Installation: National Comfort Products NCPAH Series 24-A 36-A Apartment Air Handler Instruction Guide

Content

Overview

The NCPAH Series 24-A 36-A Apartment Air Handler is a vertical upflow indoor air-handling unit designed for apartment and multi-family HVAC installations. It can be installed in a closet, utility room, alcove, or on a wall, and supports both air-conditioning and heat-pump systems.

This air handler uses a direct-drive blower with a constant-torque ECM motor, an internally installed R-410A thermal expansion valve, and optional electric resistance heat. Installation, wiring, refrigerant work, and service should be completed by qualified HVAC personnel in accordance with applicable national, state, and local codes.

Specifications

Models: NCPAH-24-A and NCPAH-36-A.
Electrical supply: 208/230 VAC, single phase.
Installation position: Vertical upflow only.
Return-air options: Front return or bottom return.
Refrigerant metering: Factory-installed, non-bleed R-410A TXV.
Electric heat options: 5 kW, 7.5 kW, and 10 kW single-phase kits.
Drain connections: Primary and auxiliary 3/4-inch NPT female connections.
Filter size for Model 24: 16 x 20 x 1 inches.
Filter size for Model 36: 20 x 20 x 1 inches.
Model 24 dimensions: approximately 39 1/2 inches high, 22 inches wide, and 18 3/4 inches deep.
Model 36 dimensions: approximately 36 1/2 inches high, 20 1/2 inches wide, and 17 4/5 inches deep.
Approximate shipping weights: 99 pounds for Model 24 and 121 pounds for Model 36.
Mounting structures must support a minimum 150-pound load.

Detailed Description

The cabinet is fully insulated and includes factory-installed, corrosion-resistant drain pans for upflow operation. Mounting tabs and brackets support wall installation, while clearance holes allow the unit to be secured inside a suitable frame structure.

The blower uses a multi-speed direct-drive wheel and constant-torque ECM motor. Factory speed settings provide cooling and heating airflow, while additional motor taps can be selected when the duct system requires a different airflow. The motor also provides programmed fan-off delay operation.

The factory TXV is suitable for air-conditioning and heat-pump applications. Refrigerant line connections are positioned at the top of the cabinet, with a 3/4-inch vapor-line connection and a 3/8-inch liquid-line connection.

The air filter must be installed upstream of the evaporator coil. It protects the coil, blower, and internal components from dirt and helps maintain the intended airflow.

Safety

Disconnect all electrical power, including remote disconnects, before installation, adjustment, or service. Use appropriate lockout and tagout procedures.
More than one disconnect may be required to fully de-energize the equipment. Live electrical components may remain hazardous during testing and troubleshooting.
Ground the air handler permanently according to applicable electrical codes. Each supply circuit must be grounded when multiple circuits are used.
Wear gloves and eye protection when handling the cabinet or sheet metal. Edges and field-cut openings may be sharp.
Do not operate the unit during construction finishing work. Vapors and chlorides or fluorides from paint, adhesives, stains, cleaning products, and cement can combine with condensate and corrode the equipment.
Do not store gasoline, combustible materials, corrosive products, or flammable vapors near the air handler.
Do not install a unit with a non-ducted return in the same enclosed space as a fossil-fuel appliance. Hazardous combustion vapors could be circulated through the building.
Do not connect the return duct to a fireplace, stove, or other heat-producing appliance.
Fiberglass insulation may irritate the eyes, skin, and respiratory system. Avoid breathing dust, wear a suitable NIOSH-approved respirator during dusty work, and use protective clothing and eye protection.
Before operating the unit, verify that the blower motor support is tight and that the blower wheel is securely attached to the motor shaft.

Setup and Installation

Unpacking and Location

Inspect the air handler and shipping carton for damage before installation. Confirm the model, voltage, and any ordered accessory kits against the rating plate and shipment contents. Report damage, shortages, or discrepancies through the appropriate purchasing or delivery channel promptly.

Choose a central location with sufficient access for installation and service. The unit must be level from side to side and front to back so condensate can drain correctly. An uneven installation can cause water leakage and damage to drywall, flooring, framing, or other nearby structures.

Wall Mounting

Remove the lower wall-mounting bracket from the rear of the cabinet by removing its attaching screw. Discard that screw after removing the bracket.
Secure the bracket to a level structural wall using three field-supplied wood screws.
Do not fasten the bracket only to unsupported drywall. Screws must engage a structure capable of supporting at least 150 pounds.
Lift the air handler onto the installed wall bracket and secure the cabinet to the bracket.
Install the additional bottom support plate supplied in the lower portion of the shipping carton.

Frame Mounting

The cabinet has eight clearance holes, four on each side, for installation inside a properly constructed frame. Select a solid, level support structure and maintain the access space needed for service. Install the wood screws from inside the air handler cabinet rather than from outside, taking care not to damage the indoor coil.

Return-Air Configuration

The unit is shipped for a front-return arrangement. To convert it to bottom return, remove the cabinet cross brace and redirect the return-air opening through the bottom panel. Follow the cabinet opening and panel arrangement shown in the installation documentation, and seal joints to prevent air leakage.

Ductwork

Design the supply and return system for the unit's allowable external static pressure. Include the resistance of ductwork, grilles, filters, dampers, and accessories when estimating total system resistance. Undersized or poorly balanced ducts can reduce capacity, increase noise, and create drafts.

Follow NFPA 90A, NFPA 90B, applicable local requirements, and recognized duct-construction practices.
Insulate sheet-metal ducts routed through unconditioned spaces and cover the insulation with a vapor barrier.
Flexible duct must be selected and installed with straight-run and fitting pressure losses included in the design.
Attach the supply plenum to the supplied 3/4-inch duct flanges. An elbow installed close to the unit must not be smaller than the supply flange opening.
Do not drive screws into the return flange area containing power wiring. Sharp screw points or drills can damage internal wire insulation.
Secure duct connections with suitable fasteners and seal the duct-to-cabinet joints to limit leakage.

Condensate Drain

Both the primary and auxiliary 3/4-inch NPT drain connections must be trapped outside the cabinet and installed according to building codes. Use a drain line no smaller than the drain-pan connection.

Route condensate to an open drain or to an approved outdoor termination.
Pitch each drain downward away from the air handler at least 1/4 inch per foot.
Insulate the primary drain where surrounding conditions may reach dew-point temperatures and cause sweating.
If a cleanout tee is installed, seal or cap the standpipe.
Confirm that all drain joints are tight before operating the system.

Refrigerant Piping

Refrigerant connections are located at the top of the unit. Size and install external refrigerant lines according to the outdoor unit's requirements. If the air handler is recessed into a wall, pressure-test the piping before closing the wall. Protect the cabinet and rubber grommets from brazing heat.

Electric Heat

Optional 5 kW, 7.5 kW, and 10 kW electric heater kits are available. Heater installation and circuit protection must follow the applicable kit instructions, unit wiring diagram, nameplate data, and electrical codes. The factory-installed breaker associated with an electric heater protects internal wiring and does not replace overcurrent protection for the branch supply wiring.

Power Wiring

Use 75°C minimum copper supply conductors.
Connect power through the unit power terminal block.
Power wiring may enter through the right or left side using the provided 7/8-inch concentric knockouts.
Install a correctly sized branch-circuit disconnect within sight of and readily accessible to the air handler when required.
Use fuses or HACR-type circuit breakers sized according to the unit electrical data and local code.

Low-Voltage Controls and Thermostat

Use 18 AWG color-coded Class 2 control wire for typical runs. For runs longer than 100 feet, use 16 AWG wire. Keep low-voltage control wiring separate from line-voltage wiring unless the conductor and installation method meet the requirements for the higher voltage.

Use a thermostat suitable for a single-stage air-conditioning or heat-pump system with electric heat. Mount it on an interior wall approximately 4 to 5 feet above the floor, away from drafts, lighting, and other heat sources, in a location with representative air circulation.

Motor Speed Selection

Disconnect all power before changing motor speed taps. After selecting a tap, verify blower airflow and measure the temperature change across the evaporator coil to confirm that airflow is adequate.

Model 24 tap airflow at zero external static pressure ranges from approximately 581 to 884 CFM across taps 1 through 5.
Model 36 tap airflow at zero external static pressure ranges from approximately 936 to 1,309 CFM across taps 1 through 5.
Tap 4 is the factory setting for both models.
Cooling airflow should generally remain within approximately 300 to 450 CFM per ton, with 400 CFM per ton as a nominal target.

Operation

Cooling and Heat Pump Cooling

When the thermostat calls for cooling, the R-to-G circuit starts the indoor blower and the R-to-Y circuit signals the outdoor compressor contactor. On a heat-pump system, the R-to-O signal places the reversing valve in the cooling position.

Heat Pump Heating

During a heat call, R-to-G operates the indoor blower and R-to-Y starts the outdoor unit. The reversing valve is not energized in heating mode. If indoor temperature continues to fall, the thermostat can complete the R-to-W circuit to energize supplemental electric heat.

Electric-Heat-Only Operation

For electric heat without heat-pump operation, the thermostat completes R-to-G and R-to-W. The thermostat must be configured to operate the blower whenever the electric heater is energized.

Defrost Supplemental Heat

Supplemental indoor heat during a heat-pump defrost cycle can be provided by connecting the outdoor unit's X2 signal to the indoor unit's W1 terminal. This helps prevent cold air from being discharged indoors during defrost.

Performance

Actual airflow depends heavily on the duct system and the external static pressure imposed on the air handler. The published airflow values are based on a dry coil at 230 volts without an electric heater or filter installed. Airflow is substantially similar at 208 volts because the ECM motor maintains constant torque across its operating speeds.

For Model 24, airflow at the factory Tap 4 setting is approximately 796 CFM at zero static pressure and 538 CFM at 0.8 inches water column. For Model 36, Tap 4 provides approximately 1,122 CFM at zero static pressure and 836 CFM at 0.8 inches water column.

Return-air configuration has little effect on the listed airflow when the duct system is correctly designed. Supply diffusers and return grilles should be sized and positioned to provide quiet, balanced airflow throughout the apartment.

Checkout Procedure

Confirm that the wall, frame, or suspension support is secure and that no tools or loose material remain on or around the unit.
Verify that suction lines and fittings are properly insulated.
Secure and isolate refrigerant piping so it cannot rub against the cabinet or structure.
Check every electrical connection for proper tightness.
Confirm that all supply outlets are open and unobstructed.
Inspect primary and auxiliary drain lines for correct slope, traps, and tight joints.
Install the properly sized return-air filter.
Operate the complete system in each available mode, including supplemental electric heat, and verify proper response.
Complete refrigerant charge adjustment using the outdoor unit's required service procedure.

Cleaning and Maintenance

Inspect, clean, or replace the air filter at least monthly.
Replace and secure all access panels before returning the equipment to service.
Schedule professional maintenance at least annually.
Annual service should include inspection and testing of electrical and refrigerant components.
Clean the heat-transfer surfaces when dirt buildup reduces performance.
The blower motor is permanently lubricated for normal operating conditions.

Troubleshooting

Water Leaking From the Cabinet

Check that the air handler is level in both directions. Inspect the primary and auxiliary drain traps, confirm that drain lines slope away from the unit, and verify that the drain lines are not reduced below 3/4 inch or blocked.

Low Airflow or Excessive Noise

Inspect the filter, supply outlets, return grille, ductwork, and accessories for restrictions. Confirm that the selected motor tap matches the system requirements and that total external static pressure remains within the unit's operating range.

Blower Does Not Operate

Verify that all disconnects are on, the unit is properly grounded, the thermostat is sending the required G signal, and low-voltage wiring is separated and securely connected. Do not service live electrical components unless qualified to perform the work safely.

Insufficient Heating or Cooling

Check the filter, airflow, duct restrictions, thermostat configuration, refrigerant piping, and outdoor unit operation. A matched indoor and outdoor system is recommended for efficiency, performance, and reliability. Refrigerant charge adjustments must follow the outdoor unit service procedure.

Pros & Cons

Advantages

Supports wall, closet, utility-room, alcove, and frame-mount installations.
Offers front-return and bottom-return flexibility.
Uses a constant-torque ECM blower for adaptable airflow.
Includes primary and auxiliary condensate connections.
Works with air-conditioning and heat-pump applications.
Accepts several single-phase electric heat kit sizes.

Limitations

The cabinet is intended for vertical upflow installation only.
Professional installation is necessary for electrical, refrigerant, duct, and condensate work.
Performance depends strongly on correct duct design, airflow setup, filtration, and external static pressure.
Mounting support must safely carry at least 150 pounds and maintain a level installation.

Keep this NCPAH Series 24-A 36-A Apartment Air Handler guide with the equipment for future installation, service, and maintenance reference.

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Faqs

Where can the NCPAH Series 24-A or 36-A apartment air handler be installed?

The NCPAH 24-A and 36-A air handlers are designed for vertical upflow installation in a closet, utility room, alcove, basement, or similar indoor location. They can be wall mounted or secured inside a properly built frame. The supporting structure must be level and capable of carrying at least 150 pounds. Do not install the unit in a different airflow orientation, and provide the clearances needed for duct connections, service access, and safe maintenance.

How should the NCPAH apartment air handler be mounted to prevent condensate leaks?

Mount the air handler perfectly level from side to side and front to back so condensate flows correctly through the drain pan. For wall mounting, attach the supplied wall bracket to structural framing rather than unsupported drywall, using suitable wood screws. Install the additional lower support plate after hanging the unit. Frame-mounted installations must also use solid, level supports and fasteners installed from inside the cabinet without contacting the indoor coil.

Can the NCPAH 24-A or 36-A use a bottom return instead of a front return?

Yes. The air handler is supplied for a front return but can be converted to a bottom return. During conversion, remove the cabinet cross brace and install the appropriate front coil panel arrangement as shown in the installation instructions. Confirm that the return opening is fully sealed and that the duct system provides adequate airflow. The front and bottom return configurations use the same general airflow performance, provided the ductwork is correctly sized and installed.

What condensate drain requirements apply to the NCPAH Series air handler?

Both the primary and auxiliary condensate drains use 3/4-inch NPT connections. Each drain must be trapped outside the unit and routed according to applicable building codes. Keep the drain line at least the same size as the drain-pan connection, pitch it downward at least 1/4 inch per foot, and direct it to an open drain or outdoors. Insulate the primary drain where sweating may occur, and check every joint for leaks before operation.

What type of electrical wiring and grounding does the NCPAH 24-A or 36-A require?

The NCPAH Series operates on 208/230-volt, single-phase power, but the installer must verify the exact rating plate and wiring diagram before connection. Use 75°C minimum copper supply conductors, correctly sized branch-circuit protection, and a readily accessible disconnect when required. Permanently ground the cabinet using the provided grounding lug or code-compliant metal conduit. Multiple supply circuits require grounding for each circuit, and all power must be disconnected before servicing.

How should the thermostat be wired and positioned for the NCPAH air handler?

Use a compatible single-stage heating and cooling thermostat for air conditioning or heat-pump operation with electric heat. Install it on an interior wall approximately 4 to 5 feet above the floor, away from drafts, lights, and other heat sources. Use color-coded 18 AWG low-voltage wiring; runs longer than 100 feet should use 16 AWG. Keep thermostat wiring separate from high-voltage power wiring unless properly rated conductors and code-approved methods are used.

What should be checked if the NCPAH air handler has weak airflow or excessive noise?

Start by checking that the return filter is installed correctly and is not clogged. Inspect supply and return grilles for restrictions, confirm that ductwork is properly sized, and make sure flexible ducts are not sharply bent or crushed. The NCPAH 24-A uses a 16-by-20-by-1-inch filter, while the 36-A uses a 20-by-20-by-1-inch filter. If airflow remains inadequate, a qualified technician should verify the motor speed tap and external static pressure.

What routine maintenance does the NCPAH Series 24-A or 36-A need?

Inspect, clean, or replace the return air filter at least monthly, using the correct size for the model. Keep supply outlets open and unrestricted, and check condensate drain joints for secure connections and proper flow. During annual professional service, the electrical and refrigerant components should be inspected and the indoor heat-transfer surface cleaned. The blower motor is permanently lubricated under normal conditions, so additional routine lubrication is not normally required.