INSTALLATION INSTRUCTIONS

General Information

The CX35 upflow evaporator coils are available cased only. The C35 coil is available cased or uncased and includes a factory-installed HFC-410A fixed orifice (RFC) metering device that must be replaced if the system match with the coil requires a field-installed check/expansion valve. The CX35 coil includes an externally equalized factory-installed HFC-410A check/expansion valve.

The coil drain pan has a maximum service temperature of 500°F. The drain pan must be at least 2 inches away from a standard gas-fired furnace heat exchanger and at least 4 inches away from any drum-type or oil-fired furnace heat exchanger. Closer spacing may damage the drain pan and cause a leak.

Refer to the Product Specification bulletin (EHB) for the proper use of these coils with specific furnaces, air handlers and line sets.

These instructions are intended as a general guide and do not supersede local or national codes in any way. Authorities who have jurisdiction should be consulted before installation.

Shipping and Packing List

Package 1 of 1 contains:

C35

• 1 - Evaporator coil
• 1 - Patch plate with nameplate label (uncased coils only)
• 1 - Metering device label (uncased coils only)

CX35

• 1 - Evaporator coil

Check the components for shipping damage; if found, immediately contact the last carrier.

Model Number Identification

The model number provides details about the coil's specifications. Below are the breakdowns for the C35 and CX35 series:

C35 Model Breakdown:

Unit Type: C = Indoor Coil - Upflow

Series: C35

Nominal Cooling Capacity:

• 18/24 = 1.5/2 tons
• 24 = 2 tons
• 30 = 2.5 tons
• 30/36 = 2.5/3 tons
• 36 = 3 tons
• 48 = 3.5/4 tons
• 49 = 4 tons
• 50/60 = 4/5 tons
• 60 = 5 tons

Metering Device: 2 = Factory-Installed RFC Orifice

Cabinet: F = Cased

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.)

CX35 Model Breakdown:

Unit Type: C = Indoor Coil - Upflow

Series: CX35

Refrigerant Type: X = HFC-410A

Nominal Cooling Capacity: (Same as C35)

Metering Device: 6 = Factory-Installed Check/Expansion Valve for HFC-410A Refrigerant (non-bleed port)

Cabinet: F = Cased

Cabinet Width: (Same as C35)

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

C35 Optional Adjustable Coil Adapter / Seal Applications

Diagrams illustrate the application of the adjustable coil adapter/seal for C35 uncased coils (models C35-18A through C35-62C and C35-60D and C35-62D). The adapter/seal is designed to fit between the uncased coil and the furnace plenum to ensure a proper seal and airflow.

Adjustable Coil Adaptor/Seal Dimensions

Front View: Shows dimensions for the adapter/seal, including an opening range of 14-1/2 (368) to 24-7/8 (632) inches in width and 9 (228) to 19-3/8 (492) inches in depth.

Side View: Shows dimensions for the adapter/seal, including a height of 19-3/4 (502) inches and an opening depth of 17-3/4 (451) inches.

Detail: The frame telescopes to accommodate various furnace openings. A tab is present that may be bent up 90° for centering smaller coils.

Releasing Air Charge

The C35 and CX35 coils are shipped with a 10 + 3 psi dry air holding charge. Puncture the suction line rubber plug to release the charge. Remove the rubber plug. Ensure that the coil is void of pressure.

Installation

Install the furnace or air handler according to the installation instructions provided with the unit.

Position the cased coil on top of the furnace or air handler cabinet and secure it using field-provided screws.

NOTE: If the coil is to be installed on an oil furnace, it may be necessary to install a field-installed transition between the furnace and the coil to prevent airflow restriction and possible damage to the coil drain pan. See the oil furnace installation instructions for details.

NOTE: The coil cabinet has six screw clearance holes which should be aligned with the furnace engagement holes. Secure the coil cabinet to the furnace or air handler using six field-provided #8 X 1" screws.

Refrigerant Line Connections

LINE SIZES

The refrigerant line sets should be sized according to the recommendations given in the air conditioner unit installation instructions. Use either Table 1 or 2 to determine correct braze connection sizes. A field-provided adapter may be required to match line set connections.

Table 1. Refrigerant Line Connections – Model C35

Replacement Parts

If replacement parts are necessary, order kit 69J46. The kit includes:

• 10 - Brass nuts for liquid line assemblies
• 20 - Teflon rings
• 10 - Liquid line orifice housings
• 10 - Liquid line assemblies

Figure 1. 69J46 Kit Components: This figure illustrates the components included in kit 69J46: liquid line orifice housings, Teflon rings, brass nuts, a piston retainer, a strainer, and liquid line assemblies (each including a strainer).

Brazing Guidelines

Use a silver alloy brazing rod (5 or 6 percent silver alloy for copper-to-copper connections or 45 percent silver alloy for copper-to-brass or copper-to-steel connections).

Before making brazed connections, place a field-provided heat shield, such as a wet rag, against the unit cabinet and around the piping stubs, expansion valve, and sensing bulb. The heat shield must be in place to prevent heat damage during brazing. See Figure 2.

Figure 2. Braze Refrigerant Lines: This diagram shows a wet rag placed against the coil cabinet and around the suction line connection to protect against heat damage during brazing. It also indicates to allow the pipe to cool before removing the wet rag.

Suction Line Connection

Use the following procedure to connect the suction line to the indoor coil:

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

C35 Suction Line Equalizer Fitting

Remove the copper flare seat bonnet if present from the male equalizer line fitting (see Figure 3).

Figure 3. C35 Suction Line Male Equalizer Line Fitting Modifications: This figure illustrates the removal of the copper flare seal bonnet from the male equalizer line fitting. It shows two options: either a flare seal cap or a flare nut, with instructions to remove and discard the flare seal bonnet if present.

C35 Liquid Line Connection

NOTE: C35 coils are shipped with a factory-installed HFC-410A fixed orifice (RFC) metering device. Some system matches with this coil require use of a check/expansion valve.

If the system match requires an HFC-410A check/expansion valve, the factory-installed refrigerant metering orifice must be removed and a check/expansion valve field-installed before the liquid line connections are made. The fixed orifice device must be removed BEFORE a check/expansion valve is installed if necessary. CX35 coils include a factory-installed HFC-410A check/expansion valve.

C35 Fixed Orifice Removal (If necessary)

1. Remove the coil access and plumbing panels.
2. Remove any shipping clamps that secure the liquid line and distributor assembly.
3. Using two wrenches, disconnect the liquid line stub from the orifice housing. Take care not to twist or damage the distributor tubes during this process.
4. Remove and discard the existing orifice, valve stem assembly (if present) and Teflon ring as illustrated in Figure 4.
5. Retain brass nut to be used later with the liquid line assembly.

Figure 4. Typical Fixed Orifice Removal: This diagram details the removal of a fixed orifice. It shows the components: distributor tubes, O-ring, strainer, liquid line stub, orifice housing, and a valve stem assembly. It indicates to remove and discard the valve stem assembly (if present) and the white Teflon seal.

C35 Expansion Valve / Liquid Line Installation

Some system matches for the C35 coil require a check/expansion valve. The expansion valve must be installed external to the indoor coil cabinet. Refer to the instructions provided with the expansion valve kit for proper installation of the valve and sensing bulb.

See the C35 Product Specification bulletin (EHB) for approved expansion valve match-ups and application information.

1. After the expansion valve, equalizer line, and sensing bulb have been installed per the kit instructions, braze the properly sized refrigerant piping into place. Carefully follow brazing guidelines and use wet rags to prevent heat damage.
2. Do not remove the water-saturated rags from the cabinet and piping until the piping has cooled completely.

NOTE: To prevent any possibility of water damage, properly insulate all parts of the expansion valve assembly that may sweat due to temperature differences between the valve and its surrounding ambient temperatures.

CX35 Liquid Line Connection

CX35 coils include a factory-installed HFC-410A check/expansion valve metering device.

Connect the properly sized field-provided liquid line to the liquid line stub as shown in Figure 5 using one of the following procedures:

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

OR

1. Cut the copper liquid line on a vertical or horizontal section. Use a field-provided coupling to join the properly sized field-provided refrigerant piping and the liquid line stub on the coil. Follow the brazing guidelines.
2. Do not remove the water-saturated rags from the cabinet and piping until the piping has cooled completely.

Figure 5. CX35 Liquid Line Connections: This figure shows two methods for connecting the liquid line: brazing a swedged connection or cutting the copper liquid line and using a coupling. It notes that the coupling can be used at either cut connection.

Leak Testing, Evacuating and Charging

Refer to the outdoor unit instruction for leak testing, evacuating and charging procedures. Always leak check entire system before charging.

Sealing Ducts

The coil cabinet MUST be sealed after installation to ensure against air leaks, which can impact system performance. The material, and method, used should be capable of enduring the range of temperature and humidity levels expected in the specific install location.

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

Condensate Drain Connections

MAIN DRAIN

Connect the main drain and route drain tubing downward to drain line or sump. Do not connect drain to a closed waste system. See Figure 6 for typical drain trap configuration.

Overflow Drain

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

CONDENSATE DRAIN RECOMMENDATIONS

The following practices are recommended to ensure better condensate removal:

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

Figure 6. Typical Main and Overflow Drain Installations: This diagram illustrates main and overflow drain installations. It shows recommendations for drain line routing, including the use of an overflow switch kit, vent extensions, and various trap configurations (P-trap, J-trap) with specific dimensions and slope requirements for drain lines. It also notes that for negative pressure coils, traps are required on all drain lines connected to the coil.

Blower Speed Selection

Proper air volume must be provided over the evaporator coil. Select a blower motor speed tap that will provide 400 ± 50 CFM per 12,000 Btuh of cooling capacity (wet coil). A static pressure reading must be taken to see if the pressure drop falls within the proper range.

To ensure accuracy, air must be read from below the coil and above the coil. See Figure 7 for an example to obtain an accurate reading.

Figure 7. Static Pressure Test: This figure illustrates the placement of test holes for static pressure measurement. It shows one hole drilled into the delta plate between the coil slabs and another into the duct above the top of the coil.

Blower Speed Adjustment Procedure:

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 top of the coil.
3. Connect the instrument for static pressure measurement hoses to the air entering side of coil. Insert the hoses so that 1/4" extends inside the duct or end seal. Seal around holes with Permagum®.
4. Turn on electrical power to the furnace and set the thermostat to initiate a cooling demand.
5. Tables 3 and 4 list air volumes and equivalent static pressure readings for these units. Observe the static pressure reading. If the reading is below the required air volume, increase the blower speed; if the reading is above the required air volume, decrease the blower speed. Refer to the furnace wiring diagram for blower speed settings.
6. When the required static pressure readings are obtained, remove the test hose lines and insert snap hole plugs into test holes.

Air Volume / Static Pressure Drop Tables

Table 3. Air Volume / Static Pressure Drop Across Coil – Model C35

Table 4. Air Volume / Static Pressure Drop Across Coil – Model CX35

Maintenance

This unit is equipped with an aluminum coil. Aluminum coils may be damaged by exposure to solutions with a pH below 5 or above 9. The aluminum coil should be cleaned using potable water at a moderate pressure (less than 50psi). If the coil cannot be cleaned using water alone, Lennox recommends use of a coil cleaner with a pH in the range of 5 to 9. The coil must be rinsed thoroughly after cleaning.

In coastal areas, the coil should be cleaned with potable water several times per year to avoid corrosive buildup (salt).

A trained technician or service agency must perform maintenance and service on equipment. At the beginning of each heating or cooling season, indoor coils should be cleaned.

Do not use hydrofluoric acid, alkaline, or similar chemicals on coils. These chemicals are not necessary to dissolve salt, and may damage the fin coating. Acid washes are used to dissolve oils and greases, which generally are not present on most installations.

Cleaning the Coil

Alkaline washes are useful for dissolving oxides such as zinc oxide, aluminum oxide, and iron oxide (rust). These three oxides are more corrosion-resistant than base metals, so dissolving or removing them will cause an increase in corrosion.

1. Remove the coil from the cabinet or plenum, and take the coil to an appropriate place to clean it.
2. Vacuum or brush the coil to remove matted and surface debris from the fins. Use vacuum attachments and /or brushes that are non-destructive to fins.
3. If oil deposits are present, spray the coil with a mild household liquid detergent to soften deposits. Do not leave the detergent on the coil for more than 10 minutes. Flush the coil thoroughly with potable water.

NOTE: For units in coastal regions, fresh water will dissolve away any salt deposits. (Wash coils with fresh water at least every six months.)

4. Spray the coil at a vertical angle of 30 to 45 degrees with a constant stream of water at moderate pressure. A pressure washer with a fan nozzle will work best. Do not spray the coil from a horizontal direction.
5. Direct the spray so that any debris is washed out of the coil and base pan. For most residential units, hot water is not necessary.

NOTE: Attempting to back flush from the inside of the coil will require removing parts from the unit, and it may be very difficult to flush the whole coil surface. Attempting to blow water through a coil will slow the water stream and reduce the flushing action of the outer fin surface.

6. Replace the coil into the cabinet or plenum. Ensure that you have followed the proper procedure for routing and securing the refrigerant tubing.