Lennox Merit CBX25UH Series Air Handler Installation Instructions

Table of Contents

• Shipping and Packing List
• CBX25UH Series Units
• Requirements
• Installation Clearances
• Installation
• Condensate Drain
• Duct System and Filters
• Connecting Refrigerant Lines
• Sealing the Unit
• Electrical Connections
• Airflow - Cooling Blower Speed
• Check-Out Procedures
• Operation
• Maintenance
• Cabinet Insulation

Shipping and Packing List

Package 1 of 1 contains the following:

• 1 - Assembled air handler unit for upflow or horizontal air discharge application (includes upflow and horizontal drain pans and pre-installed air filter).

Check equipment for shipping damage. If found, immediately report damage to the last carrier. Check the unit rating plate to confirm that delivered unit matches order.

General

The CBX25UH air handler is designed for indoor installation only. As shipped, the unit is ready for installation in either upflow, horizontal left-hand and right-hand air discharge applications. Electric heat, down flow air discharge application kits, air filters and other various accessories are available and listed in the CBX25UH Product Specification bulletin for ordering. All units come with a factory installed check/expansion valve.

Unit Dimensions

CBX25UH Unit Dimensions - inches (mm)

Front View: Shows the front of the air handler with labels for AIR FLOW, SUCTION LINE, LIQUID LINE, CONDENSATE DRAIN PIPING PLATE (2-1/4 x 3-3/4), FILTER ACCESS, and dimensions A, B, C, D, E, F, G. Also indicates LINE VOLTAGE (Right, Left and Top) and LOW VOLTAGE (Right Side Only) connection points.

Side View: Shows the side of the air handler with labels for AIR FLOW, and dimensions A, B, C, H. Also indicates LINE VOLTAGE and LOW VOLTAGE connection points.

Requirements

Excessive Weight Hazard - Use two or more people when moving and installing the unit. Failure to do so can result in back or other type of injury.

The CBX25UH units are designed to match, and must be used with, outdoor units as rated. The indoor sections are manufactured with a check/expansion valve (TXV) to provide optimum refrigerant control and system performance with a variety of different capacities of outdoor units.

Physical contact with metal edges and corners while applying excessive force or rapid motion can result in personal injury. Be aware of, and use caution when working near these areas during installation or while servicing this equipment.

These instructions are intended as a general guide and do not supersede local or national codes in any way. Consult authorities having jurisdiction before installation. Compliance with all local, state, or national codes pertaining to this type of equipment should be determined prior to installation. Read this instruction manual, as well as the instructions supplied in separate equipment, before starting the installation.

In addition to conforming to manufacturer's installation instructions and local municipal building codes, installation of Lennox air handler units (with or without optional electric heat), MUST conform with National Fire Protection Association (NFPA) standards: "Standard for Installation of Air Conditioning and Ventilation Systems" (NFPA No. 90A) and "Standard for Installation of Residence Type Warm Air Heating and Air Conditioning Systems" (NFPA No. 90B).

All models are designed for indoor installation only. The installation of the air handler, field wiring, duct system, etc. must conform to the requirements of the National Electrical Code, ANSI/NFPA No. 70 (latest edition) in the United States, and any state laws, and local ordinances (including plumbing or wastewater codes). Local authorities having jurisdiction should be consulted before installation is made. Such applicable regulations or requirements take precedence over the general instructions in this manual.

Install the conditioned air plenum, ducts and air filters (provided) in accordance with NFPA 90B Standard for the Installation of Warm Air Heating and Air-Conditioning Systems (latest edition).

The air handler is shipped from the factory completely assembled. The unit is provided with flanges for the connection of the duct system.

Do not remove the cabinet knockouts until it has been determined which knockouts will need to be removed for the installation.

Select the final air discharge position which best suits the site conditions. Consider required clearances, space, routing requirements for refrigerant line, condensate disposal, filters, duct system, wiring, and accessibility for service. Refer to the air handler rating plate on the air handler for specific information.

Danger of explosion. Keep flammable materials and vapors, such as gasoline, away from air handler. Place air handler so that heating elements are at least 18 inches (46 cm) above the floor for a garage installation. Failure to follow these instructions can result in death, explosion, or fire.

NOTES:

• During cooling operation, excessive sweating may occur if the air handler is installed in a warm and humid space.
• If installed in an unconditioned space, sealant should be applied around the electrical wires, refrigerant tubing, and condensate lines where they enter the cabinet.
• Electrical wires should be sealed on the inside where they exit the conduit opening. Sealant is required to prevent air leakage into, and condensate from forming inside of, the air handler, the control box, and on the electrical controls.
• This unit is approved for installation clearance to combustible material as stated on the unit rating plate. Accessibility and service clearances must take precedence over combustible material clearances.
• The air handler must be installed so that free access is allowed to the coil/filter compartment and blower/control compartment.

Installation Clearances

NON-DUCTED RETURN CLOSET INSTALLATION

The air handler can be installed in a closet with a false bottom to form a return air plenum. It may also be installed with a return air plenum under the air handler. Louvers or return air grilles are field-supplied. Local codes may limit application of systems without a ducted return to single story buildings.

When a CBX25UH unit is installed in a closet with a louvered return opening, the minimum open area for the louvers will be:

• 320 square inches for -018 and -024 models;
• 360 square inches for -030 and -036 models;
• 450 square inches for -042 thru -060 models.

If the free area is not known, assume a 25% free area for wood or a 75% free area for metal louvers or grilles. Using the louver dimensions and the 25% or 75% assumption, determine if the open area meets the minimum open area listed above.

Installation

If a return air plenum is used, the return air grille should be immediately in front of the opening in the plenum to allow for the free flow of return air. When not installed in front of the opening, there must be adequate clearance around the air handler to allow for the free flow of return air.

Each unit consists of a blower assembly, refrigerant coil, and controls, in an insulated galvanized steel factory finished enclosure. Knockouts are provided for electrical wiring entrance.

For ease in installation, it is best to make any necessary coil configuration changes before setting air handler in place.

REFRIGERANT METERING DEVICE

CBX25UH units are equipped with a factory-installed check expansion valve.

UPFLOW APPLICATION

1. The air handler must be supported on the bottom only and set on solid floor or field-supplied support frame. Securely attach the air handler to the floor or support frame.
2. If installing a unit in an upflow application, remove the horizontal drain pan. IMPORTANT - The horizontal drain pan is not required in upflow air discharge installations; its removal provides the best efficiency and air flow.
3. Place the unit in the desired location and slope unit as previously mentioned. Connect return and supply air plenums as required using sheet metal screws.
4. Install units that have no return air plenum on a stand that is at least 14" from the floor. This will allow proper air return.

Figure 1. Upflow Configuration: Diagram shows UPFLOW DRAIN PAN, HORIZONTAL DRAIN CONNECTIONS (NOT USED), UPFLOW DRAIN CONNECTIONS (BOTH SIDES; USE ONE SIDE OR OTHER). A note indicates "HORIZONTAL DRAIN PAN IMPORTANT! REMOVE PAN FOR BEST EFFICIENCY AND AIR FLOW."

HORIZONTAL APPLICATIONS

When removing the coil, there is possible danger of equipment damage and personal injury. Be careful when removing the coil assembly from a unit installed in right- or left-hand applications. The coil may tip into the drain pan once it is clear of the cabinet. Support the coil when removing it.

Figure 2. Suspending Horizontal Unit: Diagram shows a method for suspending the unit using angle iron or sheet metal and screws. Labels include AIR FLOW, FRONT VIEW, END VIEW, ELECTRICAL INLET CLEARANCE 4 IN. (102 MM).

NOTE: When the unit is installed in horizontal applications, a secondary drain pan is recommended. Refer to local codes.

NOTE: This unit may be installed in left-hand or right-hand air discharge horizontal applications. Adequate support must be provided to ensure cabinet integrity. Ensure that there is adequate room to remove service and access panels if installing in the horizontal position.

LEFT-HAND DISCHARGE

1. Determine knockouts required for drain line connections.
2. With access door removed, knock out drain line opening for installing drain lines.
3. Set unit so that it is sloped toward the drain pan end of the unit (see figure 10).
4. The horizontal configuration is shown in figure 3.

Figure 3. Left-Hand Discharge Configuration: Diagram shows AIR FLOW, KNOCKOUT, and LEFT-HAND DRAINS. Labels indicate "Drains".

Installation (Continued)

If the unit is suspended, the entire length of the cabinet must be supported. If you use a chain or strap, use a piece of angle iron or sheet metal attached to the unit (either above or below) to support the length of the cabinet. Use securing screws no longer than 1/2 inch to avoid damaging the coil or filter. See figure 2. Use sheet metal screws to connect the return and supply air plenums as required.

RIGHT-HAND AIR DISCHARGE

For horizontal right-hand air discharge, the following field modifications are required:

1. Remove and set aside blower and coil access covers.
2. Remove bracket(s) securing pan(s) to unit as illustrated in figures 4 and 5.
3. Remove coil assembly, bottom drain pan and horizontal drain pan as one assembly from the air handler.
4. Move the horizontal drain pan to the opposite side of the coil. Be sure drain holes toward the back of the unit are plugged. Remove the plugs from the front drain pan ports.
5. Re-install modified coil/drain pan assembly in air handler in the same orientation as before (figures 6 and 7).

Figure 4. Remove Main Drain Pan Mounting Bracket (-018 through -036): Diagram shows removing a bracket securing the main drain pan to the unit.

Figure 5. Remove Horizontal and Main Drain Pan Mounting Brackets (-042 through -060): Diagram shows removing brackets securing both drain pans to the unit.

Figure 6. Install Main Drain Pan Mounting Bracket (-018 through -036): Diagram shows installing a bracket securing the main drain pan to the unit.

Figure 7. Install both Horizontal and Main Drain Pan Brackets (-042 through -060): Diagram shows installing both horizontal and main drain pan brackets.

6. Remove two screws securing the blow-off prevention bracket. Rotate the brackets 180° and reinstall using the same screws. See figure 8.

Figure 8. Blow-Off Prevention Plate: Diagram shows the blow-off prevention bracket in the horizontal left (factory default) position and the horizontal right position. Instructions are given to remove screws, rotate the bracket, and reinstall.

Condensate Drain

❗ IMPORTANT: On units of this type, where the blower "draws" rather than "blows" air through the coil, traps must be installed in the condensate drain lines (primary and auxiliary, if used). Traps prevent the blower from drawing air through the drain lines into the air supply.

Figure 9. Typical Main and Overflow Drain: Diagram illustrates condensate drain setup. It shows an overflow drain line, main drain, vent, Lennox P-trap, secondary drain pan, and notes on trap depth and drain line slope. Key elements include: "ABOVE FINISHED SPACE?", "OVERFLOW DRAIN LINE", "VENT MUST EXTEND ABOVE HEIGHT OF COIL DRAIN PAN BY TWO INCHES (51MM)", "CLEAN OUT", "AIR HANDLER DRAIN PAN", "MAIN DRAIN", "OVERFLOW DRAIN", "SECONDARY DRAIN PAN", "LENNOX P-TRAP 49P66, J-TRAP # 91P90 OR ANY PVC SCH 40 P- OR J-TRAP 3/4"", "TRAP DEPTH", "TO APPROVED DRAIN", "DRAIN LINE SHOULD SLOPE A MINIMUM OF ONE INCH PER 10 FEET (25MM PER 3 METERS)". Notes specify secondary drain pan requirements and trap depth.

❗ A field-fabricated secondary drain pan, with a drain pipe to the outside of the building, is required in all installations over a finished living space or in any area that may be damaged by overflow from the main drain pan. In some localities, local codes may require a secondary drain pan for any horizontal installation.

The air handler is provided with 3/4" NPT condensate drain connections.

SLOPING THE DRAIN

Make sure the unit is sloped (similar to the slope shown in figure 10) (horizontal or upflow) so that the drain pan will empty completely without water standing in the pan.

Figure 10. Sloping the Drain: Diagram shows a level plane and a drain corner, indicating that the corner opposite the drain should be 5/8" (+/- 1/8") higher than the drain corner.

INSTALL CONDENSATE DRAIN

1. Remove the appropriate drain knockouts. If necessary, remove the indoor coil assembly from the cabinet.
2. Connect primary drain line connection to the primary drain pan connection. The primary drain connection is flush with the bottom of the inside of the pan. Secondary connection is raised above the bottom of the inside of the pan.

NOTE: When making drain fitting connections to the drain pan, hand tighten the fitting and use a thread sealant. Over-tightening the fittings can split connections on the drain pan.

3. If the auxiliary drain line is to be used, remove the plug and route the drain line so that water draining from the outlet will be easily noticed by the homeowner. The auxiliary drain line does not require venting or a trap. Refer to local codes.
4. After removal of drain pan plugs, check the drain port to see if holes have been drilled. If not drilled, use a 19/32" bit to drill out the primary drain hole; use a 3/8" drill bit for the secondary drain hole. Remove all drill shavings.
5. Make sure drain ports and drain pan are free of all debris.
6. Plug and check any unused drain pan openings for tightness. Torque plugs to 30 in. lb. to prevent water leaks or seepage from the drain pan.
7. Install a 2" trap in the primary drain lines as close to the unit as practical (see figure 9). Make sure the top of the trap is below the connection to the drain pan to allow complete drainage of the pan.

NOTE: Horizontal runs must have an anti-siphon air vent (standpipe) installed ahead of the horizontal run (See figure 9). An extremely long horizontal run may require an oversized drain line to eliminate air trapping.

NOTE: Do not operate air handler without a drain trap. The condensate drain is on the negative pressure side of the blower; therefore, air being pulled through the condensate line will prevent positive drainage without a proper trap.

8. Route the drain line to the outside or to an appropriate drain. Drain lines must be installed so they do not block service access to the front of the air handler. A 24" clearance is required for filter, coil, or blower removal and service access.

NOTE: Check local codes before connecting the drain line to an existing drainage system. Insulate the drain lines where sweating could cause water damage.

TEST CONDENSATE DRAIN

Test the drain pan and drain line after installation:

1. Pour several quarts of water into drain pan, enough to fill drain trap and line.
2. Check to make sure the drain pan is draining completely, no leaks are found in drain line fittings, and water is draining from the end of the primary drain line.
3. Correct any leaks found.

Duct System and Filters

DUCT SYSTEM

The air handler is provided with flanges for the connection of the plenum and ducts. The air handler is equipped with flanges that can form a filter rack for the installation of the air filter, or the filter may be installed as part of the return air duct system.

Supply and return duct system must be adequately sized to meet the system's air requirements and static pressure capabilities. The duct system should be insulated with a minimum of 1" thick insulation with a vapor barrier in conditioned areas or 2" minimum in unconditioned areas.

Duct System and Filters (Continued)

If a high-efficiency filter is being installed as part of this system to ensure better indoor air quality, the filter must be properly sized. High-efficiency filters have a higher static pressure drop than standard-efficiency glass/foam filters. If the pressure drop is too great, system capacity and performance may be reduced. The pressure drop may also cause the limit to trip more frequently during the winter and the indoor coil to freeze in the summer, resulting in an increase in the number of service calls.

Before using any filter with this system, check the specifications provided by the filter manufacturer against the data given in the appropriate Lennox Product Specifications bulletin. Additional information is provided in Service and Application Note ACC-00-2 (August 2000).

Supply plenum should be the same size as the flanged opening provided around the blower outlet and should extend at least 3 ft. from the air handler before turning or branching off plenum into duct runs. The plenum forms an extension of the blower housing and minimizes air expansion losses from the blower.

INSTALLING DUCT SYSTEM

Connect supply air duct to the flange on top of the air handler. If an isolation connector is used, it must be nonflammable.

A return air duct system is recommended. If the unit is installed in a confined space or closet, a return connection must be run, full size, to a location outside the closet.

Connecting Refrigerant Lines

Refrigerant lines must be connected by a qualified technician in accordance with established procedures.

Refrigerant lines must be clean, dehydrated, refrigerant-grade copper lines. Air handler coils should be installed only with specified line sizes for approved system combinations.

Handle the refrigerant lines gently during the installation process. Sharp bends or possible kinking in the lines will cause a restriction.

Do not remove the caps from the lines or system connection points until connections are ready to be completed.

1. Route the suction and liquid lines from the fittings on the indoor coil to the fittings on the outdoor unit. Run the lines in as direct a path as possible avoiding unnecessary turns and bends.
2. Make sure that the suction line is insulated over the entire exposed length and that neither suction nor liquid lines are in direct contact with floors, walls, duct system, floor joists, or other piping.
3. Connect the suction and liquid lines to the evaporator coil.
4. To avoid damaging the rubber grommets in the cabinet while brazing, slide the rubber grommets over the refrigerant lines until they are away from the heat source.
5. Braze using an alloy of silver or copper and phosphorus with a melting point above 1,100°F (593°C).

NOTE: Do not use soft solder.

6. Reinstall the rubber grommets after brazing is finished.
7. Make sure outdoor unit has been put in place according to the Installation Instructions and is connected to the refrigerant lines.

Sealing the Unit

Seal the unit so that warm air is not allowed into the cabinet. Warm air introduces moisture, which results in water blow-off problems. This is especially important when the unit is installed in an unconditioned area.

If installed in an unconditioned space, sealant should be applied around the electrical wires, refrigerant tubing, and condensate lines where they enter the cabinet.

There must be an airtight seal between the bottom of the air handler and the return air plenum. Use fiberglass sealing strips, caulking, or equivalent sealing method between the plenum and the air handler cabinet to ensure a tight seal. Return air must not be drawn from a room where this air handler or any gas-fueled appliance (i.e., water heater), or carbon monoxide-producing device (i.e., wood fireplace) is installed.

When sealing the cabinet, be sure to seal closed any space around the holes where the drain lines exit the cabinet using duct tape and/or Permagum. Warm air must not be allowed to enter through any gaps or holes in the cabinet.

Make sure the liquid line and suction line entry points are sealed with either ARMAFLEX material or with Permagum. Permagum may also be used to seal around the main and auxiliary drains and around open areas of electrical inlets.

Electrical Connections

Electric shock hazard! - Disconnect all power supplies before servicing. Replace all parts and panels before operating. Failure to do so can result in death or electrical shock.

Electric Shock Hazard. Can cause injury or death. Foil-faced insulation has conductive characteristics similar to metal. Be sure there are no electrical connections within a 1½" of the insulation. If the foil-faced insulation comes in contact with electrical voltage, the foil could provide a path for current to pass through to the outer metal cabinet. While the current produced may not be enough to trip existing electrical safety devices (e.g. fuses or circuit breakers), the current can be enough to cause an electric shock hazard that could cause personal injury or death.

• All field wiring must be done in accordance with National Electrical Code, applicable requirements of UL and local codes, where applicable.
• Electrical wiring, disconnect means and over-current protection are to be supplied by the installer. Refer to the air handler rating plate for maximum over-current protection, minimum circuit ampacity, as well as operating voltage.
• The power supply must be sized and protected according to the specifications supplied on the product.
• This air handler is factory-configured for 240 volt, single phase, 60 cycles. For 208-volt applications, see "208 Volt Conversion" later in this section.
• For optional field-installed electric heat applications, refer to the instructions provided with the accessory for proper installation.

USE COPPER CONDUCTORS ONLY

1. Disconnect all power supplies.
2. Remove the air handler access panel.
3. Route the field supply wires to the air handler electrical connection box.
4. Use UL-listed wire nuts to connect the field supply conductors to the unit black and yellow leads, and the ground wire to ground terminal marked GND.
5. Replace the air handler access panel.

Figure 11. Making Electrical Connections: Diagram shows electrical connections. Labels include "CONNECT BLACK AND YELLOW WIRES TO FIELD-PROVIDED CONDUCTORS." and "CONNECT GROUND WIRE TO GROUND TERMINAL MARKED "GND"".

208 VOLT CONVERSION

1. Disconnect all power supplies.
2. Remove the air handler access panel.
3. Using the wiring diagram located on the unit access panel as a reference, move the 2 connected black transformer leads from the 240 volt terminal on the transformer to the 208 volt terminal on the transformer.

Electrically ground air handler. Connect ground wire to ground terminal marked "GND". Failure to do so can result in death or electrical shock.

Airflow - Cooling Blower Speed

The cooling blower speed is factory configured to provide correct airflow for an outdoor unit that matches the cooling capacity rating of the air handler.

If the outdoor unit is smaller than the maximum cooling capacity rating for the air handler, the cooling blower speed may need to be changed. Refer to blower performance chart, table 2 on page 11.

Electric shock hazard! - Disconnect all power supplies before servicing. Replace all parts and panels before operating. Failure to do so can result in death or electrical shock.

CHANGE BLOWER SPEED

1. Disconnect all power supplies.
2. Remove the air handler access panel.
3. Locate pin number 2 on the blower relay. Two black wires are connected to this terminal pin. One connects to pin number 5 on the blower relay, one connects to an in-line splice connecting to a red wire.
4. Remove the wire going to the 4-pin blower motor connector from the splice.
5. Connect the blower lead [Red (LO), Black (HI)] onto the splice from the 4-pin blower motor connector.

NOTE: Reuse the factory-installed plastic cap on whichever wire is not used.

6. Replace all panels.
7. Reconnect power.

Figure 12. Low Voltage Connections (3-Speed PSC Motor) - Field Wiring: Diagrams show wiring configurations for THERMOSTAT to AIR HANDLER for COOLING-ONLY APPLICATION, COOLING APPLICATION WITH ELECTRIC HEAT, HEAT-ONLY APPLICATION, HEAT PUMP APPLICATION WITH ELECTRIC HEAT. Notes indicate connecting common wire if required.

Blower Performance

Figure 13. Changing Blower Speed: Diagram illustrates the blower relay harness and 4-pin blower connector, showing wire connections for changing speed.

NOTE: Refer to wiring diagram located on the unit access panel (or figure 13 above) and blower performance (table 2).

• All air data measured external to unit with 1 inch non-pleated air filter in place.
• All factory settings are medium speed except the -48 which is set to low speed from the factory.
• All data given while air handler is operating with a dry DX coil.

• Blower Performance (CFM vs. ESP inches H2O)
• Cooling speeds should not be reduced below factory setting.
• Units with electric heat approved at 0.5" maximum and medium blower speed minimum.

Check-out Procedures

NOTE - Refer to outdoor unit installation instructions for system start-up instructions and refrigerant charging instructions.

PRE-START-UP CHECKS

• Is the air handler properly and securely installed?
• If horizontally configured, is the unit sloped up to 5/8 inch toward drain lines?
• Will the unit be accessible for servicing?
• Has an auxiliary pan been provided under the unit with separate drain for units installed above a finished ceiling or in any installation where condensate overflow could cause damage?
• Have ALL unused drain pan ports been properly plugged?
• Has the condensate line been properly sized, run, trapped, pitched, and tested?
• Is the duct system correctly sized, run, sealed, and insulated?
• Have all cabinet openings and wiring been sealed?
• Is the indoor coil factory-installed TXV properly sized for the outdoor unit being used?
• Have all unused parts and packaging been disposed of?
• Is the filter clean, in place, and of adequate size?
• Is the wiring neat, correct, and in accordance with the wiring diagram?
• Is the unit properly grounded and protected (fused)?
• Is the thermostat correctly wired and in a good location?
• Are all access panels in place and secure?

CHECK BLOWER OPERATION

• Set thermostat to FAN ON.
• The indoor blower should come on.

CHECK COOLING OPERATION

• Set thermostat to force a call for cooling (approximately 5°F lower than the indoor ambient temperature).
• The outdoor and indoor units should come on immediately.
• Check the airflow from a register to confirm that the system is moving cooled air.
• Set the thermostat 5°F higher than the indoor temperature. The indoor blower and outdoor unit should cycle off. Air handler should cycle off 45 seconds after the outdoor unit shuts off.

CHECK ELECTRIC HEATER (IF USED)

• Set thermostat to call for auxiliary heat (approximately 5°F above ambient temperature). The indoor blower and auxiliary heat should come on together. Allow a minimum of 3 minutes for all sequencers to cycle on.
• Set the thermostat so that it does not call for heat. Allow up to 5 minutes for all sequencers to cycle off.

Operation

TIME DELAY RELAY

Blower time delay operation:

1. When cooling demand is initiated, there is a 1 second motor-on delay.
2. After the motor-on delay expires, motor ramps up to 100% and runs at 100% until cooling demand is satisfied.
3. Once demand is met, motor runs at 100% for 45 seconds.
4. Motor ramps down to stop.

Figure 14. Blower Time Delay: Diagram shows a timeline for blower delay operation: 1 SECOND DELAY, COOLING DEMAND, 100% CFM, 45 SECS, OFF.

COOLING (COOLING ONLY OR HEAT PUMP)

When the thermostat calls for cooling, 24 volts is put on the blower time-delay relay coil and then the indoor blower relay energizes. The normally open contacts close, causing the indoor blower motor to operate. The circuit between R and Y is completed, closing the circuit to the contactor in the outdoor unit, starting the compressor and outdoor fan motor.

On heat pumps, circuit R and O energizes the reversing valve, switching the valve to the cooling position. (The reversing valve remains energized as long as the thermostat selector switch is in the COOL position.)

At the completion of the cooling demand the indoor blower and outdoor unit should cycle off. Air handler should cycle off 45 seconds after the outdoor unit shuts off.

HEATING (ELECTRIC HEAT ONLY)

When the thermostat calls for heat, the circuit between R and W is completed, and the heat sequencer is energized. A time delay follows before the heating elements and the indoor blower motor come on. Units with a second heat sequencer can be connected with the first sequencer to W on the thermostat subbase, or they may also be connected to a second stage on the subbase.

HEATING (HEAT PUMP)

When the thermostat calls for heating, 24 volts is put on the blower time-delay relay coil. Then normally open contacts close, causing the indoor blower motor to operate. The circuit between R and Y is completed, closing the circuit to the contactor in the outdoor unit, starting the compressor and outdoor fan motor.

If the room temperature should continue to fall, the circuit between R and W1 is completed by the second-stage heat room thermostat. Circuit R-W1 energizes a heat sequencer. The completed circuit will energize supplemental electric heat (if applicable). Units with a second heat sequencer can be connected with the first sequencer to W1 on the thermostat. They may also be connected to a second heating stage W2 on the thermostat subbase.

EMERGENCY HEAT (HEATING HEAT PUMP)

If the selector switch on the thermostat is set to the emergency heat position, the heat pump will be locked out of the heating circuit, and all heating will be electric heat (if applicable). A jumper should be placed between W2 and E on the thermostat subbase so that the electric heat control will transfer to the first-stage heat on the thermostat. This will allow the indoor blower to cycle on and off with the electric heat when the fan switch is in the AUTO position.

Maintenance

Do not operate system without a filter. A filter is required to protect the coil, blower, and internal parts from excessive dirt and dust. The filter is placed in the return duct by the installer.

• Inspect air filters at least once a month and replace or clean as required. Dirty filters are the most common cause of inadequate heating or cooling performance.
• Replace disposable filters. Cleanable filters can be cleaned by soaking in mild detergent and rinsing with cold water.
• Install new/clean filters with the arrows on the side pointing in the direction of airflow. Do not replace a cleanable (high velocity) filter with a disposable (low velocity) filter unless return air system is properly sized for it.
• If water should start coming from the secondary drain line, a problem exists which should be investigated and corrected. Contact a qualified service technician.

Cabinet Insulation

DAMAGED INSULATION MUST BE REPAIRED OR REPLACED before the unit is put back into operation. Insulation loses its insulating value when wet, damaged, separated or torn.

Matt- or foil-faced insulation is installed in indoor equipment to provide a barrier between outside air conditions (surrounding ambient temperature and humidity) and the varying conditions inside the unit. If the insulation barrier is damaged (wet, ripped, torn or separated from the cabinet walls), the surrounding ambient air will affect the inside surface temperature of the cabinet. The temperature/humidity difference between the inside and outside of the cabinet can cause condensation on the inside or outside of the cabinet which leads to sheet metal corrosion and subsequently, component failure.

REPAIRING DAMAGED INSULATION

Areas of condensation on the cabinet surface are an indication that the insulation is in need of repair.

If the insulation in need of repair is otherwise in good condition, the insulation should be cut in an X pattern, peeled open, glued with an appropriate all-purpose glue and placed back against the cabinet surface, being careful to not overly compress the insulation so the insulation can retain its original thickness. If such repair is not possible, replace the insulation. If using foil-faced insulation, any cut, tear, or separations in the insulation surface must be taped with a similar foil-faced tape.

Figure 15. Repairing Insulation: Diagram shows steps for repairing insulation: 1. CUT INSULATION IN X PATTERN, 2. APPLY GLUE, 3. PRESS GLUED TABS AGAINST CABINET. A note emphasizes "GLUE - make sure there is full coverage of glue on the metal or insulation so there are no areas where air pockets may form which can lead to sweating."

Start-Up and Performance Checklist

Installing Contractor's Name: _______________________ Installing Contractor's Phone:_______________________ Job Address:____________________________________ Installing Date:_______________________________ Air Handler Model #:___________________________

Figure 16. Start-Up and Performance Checklist (Upflow Configuration): Diagram shows a checklist with numbered components and fields for recording measurements and checks. Components include: 1. DUCT SYSTEM, 2. INTEGRATED CONTROL, 3. VOLTAGE CHECK, 4. DRAIN LINE, 5. TOTAL EXTERNAL STATIC (dry coil), 6. ELECTRIC HEAT AMPS, 7. INDOOR BLOWER AMPS, INDOOR BLOWER CFM, 8. TEMPERATURE DROP (Cooling Mode), 8. TEMPERATURE RISE (Heating Mode), 9. THERMOSTAT.

1 DUCT SYSTEM

• SUPPLY AIR DUCT: Sealed [ ] Insulated (if necessary) [ ] Registers Open and Unobstructed [ ]
• RETURN AIR DUCT: Sealed [ ] Filter Installed and Clean [ ] Registers Open and Unobstructed [ ]

2 INTEGRATED CONTROL

• Jumpers Configured Correctly (if applicable) [ ]
• Appropriate Links in Place (if applicable) [ ]

3 VOLTAGE CHECK

• Supply Voltage: ___________ Low Voltage: ___________
• Electrical Connections Tight [ ]

4 DRAIN LINE

• Leak Free [ ]

5 TOTAL EXTERNAL STATIC (dry coil) dry coil wet coil

• Supply External Static: ______ ______
• Return External Static: ______ ______
• Total External Static = ______ ______

6 ELECTRIC HEAT AMPS ____________

7 INDOOR BLOWER AMPS___________ INDOOR BLOWER CFM____________

8 TEMPERATURE DROP (Cooling Mode)

• Return Duct Temperature: ___________
• Supply Duct Temperature: ___________
• Temperature Drop = ___________

8 TEMPERATURE RISE (Heating Mode)

• Return Duct Temperature: __________
• Supply Duct Temperature: __________
• Temperature Rise = __________

9 THERMOSTAT

• Adjusted and Programmed [ ]
• Operation Explained to Owner [ ]

Explained Operation of System to Homeowner [ ]

Technician's Name:_______________________ Date Start-Up & Performance Check Completed:__________

Figure 17. Start-Up and Performance Checklist (Horizontal Configuration): Diagram shows a checklist similar to Figure 16, adapted for horizontal configuration.