Lennox Merit Series Air Handler Installation Instructions

CBA25UH Series - Installation Instructions

General Information

The CBA25UH series air handler with an all-aluminum coil is designed for indoor installation. It is shipped ready for upflow, horizontal left-hand, or right-hand air discharge applications. Electric heat, downflow kits, and air filters are available separately. These instructions are a general guide and do not supersede local or national codes. Always consult authorities having jurisdiction.

CAUTION: Handling the unit may involve contact with sharp sheet metal edges. Wear gloves and protective clothing.

WARNING: Excessive weight hazard. Use two or more people for moving and installing the unit to prevent injury.

IMPORTANT: CBA25UH units feature a factory-installed check/expansion valve for optimal refrigerant control. They must be installed as part of a matched system as outlined in the product specification bulletin. Compliance with local, state, and national codes, including NFPA standards (90A, 90B) and the National Electrical Code (ANSI/NFPA No. 70), is mandatory.

WARNING: Keep flammable materials and vapors away from the air handler. For garage installations, ensure heating elements are at least 18 inches (46 cm) above the floor to prevent explosion or fire.

IMPORTANT: In unconditioned spaces, apply sealant around electrical wires, refrigerant piping, and condensate lines where they enter the cabinet to prevent condensation and moisture buildup.

IMPORTANT: Ensure adequate clearance for service access to the coil/filter and blower/control compartments.

Unit Dimensions and Clearances

CBA25UH Unit Dimensions – Upflow – Inches (mm)

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 or with a return air plenum underneath. Louvers or return air grilles are field-supplied. Local codes may limit systems without a ducted return to single-story buildings.

Minimum open area for louvers:

• 320 sq. in. for -018 and -024 models
• 360 sq. in. for -030 and -036 models
• 450 sq. in. for -042 thru -060 models

If the free area is unknown, assume 25% for wood or 75% for metal louvers. Ensure the open area meets the minimum requirements.

If a return air plenum is used, the return air grille should be in front of the opening for free airflow. Adequate clearance must be maintained around the unit for airflow.

Installation

Each unit comprises a blower assembly, refrigerant coil, and controls in a galvanized steel enclosure. Knockouts are provided for electrical wiring. Make any necessary coil configuration changes before setting the air handler in place.

Upflow Application

1. Support the unit on the bottom only, on a solid floor or field-supplied support frame. Securely attach the unit.
2. For upflow discharge, remove the horizontal drain pan. This improves efficiency and airflow.
3. Place the unit in the desired location and slope it. Connect return and supply air plenums using sheet metal screws.
4. If there is no return air plenum, install the unit on a stand at least 14 inches from the floor to allow proper air return.

Diagram: Figure 1. Upflow Configuration

This diagram illustrates the upflow configuration of the air handler. It shows the unit placed on a floor or support frame, with the supply and return air plenums connected. The horizontal drain pan is shown as removed for upflow applications. Airflow is indicated from bottom to top.

Horizontal Applications

IMPORTANT: Be careful when removing the coil assembly to avoid equipment damage and personal injury. Support the coil when removing it.

NOTE: For horizontal installations, a secondary drain pan is recommended. Refer to local codes. Ensure adequate support for the cabinet and access for service panels.

Right-Hand Discharge

1. Determine required drain line plugs.
2. Remove drain line plugs with access door open to install drain lines.
3. Slope the unit toward the upflow drain pan end and ensure it is level from front to back.
4. The horizontal configuration is shown in Figure 2.

Diagram: Figure 2. Right-Hand Discharge Configuration

This diagram shows the right-hand discharge configuration. It illustrates the unit with airflow exiting to the right, and drain connections on the right side.

If suspending the unit, support the entire cabinet length using angle iron or sheet metal. Use securing screws no longer than 1/2 inch.

Left-Hand Air Discharge

Field modifications are required for left-hand air discharge:

1. Remove access panels and the horizontal drip shield and corrugated padding. Discard padding.
2. Pull the coil assembly and horizontal drain pan from the unit.
3. Move drain plugs from back drain holes to front holes on the horizontal drain pan.

Diagram: Figure 4. Field Modification for Left-Hand Discharge

This diagram illustrates field modifications for left-hand discharge. It shows the rotation of the top cap and drip shield, and the relocation of drain plugs and screws to accommodate the left-hand airflow.

Continue modifications as shown in Figure 4 and Figure 5.

Diagram: Figure 5. Left-Hand Discharge Configuration

This diagram shows the left-hand discharge configuration. It illustrates the unit with airflow exiting to the left, and the horizontal drain pan positioned accordingly.

Downflow Application

Order kit number 83M57 separately for downflow applications. Follow kit instructions. Use metal or Class I supply and return air plenums. Refer to the downflow kit installation instructions.

IMPORTANT: If electric heat sections with circuit breakers (ECB29/ECB31) are installed in a downflow application, rotate the circuit breakers 180° to the UP position.

Condensate Drain

IMPORTANT: Traps must be installed in condensate drain lines (primary and auxiliary) to prevent blower from drawing air into the air supply.

Diagram: Figure 6. Typical Main and Overflow Drain

This diagram illustrates typical main and overflow condensate drain configurations. It shows the placement of traps, vents, and secondary drain pans, with notes on required trap depth and routing for different installation scenarios.

Diagram: Figure 7. Sloping the Unit for Proper Drainage

This diagram illustrates the correct sloping of the unit for proper drainage. It indicates that one corner should be higher than the drain corner, with a recommended slope.

Install Condensate Drain

The air handler has 3/4" NPT condensate drain connections. Ensure primary and secondary drain holes are clear.

Diagram: Figure 8. Drain Line Connections

This diagram shows drain line connections for all CBA25UH models. It highlights the green main drain plug and the red secondary drain plug on the drain pan, and indicates where to connect fittings and drain lines.

1. Unscrew green (main) and red (secondary) drain plugs.
2. Connect properly sized fittings and route the primary drain line to the main drain pan connection. Hand-tighten fittings and use thread sealant.
3. If using the secondary drain line, remove the plug or knockout and route the line so water drainage is noticeable. Refer to local codes for trap requirements.
4. Ensure drain ports and pan are free of debris.
5. Plug and check unused drain pan openings. Torque plugs to 30 in.-lb.
6. Install a 2" trap in the main drain line as close to the unit as practical. Ensure the top of the trap is below the drain pan connection.

NOTE: Horizontal runs require an anti-siphon air vent (standpipe). Do not operate the air handler without a trap in the main drain line, as it is on the negative pressure side of the blower.

Route drain lines to avoid blocking service access. Maintain 24" clearance for filter, coil, or blower removal.

Test Condensate Drain

1. Pour several quarts of water into the drain pan to fill the trap and line.
2. Check that the drain pan drains completely and fittings are not leaking. Water should drain from the primary drain line.
3. Correct any leaks.

Duct System and Filters

The air handler includes flanges for supply plenum connection. Duct systems should be adequately sized and insulated (minimum 1" in conditioned areas, 2" in unconditioned areas). Supply plenum should extend at least 3 ft. from the unit.

Filters

Table 1. Unit Air Filter Size Chart

IMPORTANT: High efficiency filters may reduce system capacity if pressure drop is too great. Check filter specifications against Lennox data.

Brazing Refrigerant Lines

Refrigerant lines must be connected by a qualified technician. Use clean, dry, refrigerant-grade copper lines. Handle lines gently to avoid bends or kinks.

WARNING: POE oils absorb moisture quickly. Keep the system closed and do not remove line set caps until ready to make connections.

WARNING: Bleeding refrigerant charge can pressurize the low side, potentially igniting refrigerant and oil mixture if a brazing torch is applied. Check pressures before heating.

WARNING: Use nitrogen for pressurizing at 1-2 psig. Perform in well-ventilated areas. Wear protective gear.

CAUTION: Brazing alloys and flux are hazardous. Avoid breathing fumes and wear protective gear.

IMPORTANT: Purge with low-pressure nitrogen during brazing to prevent oxidation and moisture.

Refrigerant Lines

Route suction and liquid lines directly, avoiding turns and bends. Insulate the suction line entirely. Ensure lines do not contact floors, walls, or other piping.

Slide rubber grommets over lines during brazing to protect them from heat.

Diagram: Figure 10. Brazing Connections

This diagram illustrates the steps for brazing refrigerant line connections. It shows the process of removing access panels, connecting gauges, using nitrogen flow, applying wet rags for cooling, and brazing the connections.

Sealing the Unit

Seal the unit to prevent warm, moist air from entering the cabinet, which can cause condensation and corrosion. Use fiberglass sealing strips or equivalent to ensure an airtight seal between the air handler and the return air plenum. Seal around drain line holes with duct tape or Permagum.

Electrical Connections

WARNING: Disconnect all power supplies before servicing. Failure to do so can result in death or electrical shock.

Run 24V Class II wiring through specified low-voltage openings and line voltage wiring through specified high-voltage openings. Do not combine voltages in one opening.

WARNING: Unit must be properly grounded. Line voltage is present at all components when the unit is not in operation. Disconnect all remote power supplies before opening access panels.

Wiring must conform to the National Electrical Code (ANSI/NFPA No. 70) and local codes. Refer to wiring diagrams. Check the unit nameplate for minimum circuit ampacity and maximum over-current protection.

Installer supplies wiring, disconnect means, and over-current protection. Select conductors per NEC tables. The unit is factory-configured for 240 volt, single phase, 60 cycles. Refer to 208-volt conversion instructions if needed.

Separate openings are provided for 24V low voltage and line voltage. Use provided caps to seal unused conduit holes.

Diagram: Figure 11. Electrical Connections (Upflow Configuration)

This diagram shows typical electrical connections for the air handler in an upflow configuration, illustrating wiring to the control box and components.

Diagram: Figure 12. Control Panel Relocated to End Panel (Left-Hand Horizontal Configuration)

This diagram shows the control panel relocated to the end panel for specific right-hand discharge configurations to avoid moisture damage.

Diagram: Figure 13. Converting Unit from 240VAC to 208VAC

This diagram illustrates the process of converting the unit's voltage from 240VAC to 208VAC by adjusting transformer connections.

Typical Wiring Diagram

Diagram: Figure 14. Typical Wiring Diagram – CBA25UH Air Handler with Electric Heat

This is a wiring diagram for the CBA25UH air handler with electric heat. It details connections for circuit breakers, sequencers, heaters, blower motor, transformer, and thermostat, including component labels and wire colors.

Air Flow – Cooling Blower Speed

The cooling blower speed is factory set for the outdoor unit's cooling capacity. If the outdoor unit is smaller, the cooling blower speed may need adjustment. Refer to blower performance charts.

WARNING: Disconnect all power supplies before servicing.

Change Blower Speed

1. Disconnect all power supplies.
2. Remove access panel.
3. Locate pin 2 on the blower relay.
4. Select the required blower motor speed (Low-Red, Med-Blue, High-Black) and connect to the 4-pin blower relay harness connector.
5. Replace panels and reconnect power.

Diagram: Figure 16. Changing Blower Speed

This diagram shows the blower relay and the 4-pin blower connector used for changing blower speed. It indicates wire colors for different speeds (Low, Medium, High).

Blower Performance

Table 2. CBA25UH Blower Performance (3-Speed PSC) – 240V (CFM @ ESP. – in. W. C.)

Notes:

• Blower Performance (CFM vs. ESP) values are shown.
• Cooling speeds should not be reduced below factory settings.
• Units with electric heat are approved at 0.5" maximum and medium blower speed minimum.
• Downflow applications run on high speed with electric heat.

Check-out Procedures

PRE-START-UP CHECKS:

• Is the air handler properly installed?
• If horizontal, is it sloped towards the drain lines?
• Is the unit accessible for servicing?
• Has an auxiliary pan been provided if installed above a finished ceiling or in an area where condensate overflow could occur?
• Are all drain pan ports 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 TXV properly sized?
• Have all unused parts and packaging been disposed of?
• Is the filter clean, in place, and of adequate size?

Operation

Time Delay Relay

The blower has a time delay operation:

1. 1-second motor-on delay when cooling demand is initiated.
2. Motor ramps to 100% after delay and runs until cooling demand is satisfied.
3. Motor runs at 100% for 45 seconds after cooling demand is met.
4. Motor ramps down to stop.

Diagram: Figure 17. Blower Time Delay

This diagram illustrates the blower time delay operation sequence, showing a 1-second delay on cooling demand, 100% ramp-up, 45-second run-on after demand is met, and ramp-down to stop.

Cooling (Cooling Only or Heat Pump)

When the thermostat calls for cooling, the blower operates. The circuit to the outdoor unit's contactor is completed, starting the compressor and outdoor fan. For heat pumps, the reversing valve is energized for cooling.

Heating (Electric Heat Only)

When the thermostat calls for heat, the heat sequencer is energized, followed by heating elements and the indoor blower.

Heating (Heat Pump)

When the thermostat calls for heating, the blower operates. The circuit to the outdoor unit's contactor is completed, starting the compressor and outdoor fan motor. If room temperature drops, a second-stage heat is activated.

Emergency Heat (Heating Heat Pump)

If the thermostat is set to emergency heat, the heat pump is locked out, and only electric heat operates. A jumper may be needed to transfer electric heat control to the first-stage heat.

Homeowner Maintenance

IMPORTANT: Do not operate without a filter. Filters protect the coil and blower. Inspect filters monthly and clean or replace as needed. Dirty filters reduce performance.

Repairing or Replacing Cabinet Insulation

IMPORTANT: Damaged insulation must be repaired or replaced before operation. Insulation loses value when wet or damaged.

The insulation provides a barrier between indoor and outdoor conditions. If damaged, it can cause condensation and corrosion.

Diagram: Figure 18. Repairing Insulation

This diagram illustrates the process of repairing damaged cabinet insulation, showing steps to cut, glue, and press insulation back into place.

Professional Maintenance

NOTICE: Failure to follow instructions can damage the unit. Aluminum coils may be damaged by solutions with pH below 5 or above 9. Clean with potable water at moderate pressure (under 50 psi). If necessary, use a coil cleaner with a pH of 5-9. Rinse thoroughly. In coastal areas, clean with potable water several times a year to prevent corrosion.

Use of Air Handler During Construction

Lennox does not recommend using the air handler during construction due to potential damage from low temperatures, harmful vapors, and clogged filters. If used, follow these conditions:

• A room thermostat must control the unit; fixed jumpers are not allowed.
• Air filter must be installed and maintained. Replace filter after construction.
• Evaporator coil, supply fan, and duct system must be cleaned after construction.
• Verify all operating conditions per installation instructions.

13ACX Series - Installation Instructions

General Information

This 13ACX outdoor unit is for use with HFC-410A refrigerant and requires an approved indoor unit. Consult the Lennox 13ACX Product Specifications bulletin (EHB) for approved match-ups. These instructions are a general guide and do not supersede local codes.

WARNING: California has determined this product may contain chemicals causing illness, death, cancer, birth defects, or reproductive harm.

WARNING: Improper installation, adjustment, alteration, service, or maintenance can cause personal injury, loss of life, or property damage. Installation and service must be performed by a licensed professional.

CAUTION: Turn electrical power OFF at the disconnect switch before servicing.

CAUTION: Handle equipment carefully to avoid personal injury from sharp sheet metal edges.

Clearances

Diagram: Figure 1. Clearances

This diagram shows required clearances around the outdoor unit. It specifies minimum distances for all sides, with specific notes for clearances between multiple units.

Unit Dimensions

Table 1. UNIT DIMENSIONS

Unit Placement

IMPORTANT: This model is for check/expansion valve systems only. An indoor expansion valve approved for HFC-410A refrigerant must be ordered separately and installed prior to operation.

IMPORTANT: Direct exhaust vents from dryers, water heaters, and furnaces away from the outdoor unit to prevent corrosion and performance degradation.

Diagram: Figure 3. Placement

This diagram shows recommended placement of the 13ACX unit, advising to install it away from windows and noting the use of two 90° elbows in the line set to reduce vibration.

Slab Mounting

Install the unit level, or maintain a slope tolerance of 2 degrees away from the building structure.

Diagram: Figure 4. Slab Mounting

This diagram illustrates slab mounting for the 13ACX unit, showing the unit placed level or with a slight slope away from the building structure.

Line Set Installation

IMPORTANT: Refrigerant lines must not contact structure.

Diagram: Figure 5. Line Set Installation

These diagrams illustrate refrigerant line set installation and isolation techniques. They show transitions from vertical to horizontal runs, anchoring methods, and horizontal run support, emphasizing the need for insulation and non-contact with structure.

Refrigerant Piping

IMPORTANT: If the unit is matched with a system previously charged with mineral oil, or manufactured before January 1999, the coil and line set must be flushed. Failure to flush voids warranty.

WARNING: Use nitrogen for pressurizing at 1-2 psig. Recover refrigerant responsibly.

Diagram: Figure 6. Typical Liquid Line Filter Drier Installation

This diagram shows the typical installation of a liquid line filter drier in the liquid line between the outdoor unit's service valve and the indoor coil's metering device.

Table 2. REFRIGERANT LINE SET — INCHES (MM)

* Applicable to all minor revision numbers unless otherwise specified.

** Some applications may require a field-provided 1-1/8" to 7/8" adapter.

Flushing Existing Line Set and Indoor Coil

Diagram: Figure 7. Flushing Procedure

This diagram illustrates procedures for removing existing metering devices and connecting equipment for flushing the line set and indoor coil.

Brazing Procedures

Diagram: Figure 8. Brazing Setup

This diagram illustrates the setup for brazing refrigerant lines using a manifold gauge set, nitrogen flow, and service valve protection.

Diagram: Figure 9. Brazing Steps

This diagram shows the final steps of brazing refrigerant lines, including wrapping service valves with water-saturated cloths, allowing cooling, and preparing for the next step.

Installing Indoor Expansion Valve

Diagram: Figure 10. Expansion Valve Installation

These diagrams illustrate the installation of an indoor expansion valve and the sensing bulb, detailing connections and positioning for optimal performance.

Leak Test and Evacuation

Diagram: Figure 11. Leak Test Setup

This diagram illustrates the setup for leak testing the refrigerant system, showing the connection of the manifold gauge set, HFC-410A cylinder, and nitrogen cylinder.

Diagram: Figure 12. Evacuation Setup

This diagram illustrates the setup for system evacuation, showing the connection of the manifold gauge set, vacuum pump, micron gauge, and the process for achieving and maintaining vacuum levels.

Electrical

Diagram: Figure 13. Thermostat Installation

This diagram illustrates thermostat installation and basic wiring connections for the unit, including routing of low-voltage control wires.

Diagram: Figure 14. High Voltage and Field Control Wiring

This diagram illustrates high voltage and field control wiring connections between the thermostat, indoor unit, and outdoor unit, showing wire routing and connection points.

Using Manifold Gauge Set

Table 3. TORQUE REQUIREMENTS

Diagram: Figure 15. Service Valve Operation

These diagrams illustrate the operation of angle-type and ball-type service valves, including how to access service ports and the correct procedure for tightening service port caps and stem caps.

Checking and Adding System Refrigerant

The 13ACX unit is factory-charged for a 15-foot refrigerant line. Check and adjust charge per tables on the unit access panel. Detailed information is in the 13ACX Installation and Service Procedures manual.

Homeowner Information

CAUTION: Turn power OFF before servicing.

Outdoor Coil Maintenance: Contact dealer for inspection and service. Ensure no obstructions restrict airflow. Keep shrubbery trimmed and check for debris. Keep snow level below louvers.

IMPORTANT: Do not install sprinklers or soaker hoses where they could expose the unit to treated water, which can cause corrosion.

Routine Maintenance

Ensure peak performance by maintaining the system. Clogged filters and blocked airflow reduce efficiency.

NOTE: Filters and access panels must be in place during operation. Consult your dealer for filter information.

1. Locate your indoor unit's filter. Check monthly and clean or replace as needed.
2. Replace disposable filters with the same type and size.
3. The indoor evaporator coil has a drain pan. Have your dealer show you the drain line and how to check for obstructions.

Thermostat Operation

Refer to the ComfortSense® 7000 thermostat homeowner manual for operating instructions.

Preservice Check

Before calling for service, check:

• Thermostat settings.
• Electrical disconnect switches are ON.
• Blown fuses or tripped circuit breakers.
• Unit access panels are in place.
• Air filter is clean.

If service is needed, record the unit model number and have it ready.

Start-Up and Performance Checklist

This section provides checklists for verifying proper installation and performance.

Upflow Configuration Checklist (Figure 19): Includes checks for Duct System, Integrated Control, Voltage, Drain Line, External Static, Amps (Electric Heat, Blower), CFM, Temperature Drop (Cooling), Temperature Rise (Heating), and Thermostat settings. Diagrams are referenced for clarity.

Horizontal Configuration Checklist (Figure 20): Similar to the upflow checklist, adapted for horizontal installations.

Cooling Mode Checks

System Refrigerant Charge: Check subcooling and approach temperatures per manufacturer's information.

• Subcooling: Saturated Condensing Temperature (A) minus Liquid Line Temperature (B)
• Approach: Liquid Line Temperature (A) minus Outdoor Air Temperature (B)
• Indoor Coil Temperature Drop (18 to 22°F): Return Air Temperature (A) minus Supply Air Temperature (B)