Lennox CX35 Series Coils Installation Instructions

General Information

This manual provides installation instructions for the Lennox CX35 Series Indoor Evaporator Coils. These coils are designed for use with R410A refrigerant and are available in cased configurations only.

The CX35 coil features a factory-installed HFC-410A check/expansion valve. The drain pan has a maximum service temperature of 500°F and requires specific clearance from furnace heat exchangers.

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

IMPORTANT: The Clean Air Act of 1990 bans the intentional venting of refrigerant. Approved methods of recovery, recycling, or reclaiming must be followed. Fines and/or incarceration may be levied for noncompliance.

CAUTION: Handle equipment with care to avoid personal injury from sharp sheet metal edges. Wear gloves and protective clothing.

NOTE: This unit CX35 is a PARTIAL UNIT AIR CONDITIONER and must be connected to other units complying with corresponding PARTIAL UNIT requirements.

WARNING: This appliance is not to be used by persons with reduced physical, sensory, or mental capabilities, or lack of experience and knowledge, unless supervised or instructed by a responsible person. Children should be supervised to ensure they do not play with the appliance.

The maximum altitude for application is 3200m above sea level.

Consult local or national codes and authorities having jurisdiction before installation.

Special procedures are required for cleaning the aluminum coil. Refer to page 5 for details.

Table of Contents

• Model Number Identification
• Shipping and Packing List
• Releasing Air Charge
• Installation
• Refrigerant Line Connections
• Leak Testing, Evacuating and Charging
• Condensate Drain Connections
• Blower Speed Selection
• Maintenance
• Decommissioning

Model Number Identification

The model number provides information about the unit's configuration:

• Unit Type: C = Indoor Coil - Upflow
• Refrigerant Type: X = HFC-410A
• Nominal Cooling Capacity: e.g., 18/24 = 1.5/2 tons, 30 = 2.5 tons, 36 = 3 tons, 48 = 3.5/4 tons, 50/60 = 4/5 tons, 60 = 5 tons
• Cabinet: F = Cased
• Series: CX35
• Metering Device: 6 = Factory-Installed Check/Expansion Valve for HFC-410A Refrigerant (non-bleed port)
• Cabinet Width: A = 14-1/2 in., B = 17-1/2 in., C = 21 in., D = 24-1/2 in.

Furnaces with the same cabinet width letter designation will physically match the corresponding indoor coil.

Shipping and Packing List

Package 1 of 1 contains: 1 - Evaporator coil.

Check components for shipping damage and contact the last carrier immediately if damage is found.

Releasing Air Charge

CAUTION: The coil is shipped pressurized with dry air. Pierce the rubber plug on the vapor line to relieve pressure before removing plugs.

NOTE: If no pressure is released, check the coil for leaks before proceeding.

The CX35 coils have a 10 ± 3 psi dry air holding charge. Puncture the suction line rubber plug to release the charge and remove the plug. Ensure the coil is void of pressure.

Installation

WARNING: Risk of explosion or fire. Can cause injury or death. Recover all refrigerant to relieve pressure before opening the system.

1. Install the furnace or air handler according to its installation instructions.
2. Position the cased coil on top of the furnace or air handler cabinet and secure it using field-provided screws.
3. NOTE: For oil furnaces, a field-installed transition may be necessary between the furnace and coil to prevent airflow restriction and potential damage to the coil drain pan. Refer to oil furnace installation instructions.
4. The coil cabinet has six screw clearance holes that should align with furnace engagement holes. Secure the coil cabinet using six field-provided #8 X 1" screws.

Refrigerant Line Connections

Refrigerant line sets should be sized according to the air conditioner unit installation instructions. Use Table 1 for correct braze connection sizes. A field-provided adapter may be required.

Replacement Parts

For replacement parts, order kit 69J46, which includes brass nuts, Teflon rings, liquid line orifice housings, and liquid line assemblies.

FIGURE 1. 69J46 Kit Components shows the parts included in the kit.

Brazing Guidelines

Use a silver alloy brazing rod (5 or 6 percent silver alloy for copper-to-copper, or 45 percent silver alloy for copper-to-brass/steel). Before brazing, place a field-provided heat shield (e.g., wet rag) against the unit cabinet and around piping stubs to prevent heat damage. See Figure 2.

Suction Line Connection:

1. Remove the rubber plug from the stubbed connection.
2. Position the refrigerant piping and make the brazed connection following brazing guidelines.
3. Do not remove water-saturated rags until piping has cooled completely.

CX35 Liquid Line Connection:

CX35 coils have a factory-installed HFC-410A check/expansion valve. Connect the field-provided liquid line to the stub as shown in Figure 3, using one of the following procedures:

1. Position the refrigerant piping and make the brazed connection following brazing guidelines.
2. Do not remove water-saturated rags until piping has cooled completely.

OR

1. Cut the copper liquid line and use a field-provided coupling to join the refrigerant piping and the coil's liquid line stub. Follow brazing guidelines.
2. Do not remove water-saturated rags until piping has cooled completely.

FIGURE 3. CX35 Liquid Line Connections illustrates the two cut connection options.

Leak Testing, Evacuating and Charging

Refrigerant system installations must comply with ASHRAE Standard 15.2. Refer to the outdoor unit instructions for leak testing, evacuating, and charging procedures. Always leak check the entire system before charging.

Sealing Ducts

WARNING: Ensure an airtight seal between the furnace bottom and the return air plenum. Use sealing strips, caulking, or equivalent methods. Return air must not be drawn from a room with a gas-fueled appliance or carbon monoxide-producing device.

The coil cabinet must be sealed to prevent air leaks, which affect system performance. The sealing material should withstand expected temperature and humidity levels.

Ensure the duct is secured and all joints are properly sealed to the coil cabinet flanges.

Condensate Drain Connections

IMPORTANT: After removing drain pan plugs, verify drain holes are clear of debris. Ensure no debris has fallen into the drain pan during installation.

Main Drain

Connect the main drain and route tubing downward to a drain line or sump. Do not connect to a closed waste system. See Figure 4 for typical drain trap configuration.

Overflow Drain

It is recommended that the overflow drain stub be connected to an overflow drain line. If not, it must be plugged with the provided cap.

Condensate Drain Recommendations

• Main and overflow drain lines should not be smaller than both drain connections at the drain pan.
• Overflow drain lines should run to an area where the homeowner will notice drainage.
• It is recommended that the overflow drain line be vented and a trap installed. Refer to local codes.

FIGURE 4. Typical Main and Overflow Drain Installations illustrates drain configurations, including the use of overflow switches and trap depths.

NOTE: When an air handler is located above a finished space, a secondary drain pan is required.

NOTE: For negative pressure coils (blower after coil), traps are required on all drain lines connected to the coil.

Drain lines should slope a minimum of one inch per 10 ft.

Blower Speed Selection

Proper air volume is essential for evaporator coil performance. Select a blower motor speed tap to provide 400 ± 50 CFM per 12,000 Btuh of cooling capacity (wet coil).

A static pressure reading must be taken to ensure the pressure drop is within the proper range. Air must be measured from below and above the coil (See Figure 5).

Procedure for Static Pressure Test:

1. Drill one 5/16" air test hole into the delta plate between the coil slabs.
2. Drill one 5/16" air test hole into the duct above the coil.
3. Connect the instrument hoses to the air entering side of the coil. Insert hoses 1/4" into the duct or end seal and seal around holes.
4. Turn on electrical power and set the thermostat to initiate cooling.
5. Refer to Table 3 for air volumes and equivalent static pressure readings. Adjust blower speed based on the reading: increase speed if below required air volume, decrease if above. Refer to the furnace wiring diagram for settings.
6. Once correct static pressure readings are obtained, remove test hoses and insert snap hole plugs.

FIGURE 5. Static Pressure Test shows the test hole locations.

Maintenance

NOTICE! Failure to follow instructions will cause damage to the unit.

This unit is equipped with an aluminum coil. Aluminum coils may be damaged by solutions with a pH below 5 or above 9. Clean the coil using potable water at moderate pressure (less than 50psi). If water alone is insufficient, use a coil cleaner with a pH between 5 and 9. Rinse the coil thoroughly after cleaning.

In coastal areas, clean the coil with potable water several times per year to prevent corrosive buildup.

A trained technician or service agency must perform maintenance. Clean indoor coils at the beginning of each heating or cooling season.

Do not use hydrofluoric acid, alkaline, or similar chemicals on coils, as they may damage the fin coating.

Cleaning the Coil

1. Remove the coil from the cabinet or plenum and take it to an appropriate place for cleaning.
2. Vacuum or brush the coil to remove debris from the fins using non-destructive attachments.
3. For oil deposits, spray with a mild household liquid detergent, let sit for no more than 10 minutes, then flush thoroughly with potable water.
4. NOTE: For coastal regions, fresh water dissolves salt deposits. Wash coils with fresh water at least every six months.
5. Spray the coil at a 30-45 degree vertical angle with a constant stream of water at moderate pressure. A pressure washer with a fan nozzle is recommended. Do not spray horizontally.
6. Direct spray to wash debris out of the coil and base pan. Hot water is not necessary for most residential units.
7. NOTE: Attempting to back flush from the inside may be difficult and may reduce flushing action.
8. Replace the coil into the cabinet or plenum, ensuring proper routing and securing of refrigerant tubing.

IMPORTANT: Ensure distributor lines are not rubbing or kinked. Use wire ties to secure tubes and prevent movement that could cause refrigerant tubing failure.

Use of Coil-Furnace System During Construction

Lennox does not recommend using coil-furnace systems during construction. Low return air temperatures, harmful vapors, and operation with clogged filters can damage the unit.

If used during construction, the following conditions must be met:

• A room thermostat must control the air handler; fixed jumpers are not allowed.
• An air filter must be installed and maintained.
• The air filter must be replaced upon construction completion.
• The evaporator coil, furnace supply fan assembly, and duct system must be thoroughly cleaned after construction.
• All coil and furnace operating conditions must be verified per these instructions.

Decommissioning

Technicians must be familiar with the equipment and procedures. Recover all refrigerants safely.

Before decommissioning:

• Take oil and refrigerant samples if analysis is required for re-use.
• Ensure electrical power is available.
• Become familiar with the equipment and its operation.
• Isolate the system electrically.
• Ensure mechanical handling equipment, personal protective equipment, and recovery equipment are available and used correctly. The recovery process must be supervised by a competent person.

Procedure:

1. Pump down the refrigerant system if possible.
2. If a vacuum is not possible, use a manifold to remove refrigerant from various system parts.
3. Place the cylinder on scales before recovery.
4. Start the recovery machine and operate per instructions.
5. Do not overfill cylinders (max 80% liquid charge).
6. Do not exceed cylinder working pressure.
7. Once cylinders are filled, remove them and the equipment promptly. Close all isolation valves.
8. Recovered refrigerant must not be charged into another system unless cleaned and checked.