1 Scope
NOTE This standard covers the materials, construction, performance, testing, installation, and commissioning of factory-fabricated fan-coil units that recirculate room air across a cooling and heating coil to condition an individual zone. (1.1)
NOTE Equipment covered includes 2-pipe and 4-pipe hydronic units with chilled water and hot water coils, units with electric heating coils, and units with direct-expansion (DX) refrigerant coils, in vertical and horizontal arrangements, in concealed (ducted) and exposed (cabinet) configurations, and in floor-mounted, ceiling-mounted, recessed, and stacked high-rise riser types. (1.2)
NOTE A fan-coil unit is the point at which the building's central water or refrigerant plant meets each thermal zone; its selection determines zone comfort, sound level in the occupied space, and the energy the fan consumes over the life of the building. (1.3)
NOTE A fan-coil unit recirculates room air and, unless equipped with a dedicated outdoor-air connection, provides no ventilation air; where the served space requires outdoor air, ventilation shall be furnished by separate means and this standard does not by itself satisfy any ASHRAE 62.1 ventilation-rate requirement. (1.4)
1.5 Units covered by this standard shall be rated in accordance with ANSI/AHRI 440 (I-P) so that cooling capacity, heating capacity, airflow, and fan power can be compared on a consistent basis across manufacturers.
1.6 Coordinate chilled water and hot water piping connections, isolation, and balancing with Hydronic Piping. 1.8 Coordinate post-installation airflow setting and waterside balancing with Testing Adjusting And Balancing. 1.9 Coordinate ducted supply and return connections for concealed units with Hvac Ductwork. 2 Referenced Standards
2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each standard below unless a specific edition is referenced by the contract documents or by the local building code.
2.2 Where conflicts exist between referenced standards, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
2.3 Referenced standards list
| Standard |
Title |
| ANSI/AHRI 440 (I-P) |
Performance Rating of Fan-Coil Units |
| ANSI/AHRI 441 (SI) |
Performance Rating of Fan-Coil Units (SI units) |
| ANSI/AHRI 410 |
Performance Rating of Forced-Circulation Air-Cooling and Air-Heating Coils |
| ANSI/ASHRAE 62.1 |
Ventilation and Acceptable Indoor Air Quality |
| ANSI/ASHRAE/IES 90.1 |
Energy Standard for Buildings Except Low-Rise Residential Buildings |
| ANSI/ASHRAE 52.2 |
Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size (MERV) |
| NFPA 90A |
Standard for the Installation of Air-Conditioning and Ventilating Systems |
| NFPA 70 (NEC) |
National Electrical Code (branch circuits, disconnects, Article 424 fixed electric space-heating) |
| UL 1995 |
Heating and Cooling Equipment (where accepted by the AHJ for legacy listings) |
| UL 60335-2-40 |
Safety of Household and Similar Electrical Appliances — Particular Requirements for Electrically Operated Heat Pumps, Air-Conditioners, and Dehumidifiers |
| AMCA 210 |
Laboratory Methods of Testing Fans for Certified Aerodynamic Performance Rating |
| AMCA 300 |
Reverberant Room Method for Sound Testing of Fans |
| ASTM A653 |
Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) by the Hot-Dip Process |
| ASHRAE 15 |
Safety Standard for Refrigeration Systems (DX units) |
| ASHRAE Handbooks |
HVAC Systems and Equipment; Applications |
3 Submittals
3.1 Action Submittals
3.1.1 The Contractor shall submit the following for the Engineer's review and return prior to fabrication or procurement of the fan-coil units.
3.1.2 No fabrication or shipment shall proceed until the associated submittal has been reviewed and returned with no outstanding engineering questions.
3.1.3 Submit the following action submittals:
- Product data and configuration schedule for each unit tag, including arrangement (vertical or horizontal), cabinet type (concealed or exposed), pipe configuration (2-pipe or 4-pipe or DX), nominal airflow, cooling and heating capacity, coil rows, fan and motor type, filter type and MERV rating, electrical characteristics, and weight
- AHRI 440 certified performance data for each unit configuration, including total and sensible cooling capacity, heating capacity, airflow at the selected fan speed, external static pressure, and fan power input
- Coil capacity and selection data showing entering and leaving air conditions, entering and leaving water temperatures and flow (hydronic) or refrigerant data (DX), and waterside pressure drop at design flow
- Sound power data per octave band developed by an AMCA-recognized method, at the selected fan speed and external static pressure
- Fan and motor data including motor type (ECM/EC or PSC), nameplate power, efficiency, and the available fan speeds or speed-control range
- Filter data including filter type, MERV rating per ASHRAE 52.2, and filter access arrangement
- Condensate management data including primary drain pan material, secondary (auxiliary) drain pan provision, condensate float switch, and condensate pump where provided
- Control valve and actuator data including valve type (2-way or 3-way), close-off rating, Cv, fail-safe position, and modulating signal type
- DDC controller data including communication protocol, hardwired input and output count, and supported control sequences
- Cabinet finish data including the finish system and available colors for exposed units
- Shop drawings showing each unit in plan and section with field connection points dimensioned (supply and return water, condensate, electrical, control wiring, ducted supply and return for concealed units), required service clearances, and filter and access-panel locations
☑ Product data and configuration schedule per tag
☐ AHRI 440 certified performance data
☐ Coil capacity and selection data
☐ Sound power data per octave band (AMCA method)
☐ Fan and motor data (ECM/EC or PSC)
☐ Filter data (type and MERV per ASHRAE 52.2)
☐ Condensate management data (pans, float switch, pump)
☐ Control valve and actuator data
☐ DDC controller data and BAS protocol
☐ Cabinet finish and color data (exposed units)
☐ Shop drawings with clearances and field connections
3.2 Closeout Submittals
3.2.1 At substantial completion the Contractor shall provide the following closeout submittals:
- Operation and maintenance (O&M) manuals including the manufacturer's installation, operation, and maintenance instructions; filter replacement schedule and part numbers; controller programming reference; and recommended preventive maintenance schedule
- As-built configuration drawings reflecting any field modifications to the submitted configuration
- Factory test reports for each unit configuration, including coil pressure-test certification
- Field commissioning records, including airflow verification at design fan speed, waterside flow balancing, condensate drainage verification, and BAS point verification for each unit
- Warranty documentation from the fan-coil unit manufacturer and from any separately warranted sub-supplier components (ECM motor, DDC controller, electric heater, condensate pump)
☑ Operation and maintenance manuals
☑ As-built configuration drawings
☑ Factory test reports for each unit configuration
☑ Field commissioning records
☑ Warranty documentation
4 Quality Assurance
4.1 Manufacturer Qualifications
4.1.1 Fan-coil units shall be the product of a single manufacturer with a minimum of ten years of continuous experience designing and producing factory-fabricated fan-coil units for commercial HVAC service.
4.1.2 The manufacturer shall maintain an ISO 9001 certified quality management system.
4.1.3 The manufacturer shall be capable of providing replacement parts and service support for a minimum of fifteen years after the date of manufacture.
4.2 AHRI 440 Certification
4.2.1 Each fan-coil unit configuration furnished on the project shall be rated under the AHRI Certification Program for Fan-Coil Units per ANSI/AHRI 440.
4.2.2 Published cooling capacity, sensible cooling capacity, heating capacity, airflow, fan power, and waterside pressure drop shall reflect AHRI-certified values.
4.2.3 The certification mark shall appear on the product data submitted with the unit schedule.
4.2.4 AHRI certification datasheet
● AHRI 440 certified — all unit configurations on project
○ AHRI 440 certified — manufacturer participates and configuration is within certified range
4.3 NRTL Listing
4.3.1 Fan-coil units containing electric heating coils, fan motors, or electrically powered controls shall be listed and labeled by a Nationally Recognized Testing Laboratory (NRTL) to UL 60335-2-40, or to UL 1995 where the AHJ continues to accept legacy listings for equipment manufactured prior to the transition date.
4.3.2 Units with electric heating coils shall additionally comply with NFPA 70 Article 424 for fixed electric space-heating equipment.
4.3.3 Listed assemblies shall bear the NRTL label affixed to the cabinet in a visible location.
4.4 Pre-Installation Conference
4.4.1 Before installation of fan-coil units begins, the Contractor shall hold a pre-installation conference attended by the mechanical sub-contractor, the controls sub-contractor, the electrical sub-contractor, and the testing and balancing agent.
4.4.2 The pre-installation conference agenda shall include unit access and service-clearance requirements, condensate routing and slope coordination, piping connection sequencing, and the schedule for airflow setting and waterside balancing.
5 Environmental and Service Conditions
5.1 Fan-coil units shall be selected and rated for the conditions of the space they serve and for the entering water or refrigerant conditions of the plant they are connected to.
5.2 The unit shall deliver its scheduled cooling and heating capacity at the design entering air conditions, design entering water temperature and flow (or refrigerant condition for DX units), and the selected fan speed.
5.3 Entering air and water conditions
5.3.1 Design conditions shall be taken from the project basis-of-design and the unit schedule.
NOTE Cooling capacity shall be confirmed at the actual entering air wet-bulb temperature because sensible and latent split varies with entering humidity. (5.3.2)
NOTE AHRI 440 rates cooling at 80 °F dry-bulb and 67 °F wet-bulb entering air with 45 °F entering water; capacity at other conditions shall be confirmed against the manufacturer's selection program. (5.3.3)
5.4 Installation Location
5.4.1 Fan-coil units shall be suitable for continuous operation in indoor conditioned or semiconditioned spaces and shall not be installed outdoors or in any location subject to driving rain, condensation on the cabinet exterior, or freezing temperatures.
5.4.2 Units serving below-grade, garage, or other locations subject to elevated humidity or low ambient temperature shall be reviewed with the manufacturer for cabinet, coil freeze-protection, and condensate provisions before ordering.
5.4.3 Installation location datasheet
Occupied space — exposed cabinet unit
Above accessible ceiling — concealed unit
Vertical riser / closet — stacked unit
Mechanical closet serving adjacent zone
6 Unit Type and Arrangement
NOTE Fan-coil unit selection is determined by the zone's heating and cooling requirements, the central plant type (hydronic or DX), the available installation space, and the acoustical and aesthetic requirements of the served space. (6.1)
NOTE This section establishes the physical type of unit for each tag. (6.2)
6.3 Cabinet Type
NOTE Concealed (ducted) units have an unfinished cabinet installed above a ceiling or in a closet and connect to supply and return ductwork; they are the standard selection where the unit is hidden from the occupied space. (6.3.1)
NOTE Exposed (cabinet) units have a finished decorative cabinet installed within the occupied space with integral supply and return grilles; they are used where no ceiling or chase is available to conceal the unit. (6.3.2)
6.3.3 Cabinet type datasheet
Concealed — ducted (above ceiling)
Concealed — ducted (vertical closet / riser)
Exposed — finished cabinet, floor-mounted
Exposed — finished cabinet, ceiling-mounted
Recessed — built into ceiling or wall pocket
Per drawings
6.4 Arrangement
NOTE Vertical units stand upright with airflow discharged upward and are typically floor-mounted along a perimeter wall or in a riser closet. (6.4.1)
NOTE Horizontal units lie flat with airflow discharged horizontally and are typically suspended above a ceiling. (6.4.2)
6.4.3 Unit arrangement datasheet
● Horizontal (suspended, ceiling)
○ Vertical (floor-mounted or riser)
Per drawings
6.5 Stacked High-Rise Riser Type
6.5.1 Stacked vertical fan-coil units integrate the chilled water, hot water, and condensate risers within the unit chassis so that units stack floor-to-floor and the risers are made up unit-to-unit rather than run separately.
NOTE Stacked units are used in high-rise multifamily and hotel construction to minimize floor-to-floor riser coordination and to allow a single trade to set the unit and the riser together. (6.5.2)
6.5.3 Where stacked units are specified, the riser pipe sizes, insulation, and the floor penetration firestop detail shall be coordinated with Hydronic Piping. 6.5.4 Stacked riser unit datasheet
● Not stacked — independent unit with field-run piping
○ Stacked unit with integral risers (high-rise multifamily / hotel)
7 Coil Configuration
7.1 Pipe Configuration
NOTE A 2-pipe hydronic unit has a single coil supplied by one set of pipes that carries either chilled water or hot water depending on the seasonal changeover mode, and cannot cool and heat simultaneously. (7.1.1)
NOTE A 4-pipe hydronic unit has separate cooling and heating coils each served by its own supply and return pipes and valve, allowing the unit to cool or heat at any time independent of a building changeover mode. (7.1.2)
NOTE A DX unit uses a direct-expansion refrigerant coil connected to a remote condensing unit or refrigerant plant in place of a chilled water coil. (7.1.3)
NOTE A 2-pipe unit cannot provide heating during the cooling season changeover and is suitable only where the building operates in a single mode at a time; 4-pipe units are required where simultaneous heating and cooling across zones is needed, such as perimeter and interior zones with opposite loads. (7.1.4)
7.1.5 Pipe configuration datasheet
2-pipe — single hydronic coil (changeover chilled/hot water)
2-pipe with supplemental electric heat
4-pipe — separate hydronic chilled water and hot water coils
DX cooling coil with hot water heating coil
DX cooling coil with electric heating coil
DX cooling only
Per drawings
7.2 Heating Source
NOTE Hot water heating is the standard selection where a central hot water plant is provided; it offers high turndown, low operating cost, and quiet operation. (7.2.1)
NOTE Electric heating is used where no central hot water plant is provided or where running hot water piping to the zone is not cost-effective. (7.2.2)
7.2.3 ASHRAE 90.1 limits the use of new electric resistance heating in many building types and climate zones; verify code compliance before specifying electric heat as the default for the building.
7.2.4 Heating source datasheet
Hot water coil (hydronic)
Electric resistance heating coil
None (cooling only)
8.1 Nominal Airflow
NOTE Nominal airflow defines the unit's rated air delivery at the design fan speed against the design external static pressure. (8.1.1)
8.1.2 Airflow shall be selected so that the unit delivers its scheduled total and sensible cooling capacity at the design entering air and water conditions without exceeding the sound limit for the served space.
8.1.3 Nominal airflow datasheet
8.2 External Static Pressure
8.2.1 Concealed (ducted) units shall be selected against the external static pressure imposed by the connected supply and return ductwork, grilles, and any field-applied filter, so that the unit delivers design airflow at the selected fan speed.
8.2.2 Exposed cabinet units with integral grilles operate at minimal external static pressure and shall be selected at their free-discharge or low-static rating.
NOTE Selecting a ducted unit at the exposed-cabinet free-discharge airflow rather than against the actual duct external static pressure is a frequent cause of units that fail to deliver design airflow in the field. (8.2.3)
8.2.4 External static pressure datasheet
01
0.10.20.30.50.751
Default: 0.3 in. w.g.
Per drawings
8.3 Cooling Capacity
NOTE Total cooling capacity defines the unit's combined sensible and latent cooling output at the design entering air and entering water conditions. (8.3.1)
8.3.2 The unit shall be selected so that sensible cooling capacity meets the zone sensible load and total cooling capacity meets the combined sensible and latent load at design conditions.
8.3.3 Cooling capacity datasheets
8.4 Heating Capacity
8.4.1 Heating capacity defines the unit's heating output at the design entering air temperature and the design hot water entering temperature and flow, or the electric heater kW rating.
8.4.2 Heating capacity shall meet the zone heating load at the design entering water temperature of the project hot water plant, which shall not be assumed to be a generic catalog rating.
8.4.3 Heating capacity datasheets
NOTE Modern building hot water plants increasingly operate at 140 °F or lower entering water temperature to allow condensing boiler operation and heat pump heat recovery; a coil sized for 180 °F entering water will not deliver design capacity on a low-temperature plant. (8.4.4)
8.5 Coil Rows
8.5.1 Coil row count shall be selected to deliver the scheduled coil capacity at the design entering air, entering water temperature, and airflow.
NOTE Higher row counts deliver more capacity per unit face area at a lower entering water temperature but increase airside pressure drop and fan power. (8.5.2)
8.5.3 Coil rows datasheet
○ 2 rows (interior / low latent load)
● 3 rows (standard)
○ 4 rows (high latent load or elevated entering water temperature)
● 1 row (low capacity / high entering water temperature)
○ 2 rows (standard)
9 Fan and Motor
9.1 Fan Construction
9.1.1 Fans shall be forward-curved centrifugal blowers, statically and dynamically balanced, mounted on the motor shaft or on a resilient-mounted fan deck to limit vibration transmission to the cabinet.
9.1.2 Fan performance shall be developed by a method consistent with AMCA 210 and sound by a method consistent with AMCA 300.
9.2 Fan Motor Type
9.2.1 Electronically commutated motors (ECM/EC) shall be the standard fan motor selection for new construction.
NOTE ECM motors provide variable-speed control through a 0-10 V or PWM signal, achieve substantially higher efficiency than PSC motors across the operating range, and allow the airflow to be trimmed at commissioning without changing taps or pulleys. (9.2.2)
9.2.3 PSC (permanent split capacitor) motors are acceptable only where the contract documents specifically permit, and only with stepped speed control by tap selection.
NOTE ASHRAE 90.1 fan-power and motor-efficiency provisions increasingly favor or require ECM motors for terminal equipment; verify the applicable code requirement before defaulting to PSC. (9.2.4)
9.2.5 Fan motor datasheet
● ECM / EC — electronically commutated (variable speed, high efficiency) — standard
○ PSC — permanent split capacitor (multi-speed tap control, lower efficiency)
9.3 Fan Speed Control
9.3.1 ECM units shall provide continuously variable fan speed control commanded by the unit controller over the unit's operating range.
9.3.2 PSC units shall provide a minimum of three discrete fan speeds (low, medium, high) selectable at the unit and, where indicated, by the zone control.
9.3.3 Fan speed control datasheet
Variable speed — continuous (ECM, 0-10 V or PWM)
Three-speed tap selection (low / medium / high)
Single speed
10 Coils and Piping Connections
10.1 Coil Construction
10.1.1 Coils shall have seamless copper tubes mechanically expanded into aluminum or copper plate fins.
10.1.2 Hydronic coils shall be factory-pressure-tested to not less than 300 psig before shipment, and DX coils shall be factory-leak-tested and shipped with a holding charge of dry nitrogen.
10.1.3 Coil connection hand (left or right) shall be coordinated with the piping layout so that supply and return stub-outs face the piping chase.
10.1.4 Coil connection hand datasheet
● Left-hand connections (facing airflow discharge)
○ Right-hand connections (facing airflow discharge)
Per drawings
10.2 Control Valve Package
10.2.1 Each hydronic coil shall be served by a control valve sized for the coil flow and the available differential pressure.
NOTE Two-way modulating valves are the preferred selection on variable-flow hydronic distribution because they allow the central pumps to reduce flow at part load; three-way valves are used only on constant-flow systems where coil flow must be maintained regardless of valve position. (10.2.2)
NOTE Pressure-independent control valves (PICVs) maintain the commanded coil flow regardless of differential pressure variations across the building and are preferred where differential pressure varies widely between the nearest and most remote units. (10.2.3)
NOTE Low close-off leakage shall be coordinated with the valve actuator selection so that a closed valve does not allow chilled water through an idle coil, which produces unwanted condensation on the cabinet and coil. (10.2.4)
10.2.5 Control valve datasheets
Two-way modulating valve (variable-flow distribution)
Pressure-independent control valve (PICV) — variable flow
Three-way modulating valve (constant-flow distribution only)
Two-position (on-off) valve
● Fail closed
○ Fail open to heating (freeze protection on perimeter zones)
○ Fail in last position
10.3 Coil Freeze Protection
10.3.1 Hydronic coils serving zones with outdoor-air exposure or located in spaces subject to freezing shall be protected against coil freeze-up by a means appropriate to the installation, such as a freezestat that maintains minimum flow, fail-open heating valves, or a glycol solution where the plant permits.
NOTE A chilled or hot water coil exposed to subfreezing air with stagnant water will burst; freeze protection shall be confirmed for every unit with any path to freezing air before the coil is allowed to remain wet through winter. (10.3.2)
11 Filters
11.1 Filter Type and Rating
11.1.1 Each fan-coil unit shall include a return-air filter located so that all air entering the coil passes through the filter.
11.1.2 Filter efficiency shall be rated per ASHRAE 52.2 and expressed as a MERV value.
NOTE A 1-inch throwaway filter (MERV 1 to MERV 4) is the lowest acceptable selection and protects the coil from lint only; MERV 8 is the typical selection for general commercial service; MERV 13 is selected where improved indoor air quality is required and the unit fan and casing can accommodate the added pressure drop. (11.1.3)
NOTE Selecting a high-MERV filter without confirming that the unit fan can deliver design airflow against the added filter pressure drop is a common cause of starved airflow and reduced capacity. (11.1.4)
11.1.5 Filter rating datasheet
MERV 4 (1 in. throwaway — coil protection only)
MERV 8 (standard commercial)
MERV 11 (improved)
MERV 13 (enhanced IAQ — confirm fan capacity)
11.2 Filter Access
11.2.1 The filter shall be accessible for replacement without removing the unit from its installed position and, for concealed units, through the ceiling access provided.
NOTE Filter access location shall be coordinated so that the filter can be changed from the occupied side or through an access panel and does not require entry into an adjacent tenant space. (11.2.2)
11.2.3 Filter access datasheet
○ Bottom / return-face access (exposed cabinet)
● Side access panel (concealed unit)
○ Ducted return — filter in return grille (field-furnished)
12 Condensate Management
12.1 Primary Drain Pan
12.1.1 Each unit with a cooling coil shall include a corrosion-resistant primary drain pan extending under the full coil and under the coil connections and valve package where condensation can form.
12.1.2 The primary drain pan shall be sloped to the drain connection so that it drains completely with no standing water, and a condensate trap shall be installed per the manufacturer's instructions to seal the pan against the unit's negative or positive cabinet pressure and to ensure drainage.
12.1.3 Primary drain pan material datasheet
○ Galvanized steel with corrosion-resistant coating
● Stainless steel
○ Molded polymer / composite
12.2 Secondary Drain Pan and Float Switch
12.2.1 Where a unit is installed above a finished ceiling or above any space where a condensate overflow would cause damage, the unit shall be provided with an auxiliary (secondary) drain pan under the unit, a condensate overflow float switch, or both.
12.2.2 The condensate float switch shall shut down the unit, close the cooling valve, or both on detection of a high condensate level so that the overflow is stopped before water reaches the finished space.
NOTE Condensate overflow onto finished construction is the single most common cause of water damage from fan-coil units and is preventable with a secondary pan and a float switch; the protection shall not be omitted on units over occupied or finished space. (12.2.3)
12.2.4 Condensate overflow protection datasheet
Primary drain pan only (units not over finished space)
Primary pan with condensate float switch (shutdown on high level)
Primary pan, secondary pan, and float switch (over finished space)
12.3 Condensate Drainage and Pump
12.3.1 Condensate shall drain by gravity to a piped condensate system sloped to a point of disposal where the installation geometry permits.
12.3.2 Where gravity drainage is not feasible because the drain point is above the unit pan, a condensate pump with an integral high-level safety switch shall be provided.
12.3.3 Condensate drainage method datasheet
● Gravity drain to piped condensate system
○ Condensate pump with integral high-level safety switch
13 Cabinet and Finish
13.1 Cabinet Construction
13.1.1 Unit cabinets shall be fabricated from galvanized steel sheet conforming to ASTM A653 of gauge sufficient to resist deflection and drumming at the design fan speed, with insulation on interior surfaces to limit thermal transmission and to attenuate fan noise.
13.1.2 Cabinet interior insulation shall have a flame-spread and smoke-developed index acceptable under NFPA 90A and shall be protected against erosion into the airstream at the design face velocity.
13.2 Exposed Cabinet Finish
13.2.1 Exposed cabinet units shall have a factory-applied finish on all surfaces visible in the occupied space, free of scratches and uniform in color.
13.2.2 Cabinet color shall be coordinated with the architectural finish schedule for units located in the occupied space.
13.2.3 Exposed cabinet finish datasheet
Factory baked-enamel — manufacturer standard white
Factory baked-enamel — custom color to match architecture
Not applicable — concealed unit (unfinished cabinet)
Per drawings
14 Controls and BAS Interface
14.1 DDC Controller
14.1.1 Each fan-coil unit shall be furnished with a factory-installed or factory-supplied direct digital control (DDC) controller capable of executing the project's zone control sequence.
14.1.2 The controller shall include sufficient hardwired inputs and outputs for the unit's fan speed control, cooling and heating valve outputs (or DX and electric heat outputs), zone temperature sensor, condensate float switch, and any optional inputs indicated in the BAS sequence.
14.1.3 DDC controller datasheets
BACnet MS/TP (RS-485) — most common for terminal-unit networks
BACnet IP (Ethernet)
Modbus RTU (RS-485)
Manufacturer-proprietary protocol with gateway to BACnet
☐ Fan speed output (0-10 V ECM)
☐ Fan low/medium/high stage outputs (PSC)
☐ Chilled water valve output (modulating)
☐ Hot water valve output (modulating)
☐ Electric heat stage outputs
☑ Zone temperature sensor input
☐ Condensate float switch input (safety shutdown)
☐ Occupancy / motion sensor input
☐ Window / balcony door contact input
☐ Discharge air temperature sensor input
14.2 Coordination with Building Automation System
14.2.1 The fan-coil unit controller shall be commissioned by the controls contractor on the project's BAS network per Building Automation System. 14.2.2 Controller addressing and network segmentation shall be coordinated before unit shipment so that the factory-applied address and unit tag are consistent with the BAS database.
14.3 Zone Sensor
14.3.1 Each zone served shall be provided with a wall-mounted zone temperature sensor.
14.3.2 Where the project zoning includes occupant-adjustable setpoints, the wall sensor shall include a setpoint adjustment within a defined deadband relative to the system setpoint.
14.3.3 Zone sensor datasheet
Temperature only — no occupant adjustment
Temperature with limited setpoint adjustment (±2 °F)
Temperature with setpoint adjustment and fan-speed selection
Temperature with humidity (multi-function room sensor)
15 Electrical
15.1 Each fan-coil unit shall be connected to a branch circuit sized and protected per NFPA 70 using the minimum circuit ampacity (MCA) and maximum overcurrent protection (MOCP) marked on the unit nameplate.
15.2 A disconnecting means shall be provided within sight of each unit, or a lockable means shall be provided at the branch panelboard where permitted by the NEC.
15.3 Units with electric heating coils shall comply with NFPA 70 Article 424, shall include integral over-temperature protection, and shall include an airflow proving interlock that disables the heater when airflow falls below the manufacturer's minimum.
15.4 Low-voltage control wiring shall be Class 2 cable routed separately from line-voltage power wiring as required by the NEC, and plenum-rated cable shall be used in air-handling plenums.
15.5 Unit electrical service datasheet
120V / 1-phase
208V / 1-phase
240V / 1-phase
277V / 1-phase
208V / 3-phase (large units with electric heat)
Per drawings
16 Installation
16.1 Service Clearances
16.1.1 Before fabricating ceiling layouts and ductwork, the Contractor shall verify that each fan-coil unit can be installed with the manufacturer's required service clearances for fan and motor service, coil and valve access, filter replacement, and condensate trap and pan cleaning.
16.1.2 Where ceiling-tile access is not sufficient for a concealed unit, an access door shall be coordinated with the architectural finish schedule.
16.2 Mounting and Support
16.2.1 Horizontal units shall be suspended from structure using all-thread rod and the manufacturer's integral mounting provisions, and shall not be supported by the connected ductwork or piping.
16.2.2 Suspended units shall be installed level in the direction of condensate flow, or pitched toward the drain connection as the manufacturer requires, so that the primary drain pan drains completely.
16.2.3 Vertical and stacked units shall be set plumb and anchored to the floor or wall as the manufacturer requires.
NOTE A unit hung out of level so that the pan does not drain is a recurring cause of standing condensate, microbial growth, and overflow; pan slope shall be verified at installation. (16.2.4)
16.3 Piping Connections
16.3.1 Chilled water and hot water supply and return piping to coils shall comply with Hydronic Piping. 16.3.2 Each coil shall be served by a piping arrangement including an upstream isolation valve, a balancing or pressure-independent control valve, a strainer, an air vent at the high point, and a drain at the low point.
16.3.3 Piping shall be supported independently of the fan-coil unit and arranged to permit coil and valve removal without dismantling the connected piping.
16.3.4 Chilled water piping and valves within the conditioned space shall be insulated with a continuous vapor-tight insulation so that condensation does not form on cold piping, and the insulation shall not be omitted at the unit connection.
16.3.5 DX refrigerant connections shall be made per Hvac Ductwork coordination and the refrigerant-piping requirements of the matched condensing unit. 16.4 Condensate Piping
16.4.1 Condensate drain piping shall be run with a trap at the unit and sloped continuously to the point of disposal.
16.4.2 Condensate piping in the conditioned space shall be insulated where surface condensation would drip onto finished construction.
NOTE The condensate trap depth shall be coordinated with the unit cabinet static pressure so that the trap holds a seal and the pan drains under operating conditions. (16.4.3)
16.5 Ducted Connections (Concealed Units)
16.5.1 Concealed units shall connect to supply and return ductwork per Hvac Ductwork with a flexible connector at the unit to limit vibration and fan-noise transmission into the duct. 16.5.2 Where a ducted return is used, the return filter location shall be confirmed so that the unit coil remains protected by a filter.
17 Testing and Balancing
17.1 Airflow Setting
17.1.1 The testing, adjusting, and balancing agent shall set and verify the airflow at each unit at the design fan speed per Testing Adjusting And Balancing. 17.1.2 For ECM units the fan output shall be trimmed to deliver design airflow against the actual installed external static pressure; for PSC units the appropriate speed tap shall be selected.
17.2 Waterside Balancing
NOTE Where pressure-independent control valves are used, the design flow limit shall be confirmed at the valve rather than set with a separate balancing valve. (17.2.2)
17.3 Condensate and Functional Verification
17.3.1 The Contractor shall verify that each unit's primary pan drains completely with no standing water and that the condensate float switch shuts the unit down on a simulated high condensate level.
17.3.2 The full zone control sequence shall be demonstrated, including cooling and heating valve operation, fan speed response, changeover (2-pipe units), electric heat airflow interlock where applicable, and BAS reporting of all hardwired points.
18 Delivery, Storage, and Handling
18.1 Fan-coil units shall be delivered to the project site in original factory packaging with coil connections capped and supply and return openings sealed against construction dust.
18.2 Units shall be stored indoors in a clean, dry, conditioned space and shall not be stored on bare concrete, in standing water, or in any space subject to freezing or to roof leaks.
18.3 Hydronic coils on stored units shall be protected from freezing; where storage temperature can fall below 35 °F, coils shall be drained, blown out with compressed air, and tagged as drained, with a corresponding note on the unit schedule so that the coils are refilled and vented before startup.
18.4 DX units shall retain their factory nitrogen holding charge until connected, and any unit found with a lost holding charge shall be leak-tested before refrigerant connection.
19 Warranty
19.1 Equipment Warranty
19.1.1 The fan-coil unit manufacturer shall warrant the equipment against defects in materials and workmanship for the period specified below, beginning from the date of substantial completion.
19.1.2 The equipment warranty shall cover the cabinet, coil, fan and motor, drain pan, valve and actuator, controller, and all factory-installed components.
19.1.3 Equipment warranty period datasheet
1 year parts and labor from substantial completion (minimum)
2 years parts and labor from substantial completion
5 years parts, 1 year labor
19.2 ECM Motor and Coil Extended Warranty
19.2.1 ECM fan motors and hydronic coils shall carry an extended warranty consistent with industry practice for these components.
19.2.2 ECM motor and coil extended warranty datasheets
○ Standard — 1 year, same as equipment warranty
● Extended — 5 years on ECM motor and controller
1 year (minimum)
5 years against leakage in tube and fin assembly
19.3 Installation Warranty
19.3.1 The Contractor shall warrant the installation workmanship — including mounting, duct and piping connections, condensate piping and trap, electrical connections, control wiring, insulation, and labeling — for one year from the date of substantial completion.
19.3.2 The Contractor shall maintain access to all installed units during the warranty period by keeping access doors and ceiling tiles clear of permanent obstructions.
20 Spare Parts
NOTE The following spare parts datasheet establishes the spares to be delivered at substantial completion. (20.1)
☑ Spare filters — one full set per installed unit
☐ Spare fan motor — one per motor size and type
☐ Spare control valve actuator — one per valve size
☐ Spare DDC controller — one per controller model
☐ Spare condensate float switch — one per model
☐ Spare zone temperature sensor — quantity 5% of installed sensors
20.2 Spare parts shall be delivered to the Owner in the manufacturer's original packaging, each part tagged with the unit model number, part number, and date of delivery.
20.3 The O&M manual shall include a spare-parts inventory list with manufacturer part numbers and reorder information so that additional spares can be procured during the building's service life.