the design supply pressure.
NOTE A steam coil that cannot drain fills with condensate, and the condensate is then accelerated by incoming steam into the closed end of the tube. The resulting impact damages the coil, and it is loud enough in an occupied ceiling to be reported as a building defect. (11.4.6)
11.4.7 Steam and condensate piping at the coil shall comply with Hydronic PipingHydronic PipingResolves to the current adopted revision.sync/hydronic-piping.

11.5 Electric Reheat

11.5.1 Requirements in this article apply where electric resistance reheat is selected in the datasheet.
11.5.2 The electric reheat capacity shall be as indicated in the datasheet.
Electric Reheat Capacityrange
kW
0.550
Per drawings — heater capacity as indicated on the terminal unit schedule (deferred by default)
11.5.3 The electric heater element construction shall be as indicated in the datasheet.
Electric Heater Element Constructionradio
● Open-coil nickel-chromium resistance wire on ceramic insulators
○ Sheathed tubular element without fins
○ Finned tubular sheathed element
NOTE An open-coil element transfers heat directly from the resistance wire to the airstream, which gives it a fast response and the lowest first cost and leaves the energized wire exposed to whatever the airstream carries. A sheathed element places a metal barrier between the wire and the air, which tolerates contaminated or intermittent airflow at a higher first cost and a slower thermal response. (11.5.4)
11.5.5 The electric heater capacity control method shall be as indicated in the datasheet.
Electric Heater Capacity Control Methodradio
● Staged contactors
○ Solid-state relay with time-proportioned staging
○ Silicon-controlled rectifier providing a modulating output
11.5.6 The electric heater stage count shall be as indicated in the datasheet.
Electric Heater Stage Countrange
stages
1234
Per drawings — heater staging as indicated on the terminal unit schedule (deferred by default)
NOTE Staged control moves the discharge temperature in steps whose height is the capacity of one stage divided by the airflow, so the step is largest where the heater is large relative to the minimum airflow. Where the zone has a narrow setpoint band or a low heating airflow, that step appears at the diffuser as a cycle the occupants feel. Modulating control removes the step at the cost of a device that generates electrical harmonics and requires its own thermal management. (11.5.7)
11.5.8 The electric reheat supply voltage shall be as indicated in the datasheet.
Electric Reheat Supply Voltagerange
V
120208240277480600
Per drawings — electrical drawings and panel schedules (deferred by default)
11.5.9 The electric reheat supply phase shall be as indicated in the datasheet.
Electric Reheat Supply Phaseradio
○ Single phase, 1Φ
○ Three phase, 3Φ
Per drawings — electrical drawings and panel schedules (deferred by default)
11.5.10 The heater electrical characteristics shown on the mechanical schedule and those shown on the electrical documents shall be reconciled before the heater is released for fabrication, and any discrepancy shall be resolved by the Engineer of Record.
11.5.11 Every electric heater shall be furnished with a primary automatic-reset thermal cutout.
11.5.12 Every electric heater shall be furnished with a secondary manual-reset thermal cutout independent of the primary cutout.
11.5.13 Every electric heater shall be furnished with an airflow proving device that de-energizes the heater whenever primary airflow falls below the minimum airflow the manufacturer requires for heater operation.
NOTE An electric heater energized without airflow raises the element to a temperature limited only by radiation and by the cutouts, and the cutout is a backstop rather than a control. Airflow proof is therefore a hard interlock, not a software permissive, and it is the requirement in this standard that admits no project-specific exception. (11.5.14)
11.5.15 The airflow proving interlock shall be wired in series with the heater control circuit so that a controller failure, a network failure, or a software error cannot energize the heater without airflow.
11.5.16 The manufacturer shall state the minimum airflow required for heater operation for each scheduled unit, and the controller minimum airflow in heating shall not be set below that value.
11.5.17 The electric heater accessories furnished shall be as indicated in the datasheet.
Electric Heater Accessories Furnishedcheckbox
☑ Door interlock disconnect switch
☐ Branch-circuit fusing within the heater enclosure
☐ Control power transformer within the heater enclosure
☑ Magnetic contactor for each stage
☐ Current-limiting fuse for the modulating power device
☐ Heater section removable without disturbing the duct connection
11.5.18 The electric reheat disconnecting means shall be as indicated in the datasheet.
Electric Reheat Disconnecting Meansradio
● Disconnecting means factory-installed within the heater enclosure
○ Disconnecting means field-installed within sight of the unit
○ Lockable disconnecting means at the branch panelboard

12 Fan Section

12.1 Fan and Motor

12.1.1 Requirements in this article apply where a parallel or series fan section arrangement is selected in the datasheet.
12.1.2 The fan wheel type shall be as indicated in the datasheet.
Fan Wheel Typeradio
● Forward-curved centrifugal
○ Backward-inclined centrifugal
○ Mixed-flow
12.1.3 The fan motor type shall be as indicated in the datasheet.
Fan Motor Typeradio
● Electronically commutated motor
○ Permanent split capacitor motor
NOTE An electronically commutated motor holds high efficiency across its speed range and accepts a speed command directly, so output is set during commissioning by changing a signal rather than by changing a tap or a pulley. A permanent split capacitor motor is efficient near its design point and falls away sharply below it, and its output is set in discrete steps at the winding taps. (12.1.4)
12.1.5 The fan motor nameplate power shall be as indicated in the datasheet.
Fan Motor Nameplate Powerrange
hp
0.030.050.0830.1250.1670.250.3330.50.7511.52
Per drawings — motor power as indicated on the terminal unit schedule (deferred by default)
12.1.6 The fan motor supply voltage shall be as indicated in the datasheet.
Fan Motor Supply Voltagerange
V
115208230277460480
Per drawings — electrical drawings and panel schedules (deferred by default)
12.1.7 The fan motor supply phase shall be as indicated in the datasheet.
Fan Motor Supply Phaseradio
○ Single phase, 1Φ
○ Three phase, 3Φ
Per drawings — electrical drawings and panel schedules (deferred by default)
12.1.8 The fan airflow at the design operating point shall be as indicated in the datasheet.
Fan Airflow at the Design Operating Pointrange
cfm
505000
Per drawings — fan airflow as indicated on the terminal unit schedule (deferred by default)
12.1.9 Fan motors shall comply with the applicable construction and performance provisions of NEMA MG 1.
12.1.10 The manufacturer shall state the fan airflow and the fan power at the design operating point, derived from testing in accordance with ANSI/AMCA 210, in the action submittal.
12.1.11 The fan and motor assembly shall be removable through the access panel without disconnecting the primary inlet duct, the outlet duct, or the reheat piping.
12.1.12 The fan and motor assembly shall be mounted on vibration isolators selected so that no fan-generated vibration is transmitted through the casing to the hangers.

12.2 Fan Speed Control

12.2.1 The fan speed control means shall be as indicated in the datasheet.
Fan Speed Control Meansselect
Fixed speed set at the motor taps during startup
Adjustable speed set at a potentiometer on the unit
Modulating speed commanded by the zone controller over an analog output
Modulating speed commanded by the zone controller over the network
12.2.2 The speed control means available to a unit is constrained by the motor selected: a permanent split capacitor motor accepts only the discrete speeds its winding taps provide, while an electronically commutated motor accepts a continuous speed command. The two selections shall be made together.
12.2.3 The as-commissioned fan speed setting shall be recorded for each unit in the field commissioning record.

12.3 Induced-Air Opening

12.3.1 The induced-air opening backdraft damper shall be as indicated in the datasheet.
Induced-Air Opening Backdraft Damperradio
● Gravity-operated backdraft damper
○ Motorized damper interlocked with fan operation
○ No backdraft damper
12.3.2 The induced-air opening filter shall be as indicated in the datasheet.
Induced-Air Opening Filterselect
No filter at the induced-air opening
Cleanable aluminum mesh filter
Disposable pleated filter rated MERV 8 to ANSI/ASHRAE 52.2
Disposable pleated filter rated MERV 11 to ANSI/ASHRAE 52.2
Disposable pleated filter rated MERV 13 to ANSI/ASHRAE 52.2
NOTE Where a parallel fan section is selected, primary air at the outlet is at a higher pressure than the plenum whenever the fan is off, so without a backdraft damper the unit discharges conditioned primary air into the return plenum through the induced-air opening at every cooling hour. (12.3.3)
12.3.4 The filter at the induced-air opening shall be accessible for replacement or cleaning through the unit access panel without removing the unit from its hangers.

13 Sound Performance

13.1 Rating Basis

13.1.1 Radiated and discharge sound power shall be reported separately for each scheduled unit in octave bands 2 through 7, at the scheduled primary airflow and at the scheduled inlet static pressure.
13.1.2 Occupied-space sound levels shall be estimated from the reported sound power in accordance with ANSI/AHRI 885, and the submittal shall state the room absorption, the unit-to-listener distance, and the ceiling and plenum attenuation values used.
NOTE Radiated sound leaves the casing and passes through the ceiling construction directly into the space below the unit, while discharge sound travels down the outlet duct and is attenuated by the duct, its lining, any plenum, and the outlet itself before it reaches the room. For a unit in an acoustically absorbent lay-in ceiling over an open plan, the radiated path usually reaches the listener with the least attenuation of the two. (13.1.3)
13.1.4 Sound criteria expressed as noise criteria values shall be evaluated by the tangent method of ANSI/ASA S12.2 where field measurement is performed.

13.2 Occupied-Space Sound Limits

13.2.1 The maximum radiated sound level in the occupied space attributable to the terminal unit shall be as indicated in the datasheet.
Maximum Radiated Sound Level in the Occupied Spacerange
NC
152025303540455055
13.2.2 The maximum discharge sound level in the occupied space attributable to the terminal unit shall be as indicated in the datasheet.
Maximum Discharge Sound Level in the Occupied Spacerange
NC
152025303540455055
NOTE Sound criteria vary by how the space is used, and the ranges commonly applied are: (13.2.3)
  • NC 20 to NC 25 for performance spaces, recording and broadcast rooms, and sound-critical research areas
  • NC 25 to NC 30 for executive offices, board rooms, courtrooms, and worship spaces
  • NC 30 to NC 35 for private offices, classrooms, conference rooms, patient rooms, and operating rooms
  • NC 35 to NC 40 for open offices, libraries, laboratories, retail sales areas, and restaurants
  • NC 40 to NC 45 for corridors, lobbies, public circulation, and light industrial spaces
  • NC 45 to NC 50 for kitchens, gymnasiums, and mechanical and service areas
13.2.4 Where the Contract Documents indicate a lower sound limit for a specific space, that limit shall govern in that space.
13.2.5 The unit selection submitted for each scheduled zone shall demonstrate compliance with the applicable limit using the actual room volume, room absorption, ceiling construction, and unit-to-listener distance for that zone.

13.3 Discharge Attenuation

13.3.1 The discharge attenuation provided beyond the unit casing shall be as indicated in the datasheet.
Discharge Attenuation Beyond the Unit Casingselect
No attenuation beyond the unit casing
Lined discharge plenum furnished with the unit
Lined discharge plenum furnished under the ductwork scope
Sound attenuator in the discharge duct
13.3.2 Where a lined discharge plenum is provided, its pressure drop at the primary maximum airflow shall be included in the branch pressure calculation.
NOTE Discharge attenuation added to a unit does nothing for the radiated path, so a unit selected on discharge sound alone and then found noisy in the room is rarely improved by treating the duct. (13.3.3)
13.3.4 Downstream duct and outlet selections that affect the discharge path shall be coordinated with HVAC DuctworkHVAC DuctworkResolves to the current adopted revision.sync/hvac-ductwork and HVAC Air Distribution DevicesHVAC Air Distribution DevicesResolves to the current adopted revision.sync/hvac-air-distribution-devices.

14 Zone Control and Building Automation Interface

14.1 Controller and Responsibility

14.1.1 The zone control type shall be as indicated in the datasheet.
Zone Control Typeselect
Networked direct digital controller
Standalone direct digital controller with no network connection
Analog electronic control
Pneumatic control
14.1.2 The controller furnishing and mounting responsibility shall be as indicated in the datasheet.
Controller Furnishing and Mounting Responsibilityselect
Furnished and factory-mounted by the terminal unit manufacturer
Furnished by the terminal unit manufacturer and shipped loose for field mounting
Furnished by the controls contractor and shipped to the terminal unit manufacturer for factory mounting
Furnished by the controls contractor and field-mounted
14.1.3 The controller programming and startup responsibility shall be as indicated in the datasheet.
Controller Programming and Startup Responsibilityradio
○ Programmed and tested at the factory by the terminal unit manufacturer
● Programmed at startup by the controls contractor
○ Programmed at startup by the terminal unit manufacturer's authorized representative
14.1.5 The party responsible for programming shall also be responsible for the cost of any reprogramming required to correct a sequence that does not match the Contract Documents.

14.2 Network Protocol and Points

14.2.1 The controller network protocol shall be as indicated in the datasheet.
Controller Network Protocolselect
BACnet MS/TP to ANSI/ASHRAE 135
BACnet/IP to ANSI/ASHRAE 135
BACnet Secure Connect to ANSI/ASHRAE 135
Modbus RTU
LonWorks FT-10
Wireless mesh with a gateway to a wired network
Manufacturer-proprietary protocol with a gateway to a wired network
14.2.2 The controller points required at each terminal unit shall be as indicated in the datasheet.
Required Controller Pointscheckbox
☑ Primary damper actuator output, modulating
☑ Primary airflow sensor input, differential pressure
☑ Zone temperature sensor input
☑ Discharge air temperature sensor input
☐ Hot water reheat valve output, modulating
☐ Steam reheat valve output, modulating
☐ Electric reheat stage outputs, binary
☐ Electric reheat modulating output
☐ Fan start and stop output, binary
☐ Fan speed output, modulating
☐ Fan status input, binary
☐ Zone carbon dioxide sensor input
☐ Occupancy sensor input
☐ Window or door contact input
☐ Condensate overflow switch input
14.2.3 The controller shall be furnished with sufficient spare hardwired points of each type used to accommodate the points indicated in the datasheet without an expansion module.
14.2.4 The zone control sequence basis shall be as indicated in the datasheet.
Zone Control Sequence Basisradio
○ Terminal unit sequences of ASHRAE Guideline 36
● Project-specific sequence included in the Contract Documents
○ Terminal unit manufacturer's published application sequence
14.2.5 Controller addressing, network segmentation, and supervisory controller assignment shall be established against the unit tag schedule before the units are released for shipment.
14.2.6 Where a controller is addressed at the factory, the address shall match the unit tag schedule, and the unit shall be labeled with both the tag and the address.
NOTE Re-addressing a controller in the field is a normal operation, and each occurrence introduces an opportunity for a duplicate address on a trunk that presents at commissioning as an intermittent communication fault on units unrelated to the one being changed. (14.2.7)
14.2.8 The controller and the network shall be commissioned on the project network in accordance with Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system.

14.3 Zone Sensor

14.3.1 The zone sensor measured parameters shall be as indicated in the datasheet.
Zone Sensor Measured Parameterscheckbox
☑ Dry-bulb temperature
☐ Relative humidity
☐ Carbon dioxide concentration
☐ Occupancy
☐ Total volatile organic compounds
14.3.2 The zone sensor occupant interface shall be as indicated in the datasheet.
Zone Sensor Occupant Interfaceselect
No occupant adjustment
Setpoint adjustment within a limited band
Setpoint adjustment within a limited band and a timed override button
Digital display with setpoint adjustment, timed override, and fan mode selection
14.3.3 The zone sensor setpoint adjustment range shall be as indicated in the datasheet, expressed as the permitted deviation above and below the system setpoint.
Zone Sensor Setpoint Adjustment Rangerange
°F
1234510
14.3.4 The zone sensor connection shall be as indicated in the datasheet.
Zone Sensor Connectionradio
● Hardwired to the terminal unit controller
○ Wireless to a receiver at the terminal unit controller
NOTE A wide adjustment band gives occupants control of their own comfort and gives the building an energy result that follows occupant preference rather than the design intent; a narrow band or none holds the setpoint the design assumed and moves every comfort complaint to the facility staff. (14.3.5)
14.3.6 Zone sensors shall be located out of direct sunlight, away from a supply air path, and away from a heat-generating device, and the Contractor shall report any scheduled location that cannot meet these conditions to the Engineer of Record before rough-in.
14.3.7 Wireless zone sensors shall be furnished with a means of verifying signal quality at the sensor location during installation, and the as-installed signal quality shall be recorded in the field commissioning record.

15 Factory Testing

15.1 Each terminal unit shall be subjected to the manufacturer's production test program before shipment, and the following shall be included in that program:
  • Full-stroke operation of the primary damper, verifying the closed and full-open positions against the actuator command
  • Calibration of the primary airflow sensing element against a reference flow station, with the calibration constant recorded in the unit test record
  • Leak test of the hot water or steam coil at the specified test pressure for the manufacturer's standard duration
  • Electrical functional test of the heater section, verifying the airflow proving interlock, the primary cutout, and the secondary cutout
  • Functional test of the fan and motor assembly at the design operating point where a fan section is furnished
  • Communication and point-by-point test of the controller where the controller is factory-mounted
15.2 No unit shall ship until every test in the production test program has passed, and a unit that fails a test shall be corrected and retested at the manufacturer's expense.
15.3 The factory test witnessing requirement shall be as indicated in the datasheet.
Factory Test Witnessingradio
● Production test program with certified reports and no witness
○ Witnessed test on a sample of units of each configuration
○ Witnessed test on every unit furnished
15.4 Where a witnessed test is required, the Contractor shall give the Engineer of Record not less than ten working days notice of the test date.
15.5 Where a witnessed test is required and the units are not ready on the scheduled date, the Contractor shall bear the cost of the Engineer of Record's return visit.

16 Installation

16.1 Coordination and Service Access

16.1.1 Before ceiling suspension is installed and before ductwork is fabricated, the Contractor shall verify that each terminal unit can be installed with the service clearance the manufacturer publishes and that its access panel is reachable from below the finished ceiling.
16.1.2 Service access shall be provided to the damper actuator, the airflow sensing element, the controller, the reheat section and its valve, and the fan and motor where present.
16.1.3 Where the ceiling construction below a unit does not permit access through the ceiling itself, an access panel shall be coordinated with the finish schedule and installed below the unit access panel.
16.1.4 Where a conflict cannot be resolved without relocating a unit from its scheduled position, the Contractor shall obtain the Engineer of Record's acceptance of the revised position, including the effect on the inlet approach duct length, before installing it.

16.2 Suspension and Support

16.2.1 Terminal units shall be suspended from the building structure by threaded rod, hanger strap, or trapeze hanger attached to the mounting provisions furnished on the casing.
16.2.2 Terminal units shall not be supported by the ceiling suspension system, by connected ductwork, or by connected piping.
16.2.3 Each unit shall be supported at not fewer than four points sized for the operating weight of the unit, including the weight of a water-filled coil where one is furnished.
16.2.4 Hanger points and operating weights are as indicated on the terminal unit schedule.
16.2.5 Hanger attachment to structure shall comply with the support provisions of the SMACNA HVAC Duct Construction Standards.
16.2.6 Units shall be installed level within the tolerance the manufacturer publishes, so that a coil drains as designed and a gravity backdraft damper seats.

16.3 Primary Inlet Duct Connection

16.3.1 The primary inlet duct shall connect to the unit inlet collar with the straight duct length required by this standard, measured from the face of the collar to the nearest fitting, transition, or damper.
16.3.2 Flexible duct shall not be used within the required straight duct length at the unit inlet.
16.3.3 Where flexible duct is used beyond the required straight duct length, it shall be fully extended and shall comply with the support, bend radius, and length provisions of HVAC DuctworkHVAC DuctworkResolves to the current adopted revision.sync/hvac-ductwork.
16.3.4 The joint between the inlet duct and the unit collar shall be mechanically fastened and sealed to the duct seal class established in HVAC DuctworkHVAC DuctworkResolves to the current adopted revision.sync/hvac-ductwork.
16.3.5 A balancing damper shall not be installed within the required straight duct length upstream of the unit inlet.

16.4 Outlet Duct Connection

16.4.1 The outlet duct shall connect to the unit outlet with a transition appropriate to the outlet shape and dimensions, and shall be sealed to the duct seal class established in HVAC DuctworkHVAC DuctworkResolves to the current adopted revision.sync/hvac-ductwork.
16.4.2 Where a single unit serves multiple outlets through a common downstream plenum, the plenum shall be sized so that the velocity through it does not exceed the value used in the discharge sound estimate for that unit.
16.4.3 Where the manufacturer publishes a downstream straight duct length required to achieve the rated discharge sound, that length shall be provided before the first branch, fitting, or outlet.

16.5 Hydronic and Steam Piping Connections

16.5.1 Hot water, steam, and condensate piping serving reheat coils shall comply with Hydronic PipingHydronic PipingResolves to the current adopted revision.sync/hydronic-piping.
16.5.2 Each hot water coil shall be served by an isolation valve on the supply, an isolation valve on the return, a strainer ahead of the control valve, a means of balancing or a pressure-independent control valve, a high-point air vent, and a low-point drain.
16.5.3 Piping at the unit shall be supported independently of the terminal unit so that no piping load is carried by the casing or the coil connections.
16.5.4 Piping shall be arranged so that the coil can be removed without dismantling the piping beyond the isolation valves.
16.5.5 Hot water and steam piping within a conditioned or unconditioned plenum shall be insulated continuously, and the insulation shall not be interrupted at the unit connection.
NOTE An uninsulated run of reheat piping in a return plenum heats the return air, which the central system reads as a rise in return temperature and answers by cooling harder. The load is real, it is present at every hour the heating plant is up, and it does not appear in any zone-level measurement. (16.5.6)

16.6 Electric Power Connections

16.6.1 Electric heater branch circuits shall comply with NFPA 70 Article 424.
16.6.2 Each electric heater shall be served by a branch circuit sized for the heater nameplate load as a continuous load, with overcurrent protection coordinated with the heater manufacturer's published requirement.
16.6.3 A disconnecting means shall be provided in accordance with the disconnecting means selection indicated in the datasheet, and where a lockable means at the branch panelboard is selected, the panelboard shall be permanently labeled with the unit tags it serves.
16.6.4 Fan motor branch circuits shall be sized and protected for the motor nameplate data furnished with the approved submittal.

16.7 Control Wiring

16.7.1 Control wiring between the terminal unit controller, the zone sensor, the network trunk, and any auxiliary input shall be Class 2 cable installed in accordance with NFPA 70.
16.7.2 Cable installed in a ceiling plenum or other air-handling space shall be listed for that use.
16.7.3 Network trunk wiring shall be the twisted shielded pair the controller manufacturer specifies, with the shield continuous through every device and grounded at one point only.
16.7.4 Control wiring shall be routed and supported separately from line-voltage power wiring, and shall not be laid on ceiling tile, on pipe insulation, or on the terminal unit casing.
NOTE A shield grounded at more than one point creates a current path through the shield that couples noise into the signal it was installed to protect, and the symptom is an intermittent communication fault that moves around the trunk as devices are added. (16.7.5)

16.8 Pre-Startup Inspection

16.8.1 Before the terminal units are energized and the central air system is started, the Contractor shall confirm the following at each unit:
  • Shipping restraints, blocking, and protective films have been removed
  • The primary damper strokes freely from closed to full open
  • Airflow sensor tubing is connected at the sensing element and at the controller, and is free of kinks, crimps, and disconnected fittings
  • The hot water or steam coil is filled, vented, and pressure tested in accordance with Hydronic PipingHydronic PipingResolves to the current adopted revision.sync/hydronic-piping
  • The electric heater branch circuit is energized, control power is present at the heater, and the airflow proving device reads a no-flow condition
  • The fan and motor assembly rotates freely and in the correct direction
  • Network communication is established with the controller at its assigned address
  • The zone sensor is connected and reporting a plausible space temperature
  • Access panels are closed and the ceiling is complete
Pre-Startup Inspection Checklistcheckbox
☑ Shipping restraints and protective films removed
☑ Primary damper strokes freely through its full range
☑ Airflow sensor tubing connected and intact
☐ Reheat coil filled, vented, and pressure tested
☐ Electric heater circuit energized and airflow proving device verified
☐ Fan and motor rotate freely in the correct direction
☑ Network communication established at the assigned address
☑ Zone sensor connected and reporting a plausible temperature
☑ Access panels closed and ceiling complete
16.8.2 Terminal units shall not be operated to provide temporary heating, cooling, or ventilation during construction unless the Engineer of Record accepts the temporary use in writing and the Contractor replaces every filter and cleans every unit so operated before Substantial Completion.

17 Field Testing and Commissioning

17.1 Airflow Verification

17.1.1 The testing and balancing agent shall verify the primary airflow at each unit at the cooling maximum, the cooling minimum, and the heating airflow setpoint, in accordance with Testing Adjusting And BalancingTesting, Adjusting, and Balancing for HVACResolves to the current adopted revision.sync/testing-adjusting-and-balancing.
17.1.2 The airflow verification tolerance shall be as indicated in the datasheet, applied as a plus-or-minus band about the commanded value at each setpoint.
Airflow Verification Tolerance at Each Setpointrange
%
25101520
17.1.3 Airflow verification shall be performed with the system clean, the design filter media installed, the ceiling complete, and the central system operating at its design static pressure control setpoint.
17.1.4 Where measured airflow at a setpoint falls outside the tolerance, the calibration constant for that unit shall be adjusted against a calibrated reference instrument and the setpoint reverified.
17.1.5 The as-left calibration constant and every as-commissioned setpoint shall be recorded for each unit in the field commissioning record.
17.1.6 Where a unit cannot be brought within tolerance by adjustment of its calibration constant and its branch damper, the testing and balancing agent shall report the condition to the Engineer of Record rather than adjusting the setpoint to match the measurement.
NOTE Adjusting the commanded setpoint until it matches what the unit actually delivers makes the balancing report agree with itself and leaves the zone with an airflow the ventilation calculation never contemplated. The report then certifies the wrong number for the life of the building. (17.1.7)

17.2 Functional Performance Testing

17.2.1 The extent of functional performance testing shall be as indicated in the datasheet.
Extent of Functional Performance Testingradio
○ Not required
○ Representative sample of units of each configuration
○ Every installed unit
17.2.2 Where functional performance testing is required, it shall be conducted in accordance with ANSI/ASHRAE 202 and shall verify the zone control sequence in occupied, unoccupied, and override modes.
17.2.3 Functional performance testing shall verify the reheat output through its full range, the fan operation and induced airflow where a fan section is furnished, the airflow proving interlock where an electric heater is furnished, and the reporting of every hardwired and calculated point at the operator workstation.
17.2.4 Where a functional performance test fails, the Contractor shall correct the deficiency and shall bear the cost of retesting that unit.
17.2.5 Where a sample-based extent is selected and a unit in the sample fails, the sample for that configuration shall be doubled at the Contractor's expense.

17.3 Acoustic Verification

17.3.1 The extent of field acoustic verification shall be as indicated in the datasheet.
Extent of Field Acoustic Verificationradio
● Not required
○ Required in spaces with a sound limit of NC 30 or lower
○ Required in a representative space of each space type
○ Required in every space served by a terminal unit
17.3.2 Where acoustic verification is required, sound pressure shall be measured in octave bands at the listener position with the system operating at design airflow, with the space otherwise quiet, and the result evaluated to ANSI/ASA S12.2.
17.3.3 Where a measured level exceeds the specified limit and the excess is attributable to the terminal unit or its installation, the Contractor shall correct the condition and shall bear the cost of re-measurement.
17.3.4 Where a measured level exceeds the specified limit and the excess is attributable to a source outside the scope of this standard, the Engineer of Record shall determine the responsible scope.
NOTE Corrective actions available for an excess attributable to the terminal unit include lowering the central system static pressure setpoint through reset, adding a lined discharge plenum, upgrading the ceiling construction below the unit, and substituting a unit with a larger casing and a lower face velocity. (17.3.5)

18 Delivery, Storage, and Handling

18.1 Terminal units shall be delivered in the manufacturer's packaging with each unit marked with its project tag and with the inlet and outlet openings sealed against construction dust.
18.2 Terminal units shall be stored indoors in a clean, dry, weather-protected space until installation.
18.3 Terminal units shall not be stored on bare ground or bare slab, in standing water, or in a space subject to freezing or to water intrusion.
18.4 Stacked units shall be supported only at the corner brackets, shall not exceed the stack height the manufacturer publishes, and shall not bear on the casing wrapper.
18.5 Where a hot water or steam coil may be exposed to a storage temperature below 35 °F, the coil shall be drained, blown clear with compressed air, and tagged as drained, and a corresponding entry shall be made on the unit tag schedule so that the coil is refilled and vented before startup.
18.6 Where the ceiling is not ready to receive terminal units, the Contractor shall hold the units in protected storage rather than installing them and covering the openings.

19 Identification

19.1 Each terminal unit shall be furnished with a permanent identification label applied to the casing exterior in a location visible from below the finished ceiling.
19.2 The identification label shall state the unit tag matching the unit schedule, the manufacturer's model and serial number, the primary maximum and minimum airflow setpoints, the reheat capacity where reheat is furnished, the electrical characteristics where an electrical connection is made, the controller address where a controller is furnished, and the date of manufacture.
19.3 Identification labels shall not be applied to a removable access panel.
19.4 The identification nameplate material shall be as indicated in the datasheet.
Identification Nameplate Materialradio
● Adhesive laminated label
○ Engraved phenolic plate, mechanically fastened
○ Etched stainless steel plate, mechanically fastened
19.5 Where a unit is replaced or its configuration is changed after the label is applied, the label shall be replaced to reflect the as-installed configuration.

20 Warranty

20.1 The manufacturer shall warrant each terminal unit against defects in material and workmanship for the period indicated in the datasheet, beginning at the date of Substantial Completion.
Equipment Warranty Periodrange
years
1235
20.2 The equipment warranty shall cover the casing, the liner, the damper and its actuator, the airflow sensing element, the reheat coil or heater, the control valve and its actuator, the fan and motor, and the controller where the controller is furnished by the terminal unit manufacturer.
20.3 The manufacturer shall warrant the fan motor and its integral electronics for the period indicated in the datasheet, beginning at the date of Substantial Completion.
Fan Motor Warranty Periodrange
years
1235710
20.4 The manufacturer shall warrant the reheat coil against leakage in the tube and fin assembly for the period indicated in the datasheet, beginning at the date of Substantial Completion.
Reheat Coil Warranty Periodrange
years
123510
20.5 The Contractor shall warrant the installation, including hangers, duct and piping connections, electrical connections, control wiring, sealing, and identification, for one year from the date of Substantial Completion.
20.6 Warranty coverage shall include the cost of removing and reinstalling the ceiling, ductwork, and piping disturbed to reach a unit being repaired or replaced, and the cost of repairing collateral damage caused by that work.
20.7 Where a unit or a component is repaired or replaced under warranty, the repaired or replacement item shall carry a fresh warranty of the full original period from the date of the repair, or the remainder of the original period, whichever ends later.
20.8 The Contractor shall keep every installed unit accessible during the warranty period by keeping access panels, ceiling tiles, and adjacent construction clear of permanent obstruction.
20.9 The manufacturer shall maintain factory-trained service capability within the region of the project for the duration of the equipment warranty period.

21 Spare Parts

21.1 The Contractor shall deliver the following to the Owner at Substantial Completion:
  • One damper actuator for each actuator model installed
  • One control valve actuator for each valve size and model installed
  • One fan motor for each motor size installed on fan-powered units
  • One terminal unit controller for each controller model installed
  • Zone temperature sensors equal to five percent of the installed quantity, and not fewer than two
  • One primary thermal cutout and one secondary thermal cutout for each electric heater model installed
  • One set of induced-air filters for each filter size installed on fan-powered units
Spare Parts at Substantial Completioncheckbox
☑ One damper actuator for each actuator model
☑ One control valve actuator for each valve size and model
☐ One fan motor for each motor size on fan-powered units
☑ One terminal unit controller for each controller model
☑ Zone temperature sensors equal to five percent of the installed quantity
☐ One primary and one secondary thermal cutout for each heater model
☐ One set of induced-air filters for each filter size
21.2 Spare parts shall be delivered in the manufacturer's original packaging, each tagged with the model number, the unit tags it serves, and the date of delivery.
21.3 Spare parts shall be turned over at a storage location the Owner designates, and the transfer shall be documented in the closeout submittal.
21.4 The operation and maintenance manual shall include a spare parts inventory listing the manufacturer part number and reorder information for every component of the units furnished, so that additional spares can be procured over the service life of the installation.