+---
+title: Dedicated Outdoor Air Systems
+category: Mechanical / Air Distribution
+toc_depth: 3
+description: >
+ When to use: Packaged dedicated outdoor air systems (DOAS) that condition 100% outdoor air to satisfy the building's ventilation requirement independently of the spaces' sensible cooling and heating. Covers indoor and outdoor/rooftop units, the air-to-air energy recovery section (enthalpy wheel, fixed-plate, heat-pipe, or runaround loop), the deep-cooling and dehumidification section (integrated DX, air-source or water-source heat pump, or chilled water), the reheat method that controls leaving dewpoint and supply air temperature (hot-gas reheat, modulating reheat, wraparound heat pipe, or dehumidification wheel), the heating source, filtration, fans, casing, and the controls integration that coordinates the DOAS with the parallel sensible system it serves. Applicable to DOAS paired with variable refrigerant flow, fan coils, chilled beams, water-source heat pumps, or sensible-only rooftop units, in commercial, institutional, multifamily, and light-industrial buildings.
+ Not intended for: General mixed-air central station air handlers that recirculate return air (see [[sync/air-handling-units]]); unitary packaged rooftop units with return-air mixing and integral economizer (see [[sync/packaged-rooftop-units]]); the parallel sensible terminal equipment itself, such as variable refrigerant flow systems (see [[sync/variable-refrigerant-flow-systems]]) and air terminal units (see [[sync/air-terminal-units]]); the field refrigerant piping interconnecting split DX components (see [[sync/refrigerant-piping]]); supply and exhaust ductwork beyond the unit connections (see [[sync/hvac-ductwork]]); supply diffusers and grilles (see [[sync/hvac-air-distribution-devices]]); testing, adjusting, and balancing after installation (see [[sync/testing-adjusting-and-balancing]]); and building automation controls programming and integration (see [[sync/building-automation-system]]).
+---
+
+# Scope
+
+This specification covers factory-assembled dedicated outdoor air systems (DOAS) that draw 100% outdoor air, recover energy from the building exhaust, deep-cool and dehumidify the ventilation air to a controlled leaving dewpoint, reheat and temper the supply air as required, and deliver it to occupied spaces or to the inlets of a parallel sensible-conditioning system. Equipment covered includes the unit casing, the outdoor air and exhaust air fans, the air-to-air energy recovery section, the cooling and dehumidification section and its cooling source, the reheat section, the heating section, filtration, dampers, drain pans, and the factory controls that sequence dehumidification and reheat. Both indoor and outdoor (rooftop or grade-mounted) arrangements are addressed.
+
+A DOAS exists to solve a single problem cleanly: ventilation air is a latent-load problem, and space conditioning is mostly a sensible-load problem, and the two do not track each other. A conventional mixed-air system tries to do both with one cooling coil, which forces a compromise — to wring enough moisture out of the outdoor air it must overcool the entire supply stream, then waste energy reheating it, and at part-load it often cannot dehumidify at all because the thermostat is satisfied before the coil gets cold enough. Decoupling the two loads resolves this. The DOAS takes responsibility for the entire latent load of the building (the moisture brought in by ventilation air and, by design intent, the internal moisture generated by occupants) by delivering air at a low, controlled dewpoint, and the parallel sensible system — variable refrigerant flow, fan coils, chilled beams, water-source heat pumps, or sensible-only zone equipment — then handles only the dry sensible load of each space without ever having to dehumidify. This is why DOAS units are designed and rated around moisture removal, and why the dewpoint of the supply air, not its dry-bulb temperature alone, is the controlling design parameter.
+
+Because the DOAS conditions a full outdoor air stream year-round, two requirements dominate its design and this standard. First, air-to-air energy recovery is mandatory in most climates and at most ventilation rates under ASHRAE 90.1 — recovering energy from the exhaust stream is what makes conditioning 100% outdoor air economically viable, and the recovery device's effectiveness, frost behavior, and cross-leakage are central engineering decisions, not accessories. Second, achieving a low leaving dewpoint requires cooling the air well below the desired supply temperature and then reheating it; how that reheat is supplied (and whether it is recovered "free" reheat or purchased energy) is the second central decision. Equipment shall comply with AHRI 920 for performance rating of DX and heat-pump DOAS units, AHRI 1060 for air-to-air energy recovery ventilation equipment, AHRI 430 and AHRI 410 where central-station fans and coils are used, ASHRAE 62.1 for ventilation rates and air-stream classification, ASHRAE 90.1 for energy recovery and fan power, ASHRAE 55 for occupant comfort, the applicable AMCA fan and damper/louver standards, NFPA 90A for fire and smoke safety, and the applicable UL listing for electrical and refrigerant safety.
+
+The boundary of work under this standard is the DOAS unit and its factory components, from the outdoor air intake and exhaust air connections to the supply air discharge connection. The supply and exhaust ductwork is covered by [[sync/hvac-ductwork]]; the diffusers, grilles, and registers that distribute DOAS air are covered by [[sync/hvac-air-distribution-devices]]; the parallel sensible terminal equipment is covered by its own standards; field refrigerant piping for split DX arrangements is covered by [[sync/refrigerant-piping]]; chilled water and hot water piping to coils is covered by the hydronic piping standard; and controls programming, graphics, and trending are covered by [[sync/building-automation-system]].
+
+# 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 adopted energy and mechanical codes, the equipment manufacturer's instructions, or the contract documents, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+| Standard | Title |
+|----------|-------|
+| ANSI/AHRI 920 (I-P) | Performance Rating of DX-Dedicated Outdoor Air System Units |
+| ANSI/AHRI 1060 (I-P) | Performance Rating of Air-to-Air Exchangers for Energy Recovery Ventilation Equipment |
+| ANSI/AHRI 430 (I-P) | Performance Rating of Central Station Air-handling Unit Supply Fans |
+| ANSI/AHRI 410 | Performance Rating of Forced-Circulation Air-Cooling and Air-Heating Coils |
+| ANSI/ASHRAE 51 / ANSI/AMCA 210 | Laboratory Methods of Testing Fans for Certified Aerodynamic Performance Rating |
+| ANSI/AMCA 300 | Reverberation Room Methods of Sound Testing of Fans |
+| ANSI/AMCA 500-L | Laboratory Methods of Testing Louvers for Rating |
+| ANSI/AMCA 500-D | Laboratory Methods of Testing Dampers for Rating |
+| ANSI/ASHRAE 52.2 | Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size |
+| ANSI/ASHRAE 62.1 | Ventilation and Acceptable Indoor Air Quality |
+| ANSI/ASHRAE 55 | Thermal Environmental Conditions for Human Occupancy |
+| ANSI/ASHRAE/IES 90.1 | Energy Standard for Buildings Except Low-Rise Residential Buildings |
+| ANSI/ASHRAE 170 | Ventilation of Health Care Facilities (where DOAS serves health-care spaces) |
+| ASHRAE Guideline 36 | High-Performance Sequences of Operation for HVAC Systems |
+| NFPA 90A | Standard for the Installation of Air-Conditioning and Ventilating Systems |
+| UL 1995 | Heating and Cooling Equipment (where accepted by AHJ) |
+| UL 60335-2-40 | Safety of Household and Similar Electrical Appliances — Particular Requirements for Heat Pumps, Air-Conditioners, and Dehumidifiers |
+| SMACNA HVAC Duct Construction Standards | SMACNA HVAC Duct Construction Standards — Metal and Flexible |
+| ASHRAE Handbooks | HVAC Systems and Equipment, Fundamentals, Applications |
+
+# Submittals
+
+## Action Submittals
+
+The Contractor shall submit the following for the Engineer's review and acceptance before equipment is ordered. Fabrication and procurement shall not proceed until action submittals have been reviewed and returned. Submittals shall be internally coordinated with the parallel sensible system and with the building automation system before any item is submitted.
+
+- Manufacturer's product data for each DOAS unit, including model designation, an airflow schematic showing the sequence of energy recovery, cooling, reheat, heating, and filter sections, and the component schedule
+- AHRI 920 certified performance ratings for DX and heat-pump units, including the integrated seasonal moisture removal efficiency (ISMRE2, or ISMRE270 where the unit reheats to a neutral leaving temperature with supplemental heat) and, for heat-pump units, the integrated seasonal coefficient of performance (ISCOP2)
+- AHRI 1060 certified performance ratings for the energy recovery component, including sensible and latent effectiveness at 100% and 75% of rated airflow for both summer and winter conditions, the exhaust air transfer ratio (EATR), and the outdoor air correction factor (OACF)
+- A psychrometric analysis for each unit plotting the air state points (entering outdoor air, after energy recovery, after the cooling/dehumidification coil, and supply air) at the cooling/dehumidification design condition, and the corresponding heating-season state points, with the leaving dewpoint and supply air temperature at each
+- Capacity data at the cooling design condition and at the specified part-load (turndown) condition, demonstrating that the unit holds the leaving dewpoint setpoint at reduced ventilation flow and reduced load, where part-load dehumidification is required
+- Fan performance curves at the design operating point per AHRI 430 / AMCA 210, with power and efficiency, and octave-band sound power levels per AMCA 300 for both supply discharge and casing radiation
+- Coil selection data per AHRI 410 for cooling, reheat, and heating coils, with entering and leaving conditions, face velocity, rows, fin spacing, and air- and water-side pressure drop
+- Filter section data with MERV rating certified per ASHRAE 52.2, initial and final resistance, and frame and seal construction
+- Casing construction details, panel R-value, interior liner material, and, for outdoor units, the weatherproofing and finish system
+- Energy recovery frost-control description (the method, the outdoor temperature at which it activates, and its effect on ventilation delivery during frost control)
+- A controls points list and a written sequence of operation describing dehumidification control, reheat control, supply air temperature/dewpoint reset, energy recovery bypass and frost control, and the interface to the parallel sensible system and the [[sync/building-automation-system]]
+- Electrical data: voltage, phase, minimum circuit ampacity, maximum overcurrent protection, and the refrigerant type and charge for DX and heat-pump units
+
+```datasheet
+label: Action Submittals Required
+type: checkbox
+options:
+ - "Product data and unit airflow schematic"
+ - "AHRI 920 performance ratings (ISMRE2 / ISMRE270 / ISCOP2)"
+ - "AHRI 1060 energy recovery ratings (effectiveness, EATR, OACF)"
+ - "Psychrometric state-point analysis (design and heating)"
+ - "Capacity at design and part-load dehumidification"
+ - "Fan curves and AMCA 300 sound power levels"
+ - "Coil selection data (AHRI 410)"
+ - "Filter MERV certification (ASHRAE 52.2)"
+ - "Casing construction and weatherproofing details"
+ - "Energy recovery frost-control description"
+ - "Controls points list and sequence of operation"
+ - "Electrical data and refrigerant charge"
+default: "Product data and unit airflow schematic"
+```
+
+## Closeout Submittals
+
+The Contractor shall provide the following at or before substantial completion:
+
+- Operation and maintenance manuals for each unit and all major components, organized with a table of contents
+- As-built unit configuration and as-built controls points list reflecting any field modifications
+- Factory test reports for each unit
+- Startup and commissioning records, including the functional test of dehumidification, reheat, energy recovery frost control, and the interlock to the parallel sensible system
+- Refrigerant charging records (DX and heat-pump units), documenting refrigerant type and total charge
+- Energy recovery component maintenance data, including wheel drive belt and seal replacement intervals for rotary devices, and core cleaning procedure for fixed-plate devices
+- Filter media installed at substantial completion with MERV certification and installation date tags
+- Warranty documentation from the manufacturer and from any compressor and energy recovery sub-suppliers
+
+# Quality Assurance
+
+## Manufacturer Qualifications
+
+DOAS units shall be manufactured by a company with a minimum of ten years of continuous experience designing and fabricating packaged ventilation and air-conditioning equipment, maintaining a quality management system, and able to provide replacement parts and factory service support for a minimum of fifteen years after the date of manufacture.
+
+## Single-Source Responsibility
+
+For each DOAS unit, the casing, fans, energy recovery section, cooling and dehumidification section, reheat and heating sections, filters, and dampers shall be provided as a coordinated factory assembly by or through the DOAS manufacturer. The interaction between the energy recovery device, the dehumidification coil, and the reheat source is what determines whether the unit actually holds its leaving dewpoint; resolving that interaction at the factory rather than assembling independent components in the field is the reason for the single-source requirement.
+
+## AHRI Certification
+
+DX and heat-pump DOAS units shall be rated under the AHRI Certification Program for DX-Dedicated Outdoor Air System Units per AHRI 920, and published ISMRE2, ISMRE270 (where applicable), and ISCOP2 ratings shall bear the AHRI certification mark. Air-to-air energy recovery components shall be rated under the AHRI Certification Program for energy recovery ventilation equipment per AHRI 1060, and the published effectiveness, EATR, and OACF shall bear the AHRI certification mark. Where central-station fans and coils are used, ratings shall conform to AHRI 430 and AHRI 410. AHRI-certified ratings, not generic catalog values, shall be the basis of selection.
+
+```datasheet
+label: AHRI Certification Required
+type: checkbox
+options:
+ - "DOAS unit performance per AHRI 920 (ISMRE2 / ISCOP2)"
+ - "Energy recovery component per AHRI 1060"
+ - "Supply fan performance per AHRI 430"
+ - "Coils per AHRI 410"
+default: "DOAS unit performance per AHRI 920 (ISMRE2 / ISCOP2)"
+```
+
+## Factory Run Test
+
+Each unit shall receive a factory functional run test before shipment, operating the refrigeration or heat-pump circuit (where integral), the fans, the energy recovery drive, and the dehumidification and reheat sequence, and confirming that the unit produces the specified leaving dewpoint at the test condition. A factory test report shall be submitted at closeout.
+
+## NRTL Listing
+
+The complete DOAS assembly, including all electrical and (where integral) refrigerant components, shall be listed and labeled by a Nationally Recognized Testing Laboratory to UL 60335-2-40, or to UL 1995 where the Authority Having Jurisdiction continues to accept that listing for equipment manufactured before the transition date.
+
+# Environmental and Service Conditions
+
+The unit shall be selected and rated for the design conditions at the installation site. The design outdoor air condition, the supply air leaving condition, and the exhaust air entering condition are [[drawing: as indicated on the mechanical schedules and the psychrometric process diagrams]].
+
+## Design Outdoor Air Condition
+
+Because the DOAS conditions 100% outdoor air, it shall be selected at the project's dehumidification design condition — the design dewpoint or design wet-bulb condition from ASHRAE Fundamentals for the project location — and not merely at the cooling dry-bulb design. The dehumidification design condition, which typically pairs a moderate dry-bulb with a high coincident moisture content, is the condition that sizes the cooling coil and the reheat, and it is frequently more demanding for a DOAS than the peak dry-bulb hour.
+
+```datasheet
+label: Cooling/Dehumidification Design Outdoor Air Condition
+type: text
+drawing_ref: true
+default: "Per ASHRAE 0.4% dehumidification design dewpoint for project location (see mechanical schedules)"
+```
+
+```datasheet
+label: Heating Design Outdoor Air Temperature
+type: range
+unit: °F
+drawing_ref: true
+options:
+ min: -30
+ max: 40
+ setpoints: [-30, -20, -10, 0, 10, 20, 30, 40]
+default: 0
+```
+
+## Supply Air Leaving Targets
+
+The controlling leaving condition is the supply air dewpoint, because the DOAS is selected to absorb the building latent load. The leaving dewpoint setpoint shall be low enough that the DOAS supply air, after mixing with space air and absorbing the space moisture gains, holds the space relative humidity within the design range under ASHRAE 55. A leaving dewpoint of about 50°F to 55°F is typical for comfort applications; lower dewpoints are specified for spaces with strict humidity limits.
+
+```datasheet
+label: Supply Air Leaving Dewpoint Setpoint
+type: range
+unit: °F
+drawing_ref: true
+options:
+ min: 40
+ max: 58
+ setpoints: [40, 45, 48, 50, 52, 55, 58]
+default: 52
+```
+
+```datasheet
+label: Supply Air Dry-Bulb Strategy
+type: radio
+options:
+ - "Neutral supply — reheat ventilation air to near space-neutral temperature (68-72°F); space load carried entirely by parallel sensible system (standard)"
+ - "Cold (DOAS-to-space) supply — deliver cool, dry air directly to the space to offset part of the sensible load; reheat only to the dewpoint-control minimum"
+ - "Reset supply temperature — neutral in cooling season, warm (tempered) in heating season"
+default: "Neutral supply — reheat ventilation air to near space-neutral temperature (68-72°F); space load carried entirely by parallel sensible system (standard)"
+```
+
+A neutral-supply DOAS delivers ventilation air at a temperature close to the space setpoint so it neither heats nor cools the space; the parallel sensible system carries the full space load. This is the most common and the most forgiving arrangement, because the parallel system and the DOAS never fight each other. A cold-supply (DOAS-to-space) arrangement intentionally delivers cool dry air to offset part of the space sensible load, which reduces the parallel system's capacity but requires careful diffuser selection to avoid drafts and requires that the parallel system not overcool and drive the space humidity back up. The cold-supply strategy decouples humidity control from the parallel system only if the DOAS dewpoint is held independent of its dry-bulb — which is exactly what the reheat section provides.
+
+## Unit Installation Location
+
+```datasheet
+label: Unit Installation Location
+type: select
+options:
+ - "Outdoor — rooftop on roof curb"
+ - "Outdoor — grade-mounted on housekeeping pad"
+ - "Indoor — mechanical room or penthouse"
+default: "Outdoor — rooftop on roof curb"
+```
+
+# Unit Configuration and Arrangement
+
+The following decisions define the unit. They are interdependent — the energy recovery type, the cooling source, the dehumidification and reheat method, and the supply strategy must be selected together — and they should be reviewed against the psychrometric analysis as a set.
+
+## Airflow Capacity
+
+Design outdoor (ventilation) airflow and exhaust airflow shall be [[drawing: as indicated on the mechanical schedules]]. The ventilation rate shall be established by the ASHRAE 62.1 ventilation rate procedure for the served spaces.
+
+```datasheet
+label: Design Outdoor Air (Ventilation) Airflow
+type: range
+unit: cfm
+drawing_ref: true
+options:
+ min: 500
+ max: 60000
+ step: 250
+default: 4000
+```
+
+```datasheet
+label: Exhaust Air Airflow Through Energy Recovery
+type: range
+unit: cfm
+drawing_ref: true
+options:
+ min: 0
+ max: 60000
+ step: 250
+default: 3500
+```
+
+## External Static Pressure
+
+```datasheet
+label: Supply External Static Pressure
+type: range
+unit: in. wg
+drawing_ref: true
+options:
+ min: 0.5
+ max: 4.0
+ setpoints: [0.5, 0.75, 1.0, 1.25, 1.5, 2.0, 2.5, 3.0, 4.0]
+default: 1.5
+```
+
+## Configuration Summary
+
+```datasheet
+label: Energy Recovery Type
+type: select
+options:
+ - "Enthalpy (total energy) rotary wheel"
+ - "Sensible-only rotary wheel with purge sector"
+ - "Fixed-plate enthalpy (membrane) core"
+ - "Fixed-plate sensible (aluminum) core"
+ - "Heat-pipe (sensible)"
+ - "Runaround coil loop (sensible, separated air streams)"
+ - "None (energy recovery not required by code for this unit)"
+default: "Enthalpy (total energy) rotary wheel"
+```
+
+```datasheet
+label: Cooling Source
+type: select
+options:
+ - "Integrated DX (packaged compressorized cooling)"
+ - "Air-source heat pump (DX cooling and heating)"
+ - "Water-source heat pump (DX, condenser water loop)"
+ - "Chilled water coil (central plant)"
+default: "Integrated DX (packaged compressorized cooling)"
+```
+
+```datasheet
+label: Dehumidification Reheat Method
+type: select
+options:
+ - "Hot-gas (refrigerant) reheat — recovered condenser heat (DX/heat-pump units)"
+ - "Modulating hot-gas reheat — variable leaving-temperature control"
+ - "Wraparound heat pipe — passive precool/reheat around the cooling coil"
+ - "Wraparound runaround coil — pumped passive reheat"
+ - "Dehumidification (passive desiccant) wheel — sensible reheat from process air"
+ - "Hot water or electric reheat coil — purchased reheat energy"
+ - "None — supply delivered cold (cold-supply strategy)"
+default: "Hot-gas (refrigerant) reheat — recovered condenser heat (DX/heat-pump units)"
+```
+
+```datasheet
+label: Heating Source
+type: select
+options:
+ - "Heat pump (integral, air-source or water-source)"
+ - "Indirect gas-fired furnace"
+ - "Electric resistance heating coil"
+ - "Hot water heating coil (central plant)"
+ - "None — supplemental heating provided downstream"
+default: "Heat pump (integral, air-source or water-source)"
+```
+
+```datasheet
+label: Supply Air Strategy
+type: radio
+options:
+ - "Neutral supply (standard)"
+ - "Cold supply (DOAS-to-space)"
+ - "Reset (neutral cooling, tempered heating)"
+default: "Neutral supply (standard)"
+```
+
+```datasheet
+label: Filtration (Final Filter MERV)
+type: select
+options:
+ - "MERV 8 — minimum for ventilation air"
+ - "MERV 11 — enhanced commercial"
+ - "MERV 13 — fine particulate (PM2.5), standard for occupied ventilation"
+ - "MERV 14 — superior filtration"
+default: "MERV 13 — fine particulate (PM2.5), standard for occupied ventilation"
+```
+
+```datasheet
+label: Fan Type
+type: radio
+options:
+ - "Direct-drive plenum (plug) fan with ECM or VFD-driven motor (standard)"
+ - "Direct-drive backward-curved plenum fan, VFD-driven"
+ - "Belt-driven centrifugal fan (legacy / large units)"
+default: "Direct-drive plenum (plug) fan with ECM or VFD-driven motor (standard)"
+```
+
+# Energy Recovery
+
+Air-to-air energy recovery is the feature that makes a DOAS practical. Conditioning a full outdoor air stream from a hot, humid summer condition or a cold, dry winter condition to the supply condition is a large load; recovering most of that load from the building exhaust, which is already near the space condition, cuts the cooling and heating capacity the unit must purchase by half or more. ASHRAE 90.1 requires exhaust air energy recovery for most ventilation systems based on the percentage of outdoor air and the design supply airflow, with a minimum enthalpy recovery ratio (the ratio of recovered enthalpy to the maximum available) of at least 50% at the design condition for the climate zone. Recovery shall be provided wherever required by the adopted energy code; the only DOAS units that omit it are those that fall below the code threshold or that qualify for a specific exception.
+
+## Recovery Device Type — Sensible vs. Total
+
+The first recovery decision is whether to recover latent energy (moisture) as well as sensible energy (temperature), and that decision turns on the application. Total-energy (enthalpy) devices — rotary enthalpy wheels and fixed-plate membrane cores — transfer both heat and moisture between the air streams. In a DOAS this is usually the right choice: in summer the enthalpy device pre-dries the incoming air using the drier exhaust, reducing the latent load on the cooling coil; in winter it returns moisture to the incoming air, reducing dry indoor conditions and the need for humidification. Sensible-only devices — heat pipes, sensible plates, sensible wheels, and runaround loops — transfer heat only. A sensible device is selected where moisture transfer is undesirable or prohibited: where the exhaust is contaminated and any cross-transfer to the supply is unacceptable, or where the design intent is to maximize the moisture removed by the cooling coil rather than recover it.
+
+```datasheet
+label: Recovery — Sensible or Total Energy
+type: radio
+options:
+ - "Total energy (sensible + latent) — recover moisture; reduces coil latent load (standard for comfort DOAS)"
+ - "Sensible only — temperature recovery, no moisture transfer (contaminated exhaust or no-cross-transfer applications)"
+default: "Total energy (sensible + latent) — recover moisture; reduces coil latent load (standard for comfort DOAS)"
+```
+
+## Cross-Contamination and EATR
+
+Rotary wheels and any device with a shared interface carry a small amount of air from the exhaust stream into the supply stream. AHRI 1060 quantifies this as the exhaust air transfer ratio (EATR) and the outdoor air correction factor (OACF). Where the exhaust is ASHRAE 62.1 Class 1 air (general comfort exhaust), a small EATR is acceptable. Where the exhaust contains Class 2 air, ASHRAE 62.1 limits the EATR to no more than 10% and requires that any transferred air be accounted for in the ventilation calculation; where the exhaust is Class 3 or Class 4, energy recovery that allows cross-transfer is prohibited and a sensible device with fully separated streams (heat pipe or runaround loop) shall be used. Rotary wheels intended for Class 1/Class 2 service shall include a purge sector, which uses a small pressure-driven flow to sweep carryover air back to the exhaust before the wheel rotates into the supply stream, reducing EATR.
+
+```datasheet
+label: Exhaust Air Stream Classification (ASHRAE 62.1)
+type: select
+options:
+ - "Class 1 — general comfort exhaust (any recovery type acceptable)"
+ - "Class 2 — moderate-contaminant exhaust (EATR ≤ 10%; purge required on wheels)"
+ - "Class 3/4 — high-contaminant exhaust (separated-stream sensible recovery only)"
+default: "Class 1 — general comfort exhaust (any recovery type acceptable)"
+```
+
+```datasheet
+label: Rotary Wheel Purge Sector
+type: radio
+options:
+ - "Purge sector required (Class 2 exhaust or low-EATR requirement)"
+ - "Purge sector not required (Class 1 exhaust)"
+ - "Not applicable (non-rotary recovery device)"
+default: "Purge sector not required (Class 1 exhaust)"
+```
+
+## Frost Control
+
+In cold climates the warm, moist exhaust gives up its moisture as it is cooled by the incoming air, and that moisture can freeze on the recovery surface, blocking the exhaust path and destroying recovery. Every recovery device in a freezing climate shall have a defined frost-control strategy, and the strategy chosen affects the unit's ventilation delivery at the coldest hours. Wheels are frost-controlled by modulating wheel speed or by a timed defrost; fixed plates and heat pipes are frost-controlled by preheating the incoming air, by an exhaust-side bypass, or by recirculation. The frost-control method, its activation temperature, and its effect on ventilation flow during frost control shall be submitted.
+
+```datasheet
+label: Energy Recovery Frost Control Method
+type: select
+options:
+ - "Modulating wheel speed (rotary wheels)"
+ - "Timed defrost cycle (rotary wheels)"
+ - "Preheat of entering outdoor air upstream of recovery (plates, heat pipes)"
+ - "Exhaust-side or supply-side bypass damper"
+ - "Not required (climate does not produce recovery frost)"
+default: "Not required (climate does not produce recovery frost)"
+```
+
+## Recovery Bypass
+
+A bypass damper around the recovery device shall be provided where the recovery would otherwise be active during economizer hours — when the outdoor air is already favorable and recovery would add unwanted heat — or where frost control or the energy code economizer provisions require the recovery to be bypassed. Bypass shall be controlled by the [[sync/building-automation-system]].
+
+```datasheet
+label: Energy Recovery Bypass
+type: radio
+options:
+ - "Provide recovery bypass damper (economizer-capable or code-required)"
+ - "No bypass (recovery active whenever the unit runs)"
+default: "Provide recovery bypass damper (economizer-capable or code-required)"
+```
+
+# Cooling and Dehumidification
+
+The cooling section of a DOAS does a different job than the cooling coil of a mixed-air unit: it is selected to drive the air to a low leaving dewpoint, which usually means cooling the air below the temperature the space actually wants. This is the core engineering of a DOAS. To reach a 50°F to 55°F leaving dewpoint at a humid design condition, the coil leaving dry-bulb must be at or below that dewpoint (the air leaves the coil at or near saturation), which is colder than a comfortable supply temperature. The air is then reheated to the desired supply temperature — but the moisture has already been removed and stays removed. AHRI 920 rates this behavior directly: its integrated seasonal moisture removal efficiency (ISMRE2, in pounds of moisture removed per kilowatt-hour) measures how efficiently the unit removes moisture across a range of conditions, and AHRI 920 testing is run to a 55°F leaving dewpoint reference.
+
+## Cooling Source
+
+The cooling source shall be selected to match the project's energy infrastructure and the unit type. Integrated DX (a packaged compressorized circuit within the unit) is the most common for standalone packaged DOAS because it makes "free" recovered reheat available from the condenser. A heat pump adds heating from the same circuit. A chilled water coil is used where a central chilled water plant exists and the DOAS is one of many loads on it; a chilled water DOAS must obtain its reheat from a separate source, since there is no condenser heat to recover.
+
+```datasheet
+label: Cooling Source (detail)
+type: radio
+options:
+ - "Integrated DX — single or multiple compressor stages"
+ - "Integrated DX with variable-capacity (variable-speed or digital) compressor"
+ - "Heat pump — reversible refrigerant circuit (cooling and heating)"
+ - "Chilled water coil — central plant"
+default: "Integrated DX with variable-capacity (variable-speed or digital) compressor"
+```
+
+Variable-capacity compressors are strongly preferred for DOAS because the latent load varies enormously across the year, and a single-stage compressor either dehumidifies fully or not at all. A variable-capacity circuit can hold the leaving dewpoint at part-load ventilation rates and at the many mild, humid hours when a fixed-stage unit would short-cycle and deliver wet air.
+
+```datasheet
+label: Cooling Coil Leaving Air Dewpoint (Design)
+type: range
+unit: °F
+options:
+ min: 40
+ max: 55
+ setpoints: [40, 45, 48, 50, 52, 55]
+default: 52
+```
+
+## Part-Load Dehumidification
+
+The DOAS shall hold the leaving dewpoint setpoint across the range of operating conditions, not only at the design hour. Many of the wettest hours of the year are mild — a rainy 70°F day at near-saturation carries a large latent load with almost no sensible load — and a unit that can only dehumidify at peak sensible conditions will deliver humid air during exactly those hours. The unit shall provide dehumidification down to the specified minimum turndown, by compressor staging or variable capacity, and the part-load performance shall be documented in the submittal.
+
+```datasheet
+label: Minimum Dehumidification Turndown
+type: select
+options:
+ - "Single stage — full capacity only (small units, mild climates)"
+ - "Two-stage — approximately 50% capacity at low stage"
+ - "Variable capacity — continuous modulation to approximately 25% capacity"
+default: "Variable capacity — continuous modulation to approximately 25% capacity"
+```
+
+## Reheat (Dehumidification Reheat)
+
+Reheat is not optional comfort tuning on a DOAS — it is the mechanism that makes low-dewpoint dehumidification possible without delivering uncomfortably cold air, and on a neutral-supply unit it is a continuous part of normal operation. The decision is where the reheat energy comes from. Recovered reheat — hot-gas (refrigerant) reheat that takes heat rejected by the unit's own condenser, a wraparound heat pipe or runaround coil that precools the entering air and reuses that captured heat to rewarm the leaving air, or a passive dehumidification wheel — is "free" in the sense that it spends no purchased energy on reheat. Purchased reheat (a hot water or electric coil) is simpler but spends energy heating air that was just cooled, which the energy code restricts. Recovered reheat shall be used wherever the unit type allows it; purchased reheat shall be limited to applications where no recovered source is available or where the energy code permits it.
+
+```datasheet
+label: Reheat Method (detail)
+type: radio
+options:
+ - "Hot-gas reheat — single-circuit condenser heat to a reheat coil (standard DX)"
+ - "Modulating hot-gas reheat — staged or valved for variable leaving-temperature control"
+ - "Wraparound heat pipe — passive, sealed refrigerant loop around the cooling coil"
+ - "Wraparound runaround coil — pumped glycol loop around the cooling coil"
+ - "Dehumidification (desiccant) wheel — passive sensible reheat from the process air"
+ - "Hot water reheat coil — purchased energy (where recovered reheat unavailable)"
+ - "Electric reheat coil — purchased energy (where recovered reheat unavailable)"
+default: "Modulating hot-gas reheat — staged or valved for variable leaving-temperature control"
+```
+
+A wraparound device (heat pipe or runaround coil) deserves note because it improves dehumidification while it reheats: by precooling the entering air before the cooling coil, it lets the cooling coil reach a lower dewpoint for the same compressor capacity, and it then uses that captured heat to reheat the leaving air — typically lifting the supply from roughly 48°F to roughly 55°F — with no purchased energy and no controls. Its limitation is that a passive wraparound is largely self-regulating and cannot independently set the supply temperature; where precise leaving-temperature control is needed, modulating hot-gas reheat or a controlled wraparound is required.
+
+```datasheet
+label: Reheat Leaving Air Temperature Setpoint
+type: range
+unit: °F
+options:
+ min: 55
+ max: 75
+ setpoints: [55, 60, 65, 68, 70, 72, 75]
+default: 70
+```
+
+# Heating
+
+In the heating season the DOAS shall temper the cold ventilation air so that it does not chill the spaces or the inlets of the parallel sensible system. With energy recovery active, much of the heating is recovered from the exhaust; the heating source supplies the remainder. For a neutral-supply unit, the heating section warms the air to near the space-neutral temperature; for a tempered-reset unit it may warm it further to offset part of the space heating load.
+
+```datasheet
+label: Heating Source (detail)
+type: select
+options:
+ - "Heat pump — integral reversible circuit"
+ - "Heat pump with auxiliary electric or gas backup for low ambient"
+ - "Indirect gas-fired furnace (stainless heat exchanger)"
+ - "Electric resistance coil"
+ - "Hot water coil — central plant"
+ - "None — tempering by energy recovery only"
+default: "Heat pump with auxiliary electric or gas backup for low ambient"
+```
+
+```datasheet
+label: Heating Supply Air Temperature Setpoint
+type: range
+unit: °F
+drawing_ref: true
+options:
+ min: 60
+ max: 95
+ setpoints: [60, 65, 68, 70, 75, 85, 95]
+default: 70
+```
+
+Heat-pump heating capacity falls as outdoor temperature falls, exactly when the heating load is greatest, so air-source heat-pump DOAS units in cold climates shall include auxiliary heat sized to carry the unit through the heating design condition and any heat-pump defrost cycles. Where a hot water coil is the heating source in a freezing climate, freeze protection shall be provided as specified under Casing, Fans, Coils, Filters.
+
+# Casing, Fans, Coils, Filters
+
+## Casing
+
+The casing shall be double-wall construction throughout, because a DOAS handles cold, dehumidified air on the supply side and cold outdoor air on the entering side, and condensation will form on any cold single-wall panel. Panel insulation R-value shall be appropriate for the climate; cold-climate and outdoor units warrant higher-R panels to prevent exterior condensation and limit conduction loss.
+
+```datasheet
+label: Casing Panel Construction
+type: radio
+options:
+ - "Double-wall, injected foam insulation (standard)"
+ - "Double-wall, injected foam with thermal break at panel edges (cold climate / high-humidity)"
+default: "Double-wall, injected foam insulation (standard)"
+```
+
+```datasheet
+label: Casing Panel Thermal Value (R-value)
+type: select
+unit: hr·ft²·°F/Btu
+options:
+ - "R-6 to R-8 (standard commercial)"
+ - "R-10 to R-13 (cold climate / outdoor DOAS)"
+default: "R-6 to R-8 (standard commercial)"
+```
+
+Outdoor and rooftop units shall be provided with a factory weatherproof casing: pitched or sloped top panels, weather hoods and drainable louvers (rated per AMCA 500-L) over the outdoor air intake and exhaust, bird screens, a drainable base rail, gasketed access doors with hold-open hardware, and corrosion-resistant exterior hardware. The exterior finish shall be a two-coat corrosion-inhibiting and UV-resistant system.
+
+```datasheet
+label: Outdoor Unit Weatherproofing
+type: checkbox
+options:
+ - "Sloped/pitched weather top panels"
+ - "Drainable intake/exhaust louvers (AMCA 500-L) with bird screen"
+ - "Drainable base rail and roof curb seal"
+ - "Gasketed access doors with hold-open and lockable latches"
+ - "Two-coat corrosion-inhibiting, UV-resistant exterior finish"
+default: "Sloped/pitched weather top panels"
+```
+
+## Fans
+
+Supply and exhaust fans shall be direct-drive plenum (plug) fans driven by electronically commutated (ECM) motors or by variable-frequency-driven premium-efficiency motors, so that airflow can be held constant as filters and the recovery device load, and so that fan power complies with ASHRAE 90.1. Fan and airflow performance shall be rated per AHRI 430 / AMCA 210. Fans shall be selected at the design airflow and external static pressure with capacity to maintain design airflow at the loaded-filter and frosted-recovery condition.
+
+```datasheet
+label: Fan Motor and Speed Control
+type: radio
+options:
+ - "ECM (electronically commutated) motor — integral variable speed (standard for smaller units)"
+ - "Premium-efficiency motor with variable frequency drive (larger units)"
+default: "ECM (electronically commutated) motor — integral variable speed (standard for smaller units)"
+```
+
+## Coils
+
+Cooling, reheat, and heating coils shall be rated and certified per AHRI 410, with tube and fin materials suited to the airstream. Because the cooling coil runs wet continuously and the entire airstream is outdoor air, coastal and corrosive-environment units shall use corrosion-resistant fin treatment.
+
+```datasheet
+label: Cooling Coil Fin Treatment
+type: radio
+options:
+ - "Aluminum fins (standard inland environment)"
+ - "Coated aluminum fins (coastal/corrosive — within ~3 mi of saltwater or industrial air)"
+default: "Aluminum fins (standard inland environment)"
+```
+
+Cooling coil face velocity shall be selected to limit moisture carryover off a continuously wet coil; a face velocity at or below 500 ft³/min per ft² (cfm/ft²) of coil face is recommended for DOAS, lower than a comparable mixed-air unit, because the DOAS coil is always operating wet at design.
+
+```datasheet
+label: Cooling Coil Face Velocity (Maximum)
+type: range
+unit: fpm
+options:
+ min: 350
+ max: 550
+ setpoints: [350, 400, 450, 500, 550]
+default: 450
+```
+
+## Drain Pan and Condensate
+
+A sloped, fully draining stainless steel drain pan shall be provided under the cooling coil and under any other condensing section. Because a DOAS coil runs wet continuously, standing water is both a Legionella risk and a corrosion risk; the pan shall fully drain and shall be Type 304 stainless steel minimum (Type 316 in coastal or chemical environments). A condensate trap with seal depth matched to the section's static pressure shall be provided so the trap is neither blown nor sucked dry.
+
+```datasheet
+label: Drain Pan Material
+type: radio
+options:
+ - "Type 304 stainless steel (standard)"
+ - "Type 316 stainless steel (coastal/chemical environment)"
+default: "Type 304 stainless steel (standard)"
+```
+
+## Hot Water Coil Freeze Protection
+
+Where a hot water heating or reheat coil is used in a freezing climate, freeze protection shall be provided, because the coil sees full design outdoor air with no warm return air to buffer it. Protection shall be a serpentine-element low-limit (freeze-stat) covering the coil face, glycol in the coil loop, or a face-and-bypass arrangement, as appropriate.
+
+```datasheet
+label: Hot Water Coil Freeze Protection
+type: select
+options:
+ - "Serpentine-element low-limit thermostat (full-face coverage)"
+ - "Glycol solution in the coil loop"
+ - "Not applicable (no hydronic coil, or non-freezing climate)"
+default: "Not applicable (no hydronic coil, or non-freezing climate)"
+```
+
+## Filtration
+
+Final filtration shall be MERV 13 for occupied-space ventilation air unless the application requires higher efficiency, with a pre-filter to extend final-filter life. Filter frames shall seal positively to prevent bypass, which would void the rated efficiency.
+
+```datasheet
+label: Pre-Filter MERV Rating
+type: select
+options:
+ - "MERV 7 — synthetic media panel pre-filter (standard)"
+ - "MERV 8 — pleated pre-filter"
+ - "None (single-stage filtration)"
+default: "MERV 7 — synthetic media panel pre-filter (standard)"
+```
+
+# Controls and BAS Integration
+
+The DOAS is a sequence machine: it must coordinate energy recovery, deep cooling, dehumidification, and reheat to hold a leaving dewpoint, and it must coordinate with the parallel sensible system so the two never undo each other's work. The unit shall be furnished with factory controls and a labeled terminal interface, and shall integrate with the [[sync/building-automation-system]]. Sequences should follow the intent of ASHRAE Guideline 36 where applicable.
+
+```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 IP (Ethernet)"
+```
+
+## Control of Dehumidification and Reheat
+
+The primary control loop shall sequence the cooling coil to maintain the leaving dewpoint (or leaving humidity ratio) setpoint, and shall sequence the reheat independently to maintain the supply dry-bulb setpoint. Holding these two loops independent is what lets the DOAS control humidity without coupling it to space temperature — the defining behavior of a decoupled-latent system.
+
+```datasheet
+label: Dehumidification Control Variable
+type: radio
+options:
+ - "Leaving air dewpoint sensor (direct dewpoint control)"
+ - "Leaving air relative humidity and temperature (computed humidity ratio)"
+default: "Leaving air dewpoint sensor (direct dewpoint control)"
+```
+
+## Supply Reset
+
+Supply air temperature and dewpoint may be reset by the BAS based on outdoor conditions, space humidity, or the load on the parallel sensible system, to save reheat energy when the full dehumidification capacity is not needed. Reset logic shall be coordinated with the [[sync/building-automation-system]].
+
+```datasheet
+label: Supply Air Reset
+type: select
+options:
+ - "Fixed leaving dewpoint and supply temperature setpoints"
+ - "Dewpoint reset on space humidity; fixed supply temperature"
+ - "Full reset of dewpoint and supply temperature by BAS"
+default: "Dewpoint reset on space humidity; fixed supply temperature"
+```
+
+## Interlock with Parallel Sensible System
+
+The DOAS and the parallel sensible system shall be interlocked through the BAS so that the parallel system does not satisfy space temperature in a way that drives space humidity up (overcooling that raises relative humidity), and so that the DOAS ventilation runs whenever the spaces are occupied. Occupancy scheduling, demand-controlled ventilation reset (where CO2 sensing is used), and the night/unoccupied mode shall be coordinated across both systems.
+
+## Minimum Control Points
+
+```datasheet
+label: Controls Points Package
+type: checkbox
+options:
+ - "Outdoor air temperature and humidity sensors"
+ - "Supply air temperature sensor"
+ - "Supply air dewpoint or humidity sensor"
+ - "Cooling coil leaving air temperature sensor"
+ - "Compressor / cooling capacity control output"
+ - "Reheat control output (hot-gas valve or coil)"
+ - "Heating control output"
+ - "Energy recovery drive / speed and bypass control"
+ - "Energy recovery frost-control status"
+ - "Supply and exhaust fan speed control and status"
+ - "Filter differential pressure switch or transmitter"
+ - "Outdoor and exhaust air damper actuators and end switches"
+ - "Smoke detector(s) per NFPA 90A"
+ - "Condensate overflow / drain-pan high-level switch"
+ - "Unit alarm summary to BAS"
+default: "Supply air dewpoint or humidity sensor"
+```
+
+# Testing
+
+## Factory Testing
+
+Each unit shall receive the manufacturer's standard production tests plus a functional run test confirming that the refrigeration or heat-pump circuit, fans, energy recovery drive, and the dehumidification-and-reheat sequence operate and that the unit produces the rated leaving dewpoint at the factory test condition. A drain-pan tightness test and an electrical continuity and insulation test shall be included. A factory test report shall be submitted at closeout.
+
+```datasheet
+label: Factory Test
+type: radio
+options:
+ - "Standard production test plus functional run test (certified report submitted)"
+ - "Witnessed factory test — provide 10 business days notice"
+default: "Standard production test plus functional run test (certified report submitted)"
+```
+
+## Field Testing and TAB
+
+After installation, the system shall be tested, adjusted, and balanced by an independent certified agency per [[sync/testing-adjusting-and-balancing]]. The TAB agent shall set and document the design outdoor (ventilation) airflow and the exhaust airflow through the recovery device, and shall confirm that the supply-to-exhaust airflow ratio is within the range the energy recovery device was rated for, since EATR and effectiveness are airflow-ratio dependent. Functional testing shall verify that the unit holds the leaving dewpoint setpoint, that reheat maintains the supply temperature setpoint, that energy recovery frost control operates, and that the interlock to the parallel sensible system behaves as designed.
+
+```datasheet
+label: Field Functional Performance Test
+type: checkbox
+options:
+ - "Ventilation and exhaust airflow set and documented (TAB)"
+ - "Leaving dewpoint setpoint held at test condition"
+ - "Reheat maintains supply temperature setpoint"
+ - "Energy recovery effectiveness / airflow ratio verified"
+ - "Frost-control sequence verified"
+ - "Parallel-system interlock and occupancy modes verified"
+default: "Ventilation and exhaust airflow set and documented (TAB)"
+```
+
+# Installation
+
+## Rigging and Mounting
+
+The unit shall be rigged and set per the manufacturer's instructions using furnished rigging points; cables shall not bear on casing panels. Rooftop units shall be set on a level, gasketed roof curb that matches the unit supply, exhaust, and intake openings; grade-mounted units shall be set on a level housekeeping pad. After setting, the unit shall be verified level so the drain pan slopes to drain. Vibration isolation shall be provided as required by the unit type and location.
+
+## Clearances
+
+Service clearances shall be maintained per the manufacturer's instructions for energy recovery wheel or core removal, coil pull, filter access, and compressor and control service, and for the airflow clearance at outdoor intakes and exhausts. Clearances shall be coordinated with [[drawing: the roof plan / mechanical equipment layout]].
+
+## Outdoor Air Intake Location
+
+The outdoor air intake shall be located to draw clean air and shall comply with the ASHRAE 62.1 separation distances from exhaust outlets, plumbing vents, cooling towers, loading docks, and other contaminant sources. The DOAS conditions 100% outdoor air, so a poorly located intake contaminates the entire ventilation supply. The intake and the unit's own exhaust discharge shall be separated so the exhaust is not short-circuited back into the intake. Intake and exhaust locations are [[drawing: as indicated on the roof plan and the mechanical site plan]].
+
+## Condensate
+
+The condensate drain shall be trapped with a seal depth matched to the unit static pressure, run to an approved point of disposal with continuous slope, and provided with a union for trap cleaning. Where the unit is in a freezing location, the condensate drain shall be protected from freezing.
+
+## Duct, Intake, and Exhaust Connections
+
+Supply and exhaust ductwork shall connect through flexible connectors and shall be independently supported so duct weight is not carried by the casing. Ductwork construction shall conform to [[sync/hvac-ductwork]], and supply ductwork carrying cold, dehumidified DOAS air shall be insulated and vapor-sealed per [[sync/mechanical-insulation]] to prevent external condensation.
+
+# Startup and Commissioning
+
+Startup shall be performed by a factory-trained representative of the manufacturer. The startup sequence shall verify refrigerant charge (DX and heat-pump units), fan rotation and airflow, energy recovery drive operation and purge (where provided), the dehumidification-and-reheat sequence holding the leaving dewpoint, the heating sequence, the frost-control sequence, and the reporting of all BAS points. TAB per [[sync/testing-adjusting-and-balancing]] and functional performance testing by the commissioning agent shall follow startup. Commissioning shall include a wet-condition test of dehumidification where the season permits, or a documented plan for deferred seasonal testing where it does not.
+
+```datasheet
+label: Startup and Commissioning Level
+type: select
+options:
+ - "Manufacturer startup with TAB verification"
+ - "Manufacturer startup, TAB, and functional performance testing by commissioning agent (standard)"
+ - "Manufacturer startup, TAB, FPT, and deferred seasonal (wet-condition) dehumidification test"
+default: "Manufacturer startup, TAB, and functional performance testing by commissioning agent (standard)"
+```
+
+# Warranty
+
+## Equipment Warranty
+
+The manufacturer shall warrant the complete unit against defects in materials and workmanship from the date of substantial completion.
+
+```datasheet
+label: Equipment Warranty Period
+type: select
+options:
+ - "1 year parts and labor"
+ - "2 years parts and labor"
+ - "5 years parts, 1 year labor"
+default: "1 year parts and labor"
+```
+
+## Compressor Warranty
+
+The compressor(s) in DX and heat-pump units shall carry an extended warranty, because compressor replacement is the most consequential failure on a packaged DOAS.
+
+```datasheet
+label: Compressor Warranty
+type: radio
+options:
+ - "Standard — 1 year same as equipment"
+ - "Extended — 5 years on compressor"
+default: "Extended — 5 years on compressor"
+```
+
+## Energy Recovery Component Warranty
+
+The energy recovery device — the wheel and its drive and seals, or the fixed-plate core, or the heat-pipe/runaround assembly — shall carry a warranty against defects and against loss of rated effectiveness from a defect.
+
+```datasheet
+label: Energy Recovery Component Warranty
+type: radio
+options:
+ - "1 year (minimum)"
+ - "5 years on energy recovery wheel/core and drive"
+default: "5 years on energy recovery wheel/core and drive"
+```
+
+## Installation Warranty
+
+The Contractor shall warrant the installation workmanship, including the curb and intake/exhaust connections, condensate, flexible connections, and controls terminations, 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 type and MERV)"
+ - "One energy recovery wheel drive belt (rotary units)"
+ - "One set of energy recovery wheel seals (rotary units)"
+ - "One set of access door gaskets"
+ - "Set of spare fuses for all fuse types installed"
+default: "One complete set of spare filters (each type and MERV)"
+```
+
+Spare filters shall be stored in sealed manufacturer's packaging labeled with the unit designation, MERV rating, and the installation date of the set in service. The O&M manual shall include the filter change schedule, the energy recovery maintenance schedule (wheel seal and belt inspection, or fixed-plate core cleaning), and the condensate trap cleaning procedure.