Lennox Merit CBX25UHV, CBX25UHV-018, CBX25UHV-036, CBX25UHV-048, CBX25UHV-024 Installation Instructions Manual

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INSTALLATION

Dallas, Texas, USA

THIS MANUAL MUST BE LEFT WITH THE

HOMEOWNER FOR FUTURE REFERENCE

WARNING

Improper installation, adjustment, alteration, service or maintenance can cause personal injury, loss of life, or damage to property.

Installation and service must be performed by a licensed professional installer (or equivalent) or a service agency.

IMPORTANT

The Clean Air Act of 1990 bans the intentional venting of refrigerant (CFCs, HCFCs and HFCs) as of July 1, 1992. Approved methods of recovery, recycling or reclaiming must be followed. Fines and/or incarceration may be levied for noncompliance.

INSTRUCTIONS

Merit® CBX25UHV (-10) Series Units

AIR HANDLERS

507616-02 7/2018

Shipping and Packing List

Package 1 of 1 contains the following:

1 - Assembled air handler unit factory-equipped for up-flow or

horizontal air discharge application (includes up-flow 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 Merit® CBX25UHV air handler is designed for indoor installation only. As shipped, the unit is ready for installation in either up-flow or horizontal left-hand air discharge applications. Horizontal drain pan may be repositioned in the field to allow installation in the horizontal right-hand air discharge position. Various accessories are listed in the CBX25UHV Product

Specification bulletin.

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

Page 1

Merit® CBX25UHV Unit Dimensions – Up-flow – inches (mm)

NOTE - Unit is shipped configured for horizontal left-hand air discharge. Unit may be converted to horizontal right-

hand air discharge by repositioning horizontal drain pan. Dimensions remain the same in all configurations.

Page 2

Requirements

WARNING

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.

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

Select the 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 rating plate on the air handler for specific information.

IMPORTANT

Merit® CBX25UHV units include a factory-installed check/expansion valve which provides optimal refriger ant control and system performance with outdoor units of varying capacities. These units must be installed as part of a matched system as outlined in the CBX25UHV Product Specification bulletin.

CAUTION

As with any mechanical equipment, contact with sharp sheet metal edges can result in personal injury. Take care while handling this equipment and wear gloves and protective clothing.

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. This unit is provided with flanges for connecting the supply plenum.

WARNING

Danger of explosion. Keep flammable ma terials 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 installa tion. Failure to follow these instructions can result in death, explosion, or fire.

IMPORTANT

Excessive condensation may occur if the unit is installed in a warm, humid place. When the unit is installed in an unconditioned space, apply sealant around electrical wires, refrigerant piping and condensate lines at the point where they enter the cabinet. Apply sealant on the inside of the cabinet at the point where the electrical wires exit through the conduit open ing. Sealing the cabinet in this way prevents warm, moist, unconditioned air from entering the cabinet. Warm, moist air in the cabinet forms condensate on the cooler control box and electrical controls.

IMPORTANT

This unit is approved for installation clearance to com bustible material as stated on the unit rating plate. Ac cessibility 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 Merit® CBX25UHV 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.

Page 3

MERIT® CBX25UHV SERIES

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. 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.

Installation

Each unit consists of a blower assembly, refrigerant coil and controls in an insulated, galvanized steel factoryfinished 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

CBX25UHV units are equipped with a check/expansion valve, which is factory-installed internal to the cabinet.

UP-FLOW APPLICATION

1 - The air handler must be supported on the bottom only

and set on a solid floor or a field‐supplied support frame. Securely attach the air handler to the floor or support frame.

2 - If installing a unit in an up-flow application, remove the

horizontal drain pan.

IMPORTANT - The horizontal drain pan is not required in up-flow air discharge installations. It must be removed to provide the best efficiency and air flow.

3 - Place the unit in the desired location and properly

slope the unit (see page 8). Connect the return and supply air plenums as required using sheet metal screws.

4 - In applications that do not include a return air plenum,

install units on a stand that is raised at least 14” above the floor. This ensures proper air return.

HORIZONTAL APPLICATIONS

IMPORTANT

When removing the coil, there is a possibility of equip ment damage and personal injury. Be careful when re moving 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 re moving it.

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 which plugs are required for drain line

connections.

2 - With access door removed, remove drain line plugs to

install drain lines.

3 - Set unit so that it is sloped toward the end of the unit with

the drain pan (see figure 14).

4 - A typical horizontal configuration is shown in figure 2.

AIR FLOW

Drains

PLUGS

Figure 2. Left‐Hand Discharge Configuration

LEFT‐HAND DRAINS

HORIZONTAL DRAIN PAN

IMPORTANT - REMOVE PAN

FOR BEST EFFICIENCY

AND AIR FLOW.

UP-FLOW

DRAIN PAN

UP-FLOW DRAIN

CONNECTIONS (BOTH

SIDES; USE ONE SIDE

OR OTHER)

Figure 1. Up-flow Configuration

HORIZONTAL DRAIN CONNECTIONS (BOTH SIDES; NOT USED)

Page 4

5 - 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 3. Use sheet metal screws to connect the return and supply air plenums as required.

3 - Remove coil assembly, bottom drain pan and

horizontal drain pan as one unit from the air handler.

ANGLE IRON OR SHEET METAL ELECTRICAL INLET CLEAR

MAXIMUM 1/2” LONG SCREW

AIR FLOW

FRONT VIEW END VIEW

ANCE 4 IN. (102 MM)

Figure 3. Suspending Horizontal Unit

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 panels.

2 - Remove brackets securing pans to unit. See figure 4.

Figure 5. Remove Coil Assembly, Bottom Drain Pan

and Horizontal Drain Pan As A Unit

Figure 4. Remove Main Drain Pan Mounting

Brackets

4 - Remove the blow-off prevention brackets, top cap and

drip pan between slabs. Move the horizontal drain pan to the opposite side of the coil.

Figure 6. Remove Blow-Off Prevention Brackets,

Top Cap and Drip Pan

5 - Rotate drip pan 180º and reinstall on coil as shown by

the arrow above. Reinstall the top cap. Rotate the blow-off prevention brackets 180º and reinstall using the same screws. Use the correct mounting holes; the brackets must cover the hairpins. See figure 7.

Page 5

MERIT® CBX25UHV SERIES

Figure 7. Reinstall the Top Cap. Brackets Must

Cover the Hairpins

6 - Slide coil assembly, bottom drain pan and horizontal

drain pan as one unit back into the air handler.

Figure 9. Reinstall Brackets that Hold the Coil and

Horizontal Drain Pan in Place

Repositioning Black Box on Motor Module – -018,

-024 and -030 Units

When the horizontal drain pan is moved to the right side of the air handler, the black box on the back of the supply fan motor will prevent the insertion of the blower assembly back into the cabinet. The black box must be repositioned to overcome this issue.

Tools and Material Required:

1" or 2" putty knife and 1" wide double-sided tape.

8 - Arrange the blower assembly on a stable surface with

the motor facing up.

MOTOR

MODULE

Figure 8. Slide Coil Assembly, Bottom Drain Pan

and Horizontal Drain Pan Back Into the Air Handler

as a Unit

7 - Reinstall the brackets that hold the coil and horizontal

drain pan in place. See figure 9.

BLACK

BOX

Figure 10. Black Box in Factory Position on Motor

Module

Page 6

9 - The black box is fastened to the motor module at each

end with a strip of black double-sided tape. Starting at one end, slide the putty knife between the black box and the motor module. Carefully separate the black box from the motor module. Clean off any double-sided tape remaining on the motor module.

Figure 11. Black Box Separated from Motor Module

11 - Slide the blower assembly into the cabinet to confirm

clearance between the horizontal drain pan and the black box. Remove the blower assembly and relocate the black box if necessary to achieve clearance. Make note of the new position. Apply two new strips of double-sided tape to the black box and affix it to the module in the confirmed position.

12 -Slide the blower assembly back into the air handler

cabinet and install the two screws to secure the assembly to the cabinet. Plug the motor wires back into the motor and black box.

13 -Confirm that the black box is not touching the

horizontal drain pan.

10 - Cut a small piece of tape and apply it to the back of the

black box. This will be used to test the position of the black box. The goal is to raise the position of the box on the module. Position the black box onto the module higher than the original position.

Figure 12. Black Box Repositioned on Motor Module

Figure 13. Blower Assembly Installed in Air Handler

Cabinet with Required Clearance Between Horizontal Drain Pan and Motor Black Box

Page 7

MERIT® CBX25UHV SERIES

Condensate Drain

IMPORTANT

A field-fabricated secondary drain pan, with a drain pipe to the outside of the building, is required in all installa tions 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 ¾” NPT condensate drain connections.

SLOPING THE UNIT

Make sure the unit is sloped (similar to the slope shown in figure 14) (horizontal or up-flow) so that the drain pan will empty completely without water standing in the pan.

THIS CORNER SHOULD BE 5/8” (+/- 1/8”) HIGHER THAN DRAIN CORNER

INSTALL CONDENSATE DRAIN

The air handler is equipped with ¾” NPT condensate drain connections.

IMPORTANT

On some pans, the primary and secondary drain holes have knockouts. Confirm primary and secondary drains are open.

1 - CB25UHV units are equipped with a drain pan, which

includes green (main drain) and red (secondary drain) plugs. Unscrew the plugs to remove them before inserting condensate drain fittings.

ALL CBX25UHV MODELS

UNSCREW PLUGS

AND CONNECT

PROPERLY SIZED

FIELD-PROVIDED

FITTINGS AND

DRAIN LINES.

DRAIN PAN

GREEN MAIN

DRAIN PLUG

RED SECONDARY

DRAIN PLUG

DRAIN CORNER

Figure 14. Sloping the Unit for Proper Drainage

Figure 15. Drain Line Connections

Page 8

IMPORTANT

On units of this type, the blower “draws” rather than “blows” air through the coil. A trap must be installed in the primary (main) condensate drain line. The trap prevents the blower from drawing air through the drain lines into the air supply.

ABOVE

FINISHED

SPACE?

YES

NOTE - WHEN AN AIR HANDLER IS LOCATED ABOVE A FINISHED SPACE, THE SECONDARY DRAIN PAN MUST HAVE A LARGER FOOTPRINT THAN THE AIR HANDLER.

SECONDARY

DRAIN PAN

ALWAYS RUN A SECONDARY (OVERFLOW) DRAIN LINE. IF NOT POSSIBLE, INSTALL LOW VOLTAGE OVERFLOW SWITCH KIT. WIRE KIT TO SHUT DOWN COMPRESSOR PER INSTRUCTIONS.

USE TWO-PART 3/4” FEMALE SLIP INLET AND MALE ADAPTER

WHEN OBSTRUCTIONS PREVENT DIRECT THREADING OF OVERFLOW SWITCH.

SECONDARY (OVERFLOW) DRAIN LINE

LENNOX #

X3169

AIR HANDLER DRAIN PAN

MAIN DRAIN

WHEN A COIL IS LOCATED ABOVE A FINISHED SPACE, A 3/4” (19.1MM) SECONDARY DRAIN LINE MUST BE:

● CONNECTED TO SECONDARY DRAIN PAN

● CONNECTED TO THE SECONDARY

(OVERFLOW) DRAIN OUTLET OF THE AIR HANDLER DRAIN PAN.

CLEAN OUT

PRESS IN

(DO NOT GLUE)

VENT MUST EXTEND

ABOVE HEIGHT OF

COIL DRAIN PAN BY

TWO INCHES (51MM)

1” X 3/4” X 3/4”

REDUCING

TEE WITH

PLUG

LENNOX1 P-TRAP

49P66, J-TRAP #

91P90 OR ANY

PVC SCH 40 P- OR

J-TRAP 3/4”

VENT

2”

(51MM)

TRAP MUST BE DEEP ENOUGH TO OFFSET MAXIMUM STATIC DIFFERENCES — GENERALLY, TWO INCHES (51MM).

LENNOX P-TRAP 49P66 REQUIRES A LARGER INSTALLATION SPACE THAN THE J-TRAP 91P90.

PIPE NIPPLE PROVIDED IN BAG ASSEMBLY - SCH 80, 3/4” I. D. X 5” - 34K7401 (1): CUT THE PIPE

IN HALF AND USE IT TO ROUTE THE MAIN DRAIN.

Figure 16. Typical Main and Overflow Drain

2 - Install properly sized, field-provided connection

fittings and connect primary drain line to the main drain pan connection.

NOTE - When installing drain line connection fittings 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 secondary drain line is to be used, remove the

plug or the knockout and route the drain line so that water draining from the outlet will be easily noticed by the homeowner. Refer to local codes for drain trap requirements on the secondary drain line.

4 - Check again to ensure drain ports and drain pan are

free of all debris.

5 - 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.

6 - Install a 2” trap in the main (primary) drain lines as

close to the unit as practical (see figure 16). Make sure

TO APPROVED

DRAIN

DRAIN LINE SHOULD SLOPE A MINIMUM OF ONE INCH PER 10 FEET (25MM PER 3 METERS)

FOR NEGATIVE PRESSURE COILS (BLOWER AFTER COIL), A TRAP IS REQUIRED ON THE MAIN DRAIN LINE CONNECTED TO COIL. SEE LOCAL CODES FOR TRAP REQUIRE MENTS ON SECONDARY DRAINS.

TRAP DEPTH

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 16. An extremely long horizontal run may require an oversized drain line to eliminate air traps.

NOTE - Do not operate air handler without a trap in the main (primary) drain. The condensate drain is on the negative pressure side of the blower; therefore, air being pulled through the condensate line will not allow positive drainage without a proper trap.

7 - 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.

Page 9

MERIT® CBX25UHV SERIES

TEST CONDENSATE DRAIN

Test the drain pan and drain line after installation:

1 - Pour several quarts of water into drain pan. Use

enough water to fill both the drain trap and the line.

2 - Check the installed drain pan. Drain pan must drain

completely. Drain line fittings must not leak. Water must drain 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 supply plenum.

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.

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.

FILTERS

A filter is provided. Table 1 lists the filter size for each unit.

Table 1. Unit Air Filter Size Chart

Model Filter Size

-018 12” x 20” x 1 11.50” x 19.50” x .75”

-024 and -030 15” x 20” x 1 14.50” x 19.50” x .75”

-036 18” x 20” x 1 17.50” x 19.50” x .75”

-042, -048 and -060 18” x 24” x 1 17.50” x 23.50” x .75”

Actual Minimum

Filter Size

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.

FIELD-FABRICATED RETURN AIR DUCT FLANGE FOR HORIZONTAL APPLICATIONS

A return air duct system is recommended, but not factory-provided. If the unit is installed in a confined space or closet, run a full-size return connection to a location outside the closet.

Cabinet and Duct Flange

CABINET DOOR FLANGE

1−1/2

(38)

DUCT FLANGE

3/4

(19)

1−1/2(38)

3/4

(19)

”A”

BRAKE DOWN 90 DEGREES

1/2

(13)

UNIT SIZE

−018 14−7/8 (378)

−024 & −030 18−3/8 (467)

−036 to −060 21−3/4 (552)

3/4

(19)

1/4 (6) DIA.

2−HOLES

”A”

BOTTOM OF CABINET

DUCT ADAPTER

3/4

(19)

1−1/2

(38)

IMPORTANT

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, result ing in an increase in the number of service calls.

Before using any filter with this system, check the spe cifications provided by the filter manufacturer against the data given in the appropriate Lennox Product Specifica tions bulletin. Additional information is provided in Ser vice and Application Note ACC002 (August 2000).

Figure 17. Cabinet and Duct Flange

Brazing Refrigerant Lines

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

IMPORTANT

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

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

Page 10

WARNING

Polyol ester (POE) oils used with HFC-410A refrigerant absorb moisture very quickly. It is very important that the refrigerant system be kept closed as much as possible. DO NOT remove line set caps or service valve stub caps until you are ready to make connections.

WARNING

Danger of fire. Bleeding the refrigerant charge from only the high side may result in the low side shell and suction tubing being pressurized. Application of a brazing torch while pressurized may result in ignition of the refrigerant and oil mixture - check the high and low pressures before unbrazing.

WARNING

When using a high pressure gas such as dry nitrogen to pressurize a refrigeration or air conditioning system, use a regulator that can control the pressure down to 1 or 2 psig (6.9 to 13.8 kPa).

CAUTION

Brazing alloys and flux contain materials which are hazardous to your health.

Avoid breathing vapors or fumes from brazing operations. Perform operations only in well ventilated areas.

Wear gloves and protective goggles or face shield to protect against burns.

Wash hands with soap and water after handling brazing alloys and flux.

IMPORTANT

To prevent the build-up of high levels of nitrogen when purging, be sure it is done in a well ventilated area. Purge low pressure nitrogen (1 to 2 psig) through the refrigerant piping during brazing. This will help to prevent oxidation and the introduction of moisture into a system.

NOTE - When installing refrigerant lines longer than 50 feet, see the Lennox Refrigerant Piping Design and Fabrication Guidelines, CORP. 9351-L9, or contact Lennox Technical Support Product Applications for assistance. To obtain the correct information from Lennox, be sure to communicate the following information: Model and capacity.

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 a direct path, 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 - 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.

NOTE - Place wet rags against piping plate and around suction line connections.

4 - Connect the suction and liquid lines to the evaporator coil.

Take care to protect the cabinet and internal components as detailed in figure 18.

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 - Allow refrigerant pipes to cool to room temperature. 7 - Reinstall the rubber grommets into the refrigerant piping

panel.

NOTE - Make sure expansion valve capillary tube is not touching metal edges or copper tubing.

8 - Make sure outdoor unit has been placed according to the

Installation Instructions and is connected to the refrigerant lines.

Page 11

MERIT® CBX25UHV SERIES

PLEASE READ IMPORTANT ISSUES CONCERNING BRAZING

OPERATIONS ON PREVIOUS PAGES BEFORE PROCEEDING.

NOTE - REFER TO OUTDOOR UNIT INSTALLATION INSTRUCTIONS FOR REFRIGERANT PIPING SIZE REQUIREMENTS.

NOTE - Use silver alloy brazing rods with five or six percent minimum silver alloy for copper-to-copper brazing, 45 percent alloy for copper-to-brass and copper-to-steel brazing.

REMOVE ACCESS PANEL

REMOVE RUBBER PLUG FROM BOTH LIQUID

AND SUCTION LINES

NOTE - CBX25UHV SERIES UNITS USE NITROGEN OR DRY AIR AS A HOLDING CHARGE. IF THERE IS NO PRESSURE WHEN THE RUBBER PLUGS ARE REMOVED, CHECK THE COIL FOR LEAKS BEFORE INSTALLING.

EITHER REMOVE OR PUSH PIPE WRAPPING BACK

THROUGH HOLE IN PIPING PLATE BEFORE LINE SET CONNECTION AND BRAZING.

PIPING PLATE

LOW

HIGH

CONNECT PIPES

NOTE - REFRIGERANT LINE SETS SHOULD BE ROUTED TO ALLOW FILTER ACCESSIBILITY.

PLACE A WET RAG AGAINST PIPING

PLATE AND AROUND THE SUCTION LINE CONNECTION. A

BRAZE CONNECTION. ALLOW PIPE TO

COOL BEFORE REMOVING WET RAG FROM CTXV SENSING BULB AND PIPING PANEL AREA.

REPEAT PREVIOUS PROCEDURE FOR

LIQUID LINE.

CONNECT GAUGES AND

START NITROGEN FLOW

FLOW REGULATED NITROGEN (AT 1 TO 2 PSIG) THROUGH THE REFRIGERATION GAUGE SET INTO THE VALVE STEM PORT CONNECTION ON THE OUTDOOR UNIT LIQUID LINE SERVICE VALVE AND OUT OF THE VALVE STEM PORT CONNECTION ON THE SUCTION SERVICE VALVE.

REFER TO INSTRUCTIONS PROVIDED WITH OUTDOOR UNIT FOR LEAK TESTING, EVACUATING AND CHARGING PROCEDURES

NITROGEN

Figure 18. Brazing Connections

Page 12

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.

WARNING

There must be an air-tight 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.

IMPORTANT

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

Electrical Connections

WARNING

Electric Shock Hazard.

Can cause injury or death.

Foil‐faced insulation has conductive characteristics sim ilar to metal. Be sure there are no electrical connections within a ½” 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 person al injury or death.

WARNING

Electric Shock Hazard. Can cause injury or death. Unit must be grounded in accordance with national and local codes.

Line voltage is present at all components when unit is not in operation on units with single‐pole contactors. Disconnect all remote electric power supplies before opening access panel. Unit may have multiple power supplies.

WARNING

Electric shock hazard! - Disconnect all power supplies before servicing.

Replace all parts and panels before op erating.

Failure to do so can result in death or elec trical shock.

WARNING

Run 24V Class II wiring only through specified low voltage opening. Run line voltage wiring only through specified high voltage opening. Do not combine voltage in one opening.

WARNING

Electrically ground air handler. Connect ground wire to ground terminal marked “GND”.

Failure to do so can result in death or elec trical shock.

● Wiring must conform to the current National Electric

Code ANSI/NFPA No. 70, or Canadian Electric Code Part I, CSA Standard C22.1, and local building codes. Refer to following wiring diagrams. See unit nameplate for minimum circuit ampacity and maximum over-current protection size.

Page 13

MERIT® CBX25UHV SERIES

● 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. Select the proper supply circuit conductors in accordance with tables 310-16 and 310-17 in the National Electric Code, ANSI/NFPA No. 70 or tables 1 through 4 in the Canadian Electric Code, Part I, CSA Standard C22.1.

● 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.

● Separate openings have been provided for 24V low

voltage and line voltage. Refer to the dimension illustration of specific location.

● This unit is provided with holes for conduit. Use

provided caps to seal holes not used.

● Typical unit wiring (as well as wiring of optional

field-installed electric heat) is given in figure 21. Refer to the instructions provided with the electric heat section for proper installation.

● See figure 22 for typical low voltage field wiring

connections.

WARNING

USE COPPER CONDUCTORS ONLY

LOW VOLTAGE TERMINAL STRIP

Figure 19. Electrical Connections

(Upflow Configuration)

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 black transformer leads from the 240-volt terminal on the transformer to the 208-volt terminal on the transformer. See figure 20.

208 / 240 VOLT TRANSFORMER

PRIMARY SECONDARY

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.

240 Volts

208 Volts

Figure 20. Converting Unit from 240 VAC to 208 VAC

Page 14

SYSTEM FIELD JUMPERS SINGLE STAGE AIR CONDITIONER NEED ALL TWO−STAGE AIR CONDITIONER REMOVE Y1 TO Y2 SINGLE STAGE HEAT PUMP REMOVE R TO O TWO−STAGE HEAT PUMP REMOVE Y1 TO Y2 AND R TO O TWO−STAGE ELECTRIC HEAT REMOVE W1 TO W2 TO ACTIVATE DEHUMIDIFICATION REMOVE R TO DS

WARNING

USE COPPER CONDUCTORS ONLY

220

208/240

VOLTAGE

BY OTHERS

PART NO. 104796−01

CIRCUIT BREAKER 2

L1B

L2B

L1A

L2A

GND

14 YEL

14 BLK

14 BLK L1

14 YEL L2

208V 240V

TO BLOWER

GROUND LUG

14 RED L2

14 YEL

COM

14 BLK

GND.

18 YEL

12 BLK

CIRCUIT BREAKER 1

18 BLUE L2

18 RED

WIRING DIAGRAM − ELECTRIC HEAT

SEQ 2

12 YEL 12 YEL

SEQ 1

65432

18 BLACK L2

18 WHITE

18 BLK

18 GRN

GRD

6 4

1 2 3 4 5

18 WHT

1 2 3 4 5

MOTOR

6 7 8

9 10 11 12 13 14 15 16

18 BLK

12 BLK 12 BLK

12 YEL 12 YEL

18 WHITE

18 WHITE 18 YELLOW

18 WHITE

18 ORANGE

18 PURPLE

18 WHITE 18 WHITE

12 BLK

12 BLK 14 RED

14 YEL

14 RED

18 BLUE

18 BLU

5 3

18 BLU

18 WHITE L2

18 RED

W1 W2

18 BLK

12 BLK 12 BLK

18 BLU

18 BLUE/WHITE

LS1

LS2

***SEQ3

1 3

18 RED

18 BLUE

18 PRPLE

18 ORG

***SEQ4

6−PIN

18 YEL

18 WHITE

LS3

LS4

PLUG

18 YEL

2nd STAGE

HE4

1st STAGE

HE2

18 BLK

18 GRN

HE1

HEATERS USED

5 KW = HE1

7.5 & 10 KW = HE1 & HE2

HE3

15 KW = HE1,HE3 & HE4

TB = TERMINAL BLOCK CB = CIRCUIT BREAKER SEQ = SEQUENCER GND = GROUND LUG LS = LIMIT SWITCH

POWER (FACTORY WIRED) POWER (FIELD WIRED) CONTROL (FACTORY WIRED) CONTROL (FIELD WIRED)

CONTROL CIRCUIT WIRING TO BE 24 VOLT, N.E.C. CLASS 2

PLUG PIN LOCATION

4156

TD = TIME DELAY (OPT .)

TR = TRANSFORMER 1 2 3 4

5 6 7 8 9

10 11

BR = BLOWER RELAY

MTR = BLOWER MOTOR

CAP = MOTOR CAPACITOR

GND = GROUND CONNECTION

*** SEQUENCER USED: WIRED AS SHOWN RELAY USED: WIRED PER RELAY POLE TO BREAK CIRCUIT NO DEVICE PRIOR TO 10−15−2014

WIRING DIAGRAM: NO HEAT

WIRE NUTS

BY OTHERS

CIRCUIT BOARD

13 14 15

14 BLK

6−PIN

PLUG

14 YEL(240V)

14 WHT(120V)

THREE POLE SEQUENCER

TIMING − SEC ON 1−20 20−60 20−60

TWO POLE SEQUENCER

TIMING − SEC

ON 30−90

6514

30−90

L2 OR NEUT.

14 GRN

GRD

(OPT.) (OPT.)

OFF 40−110 1−30 1−30

OFF 1−30 1−30

15 AMP

SUPPLY

VOLTAGE

Figure 21. Typical Wiring Diagram — CBX25UHV Air Handler with Electric Heat

GND

Page 15

MERIT® CBX25UHV SERIES

Figure 22. Low Voltage Connections (Variable-Speed Motor)

WARNING

USE COPPER CONDUCTORS ONLY

Page 16

BDC3 Blower Control

JP1 15 PIN

PLUG (BOARD

TO MOTOR)

QC1

24V ACCESSORY

CONTACTS –

RATED FOR 1 AMP

OR LESS

OPERATIONAL SELECTOR PINS (AFFECTS BOTH

HEATING AND

COOLING MODES)

Figure 23. BDC3 Variable Speed Control Selections

SERVICE

24V/1A

QC2

ADJUST HEAT COOL DELAY CFM RUN

HEATING SPEED SELECTOR PINS

COOLING SPEED

SELECTOR PINS

Merit® CBX25UHV units are equipped with a variable-speed motor that is capable of maintaining a specified CFM throughout the external static range. A particular CFM can be obtained by positioning jumpers (COOL, HEAT, and ADJUST) on the BDC3 control.

The jumpers are labeled 1, 2, 3, and 4. This indicates the selected air volume (CFM). The ADJUST jumper is labeled Test, -, +, and Norm. The - and + pin settings are used to add or subtract a percentage of the CFM selected. The Test jumper is used to operate the motor in the test mode. The delay jumper controls the timing pattern in which the fan delay occurs.

Figure 23 illustrates the BDC3 control. Use either table 5 on page 19, or table 6 on page 19, to determine the correct air volume for heat and cool speed taps.

Diagnostic LEDs located on the BDC3 control to assist in servicing the unit. Read the jumper settings section before adjusting blower speed. Refer to figure 23 on page 17 for identification.

NORM +

TEST

JP1

4 3 2 1

FAN DELAY

SELECTOR PINS

4 3 2 1

DIAGNOSTIC

LEDS

Adjusting the Blower Speed

Diagnostic LEDs

1 - RUN LED indicates there is a demand for the blower

motor to run.

2 - CFM LED indicates the cubic feet per minute at which

the unit is operating. The light flashes once for approximately every 100 CFM. For example, if the unit is operating at 1000 CFM, CFM LED will flash 10 times. If the CFM is 1150, CFM LED will flash 11 full times plus one fast or half flash.

At times, the light may appear to flicker or glow. This is normal and occurs when the control is communicating with the motor between cycles.

Move the jumper pins to select the blower speed needed to meet application CFM requirements.

Page 17

JUMPER SETTINGS

IMPORTANT

Before changing jumper setting, make sure the motor has completely stopped. Any jumper setting change will not take place while the motor is running.

Table 2 lists the recommended factory blower speed tap selections for Merit® CBX25UHV series units. These settings are for nominal tonnage match-ups with the Merit CBX25UHV. When matched with other sizes, it is recommended that the CFM be adjusted to provide approximately 400 CFM per ton.

Table 2. Recommended Blower Speed Taps

Speed Tap Selection

Air Handler

CBX25UHV018

CBX25UHV024

CBX25UHV030

CBX25UHV036

CBX25UHV042

CBX25UHV048

CBX25UHV060

NOTES -

1 - Condensing Unit 2 - Heat Pump 3 - Condensing Unit with electric heat only 4 - Heat Pump with electric heat

* Minimum setting for heat

To change jumper positions, gently pull the jumper off the pins and insert it onto the desired set of pins. The following section outlines the different jumper selections available and conditions associated with each one as illustrated in figure 23.

After the CFM for each application has been determined, the jumper settings must be adjusted to reflect those given in the appropriate tables on the following pages. From the tables, determine which row of CFM volumes most closely matches the desired CFM. Once a specific row has been chosen (+, NORMAL, or -), CFM volumes from other rows cannot be used. Below are descriptions of the jumper selections.

ADJUST JUMPER

The ADJUST pins allow the motor to run at normal speed, slightly higher (approximately 10%) than normal speed, or slightly lower (approximately 10%) than normal speed. The tables on the following pages list three rows (+, NORMAL, and -) with their respective CFM volumes. Notice in table 3, for example, that the normal adjustment setting for heat

Cooling Heating*

Note 1 - Note 2 - Note 3 - Note 4 -

COOL PIN #2

COOL PIN #3

COOL PIN #3-

COOL PIN #2

COOL PIN #3

COOL PIN #3-

HEAT PIN #2

HEAT PIN #2+

HEAT PIN #2

MERIT® CBX25UHV SERIES

HEAT PIN #2

HEAT PIN #2+

HEAT PIN #2

speed position #4 is 1000 CFM. The + adjustment setting for that position is 1080 CFM and for the - adjustment setting is 910 CFM. After the adjustment setting has been determined, choose the remaining speed jumper settings from those offered in the table in that row.

The TEST pin is available to bypass the BDC3 control and run the motor at approximately 70% to test that the motor is operational. This is beneficial primarily in troubleshooting. G must be energized for motor to run.

COOL JUMPER

The COOL jumper is used to determine the CFM during either cooling or heat pump operation without a call for electric heat. These jumper selections are activated for cooling when Y2 and DS terminals in the Merit CBX25UHV are energized. The are activated for heating when Y2 is energized.

Applications without the Lennox ComfortSense® 7000 thermostat will provide 70% of the COOL CFM during first-stage cooling for two-stage outdoor units. 100% of COOL speed is provided for systems with a single-stage outdoor unit.

Applications with the Lennox ComfortSense® 7000

Table 3. Merit® CBX25UHV‐018 Air Handler Performance (0 through 0.80 in. w.g. [0 — 200 Pa] External Static Pressure Range)

thermostat, but no demand for de-humidification will operate as follows: during a first-stage cooling call (two-stage outdoor unit), the air volume is 70% of the COOL jumper selection. This arrangement provides for additional dehumidification during standard first-stage cooling. See the tables that follow for various scenarios concerning use of the ComfortSense® 7000 thermostat and the Merit® CBX25UHV series unit.

For applications with Harmony III® zone control, the air handler CFM volume is determined by the Harmony III control center. The minimum blower speed is predetermined at 250 CFM for -018, -024, -030 and -036 units and 450 CFM for -042, -048 and -060 units. This

speed is not adjustable. See footnotes in the blower performance tables.

With the thermostat set for Continuous Fan and without a call for heating or cooling, the Merit® CBX25UHV provides 50% of the COOL CFM selected.

NOTE - For two-stage heat pumps, air handler will operate at 70% of the COOL selection until supplemental electric heat is demanded. At that time, the air handler will operate at the selected HEAT speed. This arrangement provides warmer supply air during second-stage heating.

Jumper Speed Positions

“ADJUST”

Jumper

Setting

cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm

+ 470 670 890 1080 350 470 620 760 470 675 890 1090

NORM 440 615 810 1000 350 450 560 700 435 610 815 1020

– 400 560 730 910 350 420 520 650 400 575 725 915

NOTES  The effect of static pressure, filter and electric heater resistance is included in the air volumes listed. First-stage cooling air volume is 70% of COOL (second-stage) speed setting. Continuous blower speed is approximately 50% of COOL speed setting. Lennox Harmony III™ Zoning System applications  minimum blower speed is 250 cfm.

Table 4. Merit® CBX25UHV‐024 Air Handler Performance (0 through 0.80 in. w.g. [0 — 200 Pa] External Static Pressure Range)

“ADJUST”

Jumper

Setting

cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm

+ 470 690 900 1120 350 470 625 775 480 670 890 1125

“HEAT” Speed First-Stage “COOL” Speed Second-Stage “COOL” Speed

1 2 3 4 1 2 3 4 1 2 3 4

Jumper Speed Positions

“HEAT” Speed First-Stage “COOL” Speed Second-Stage “COOL” Speed

1 2 3 4 1 2 3 4 1 2 3 4

NORM 430 640 810 1020 330 450 580 720 430 605 820 1020

– 410 550 720 900 300 405 505 650 390 545 740 930

Page 18

Table 5. Merit® CBX25UHV‐030 Air Handler Performance (0 through 0.80 in. w.g. [0 — 200 Pa] External Static Pressure Range)

Jumper Speed Positions

“ADJUST”

“HEAT” Speed First-Stage “COOL” Speed Second-Stage “COOL” Speed

Jumper

Setting

1 2 3 4 1 2 3 4 1 2 3 4

cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm

+ 650 900 1100 1320 430 600 740 920 650 875 1100 1330

NORM 590 795 1000 1200 390 550 680 830 580 800 1000 1200

– 520 730 895 1075 340 475 620 750 500 700 900 1090

Table 6. Merit® CBX25UHV‐036 Air Handler Performance (0 through 0.80 in. w.g. [0 — 200 Pa] External Static Pressure Range)

Jumper Speed Positions

“ADJUST”

“HEAT” Speed First-Stage “COOL” Speed Second-Stage “COOL” Speed

Jumper

Setting

1 2 3 4 1 2 3 4 1 2 3 4

cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm

+ 880 1115 1345 1435 615 770 930 1090 880 1110 1340 1435

NORM 800 1010 1215 1425 555 695 845 990 795 1005 1215 1420

– 715 905 1095 1275 505 625 755 885 715 905 1090 1280

Table 7. Merit® CBX25UHV‐042 Air Handler Performance (0 through 0.80 in. w.g. [0 — 200 Pa] External Static Pressure Range)

Jumper Speed Positions

“ADJUST”

“HEAT” Speed First-Stage “COOL” Speed Second-Stage “COOL” Speed

Jumper

Setting

1 2 3 4 1 2 3 4 1 2 3 4

cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm

+ 1115 1345 1560 1800 800 960 1120 1265 1130 1360 1580 1800

NORM 1025 1215 1415 1630 730 870 1020 1150 1040 1240 1450 1640

– 925 1110 1280 1460 650 790 915 1050 950 1120 1290 1470

Page 19

MERIT® CBX25UHV SERIES

Table 8. Merit® CBX25UHV‐048 Air Handler Performance (0 through 0.80 in. w.g. [0 — 200 Pa] External Static Pressure Range)

Jumper Speed Positions

“ADJUST”

“HEAT” Speed First-Stage “COOL” Speed Second-Stage “COOL” Speed

Jumper

Setting

1 2 3 4 1 2 3 4 1 2 3 4

cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm

+ 1450 1670 1880 2340 1050 1200 1340 1650 1440 1670 1950 2340

NORM 1340 1520 1730 2100 950 1100 1230 1520 1325 1530 1740 2150

– 1210 1390 1570 1915 850 1000 1110 1375 1200 1380 1600 1950

Table 9. Merit® CBX25UHV‐060 Air Handler Performance (0 through 0.80 in. w.g. [0 — 200 Pa] External Static Pressure Range)

Jumper Speed Positions

“ADJUST”

“HEAT” Speed First-Stage “COOL” Speed Second-Stage “COOL” Speed

Jumper

Setting

1 2 3 4 1 2 3 4 1 2 3 4

cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm cfm

+ 1700 1930 2120 2275 1225 1410 1530 1690 1720 1930 2140 2270

NORM 1570 1760 1925 2100 1120 1260 1400 1540 1580 1765 1970 2100

– 1420 1595 1760 1920 1015 1160 1275 1390 1430 1625 1780 1890

Table 10. Merit® CBX25UHV, Thermostat and Single-Stage Outdoor Unit Operating Sequence

Operating Sequence System Demand System Response

System Condition

NO CALL FOR DEHUMIDIFICATION

Normal Operation 1 On On On Acceptable 24 VAC High 100%

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation

Dehumidification Call 2 On On On Demand 0 VAC High

PRECISION MODE (operates independent of a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable 24 VAC High 100%

Dehumidification Call 2 On On On Demand 0 VAC High

Dehumidification Call ONLY

* During dehumidification, cooling air handler speed is as follows: 70% of COOL cfm for 018, 024, 030; 65% for 036; 60% for 042, 048 and 060 units. ** Thermostat will maintain the room temperature up to 2°F (1.2°C) cooler than the room thermostat setting in precision mode.

Step

1 On On On Acceptable 24 VAC High 100%

1 On On On Demand 0 VAC High

Jumpers at indoor unit with a single stage outdoor unit With Condensing unit - Y1 to Y2 and R to O With Heat Pump - Y1 to Y2

Thermostat Demand Relative Humidity

Y1 Y2 O G W1 W2 Status D

Com

pressor

Air

Handler

CFM

(COOL)

60%/65

70%*

60%/65%

70%*

60%/65%

70%*

Comments

Compressor and indoor air handler fol low thermostat demand

Thermostat energizes Y1 and de-ener gizes D on a call for dehumidification

Dehumidification mode begins when hu midity is greater than set point

Thermostat will try to maintain room hu midity setpoint by allowing the room space to maintain a cooler room ther mostat setpoint**

Page 20

Table 11. Merit® CBX25UHV, Thermostat and Two‐Stage Outdoor Unit Operating Sequence

Operating Sequence System Demand System Response

Thermostat Demand Relative Humidity

System Condition

NO CALL FOR DEHUMIDIFICATION

Normal Operation

- Y1

Normal Operation

- Y2

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable 24 VAC Low 70%

Dehumidification Call

PRECISION MODE (operates independent of a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable 24 VAC Low 70%

Dehumidification Call

Dehumidification Call ONLY

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On On On On Acceptable 24 VAC High 100%

Dehumidification Call

PRECISION MODE (operates independent of a Y1 thermostat demand)

Normal Operation 1 On On On On Acceptable 24 VAC High 100%

Dehumidification Call

Dehumidification Call ONLY

Step

1 On On On Acceptable 24 VAC Low 70%

2 On On On On Acceptable 24 VAC High 100%

Room Thermostat Calls for First-Stage Cooling

2 On On On On Demand 24 VAC High

2 On On On On Demand 0 VAC High

1 On On On On Demand 0 VAC High

Room Thermostat Calls for First- and Second-Stage Cooling

2 On On On On Demand 0 VAC High

1 On On On On Demand 0 VAC High

Jumpers at indoor unit with a two-stage outdoor unit With Condensing unit - Y2 and R to O With Heat Pump - none

Com

pressor

Air

Handler

CFM

(COOL) CommentsY1 Y2 O G W1 W2 Status D

60%/65%

70%*

60%/65%

70%*

60%/65%

70%*

60%/65%

70%*

60%/65%

70%*

60%/65%

70%*

Compressor and indoor air handler follow thermostat demand

Thermostat energizes Y2 and de-ener gizes D on a call for dehumidification

Dehumidification mode begins when hu midity is greater than set point

Thermostat will try to maintain room hu midity setpoint by allowing the room space to maintain a cooler room thermo stat setpoint**

Thermostat energizes Y2 and de-ener gizes D on a call for dehumidification

Dehumidification mode begins when hu midity is greater than set point

Thermostat will try to maintain room hu midity setpoint by allowing the room space to maintain a cooler room thermo stat setpoint**

HEAT JUMPER

The HEAT jumper is used to determine CFM during electric heat operation only. These jumper selections are activated only when W1 is energized.

DELAY JUMPER

The DELAY jumper is used to set the specific motor fan operation during cooling mode. Depending on the application, one of four options may be chosen by moving the jumper to the appropriate set of pins.

#1 Pins Jumpered

A- Motor runs at 100% until demand is satisfied.

B- Once demand is met, motor ramps down to stop.

A B

100% CFM

COOLING DEMAND

OFFOFF

#2 Pins Jumpered

A- Motor runs at 100% until demand is satisfied.

Page 21

B- Once demand is met, motor runs at 100% for 60

seconds.

C- Motor ramps down to stop.

100% CFM (60 seconds)

OFF

100% CFM

COOLING DEMAND

#3 Pins Jumpered

A- Motor runs at 82% for approximately 7-1/2 minutes. If

demand has not been satisfied after 7-1/2 minutes -

B- Motor runs at 100% until demand is satisfied.

C- Once demand is met, motor ramps down to stop.

OFF

7 1/2 MIN

82%CFM

100% CFM

COOLING DEMAND

MERIT® CBX25UHV SERIES

#4 Pins Jumpered

A- Motor runs at 50% for 30 seconds.

B- Motor then runs at 82% for approximately 7-1/2

minutes. If demand has not been satisfied after 7-1/2 minutes,

C- Motor runs at 100% until demand is satisfied.

D- Once demand is met, motor runs at 50% for 30

seconds.

E- Motor ramps down to stop.

C D

100%

CFM

1/2 MIN 50% CFM

OFF

1/2 MIN 50% CFM

7 1/2 MIN 82% CFM

COOLING DEMAND

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”

toward drain lines?

● Will the unit be accessible for servicing?

● Has a secondary (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 properly?

● Is the filter clean, in place and adequately 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 5ºF 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 5ºF 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.

Maintenance

IMPORTANT

Do not operate system without a filter. A filter is required to protect the coil, blower, and internal parts from exces sive 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 is seen dripping from the secondary drain line,

contact a qualified service technician. This is a sign of a problem which must be investigated and corrected.

Cabinet Insulation

IMPORTANT

DAMAGED INSULATION MUST BE REPAIRED OR REPLACED before the unit is put back into operation. In sulation 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

Page 22

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.

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.

Use of Air Handler During Construction

Lennox does not recommend the use of its air handler unit during any phase of construction. Very low return air temperatures, harmful vapors and operation of the unit with clogged or misplaced filters will damage the unit.

Air handler units may be used for heating (heat pumps) or cooling of buildings under construction, if the following conditions are met:

● A room thermostat must control the air handler. The

use of fixed jumpers is not allowed.

● Air filter must be installed in the system and must be

maintained during construction.

● Air filter must be replaced upon construction

completion.

● The air handler evaporator coil, supply fan assembly

and duct system must be thoroughly cleaned following final construction clean-up.

● All air handler operating conditions must be verified

according to these installation instructions.

1. CUT INSULATION IN X PATTERN

2. APPLY GLUE

3. PRESS GLUED TABS AGAINST CABINET

Figure 24. Repairing Insulation

Page 23

MERIT® CBX25UHV SERIES

Installing Contractor’s Name_______________________ Installing Contractor’s Phone_______________________ Job Address____________________________________

Temperature

Duct

System

Duct Static

Installing Date_______________________________ Air Handler Model #___________________________

Thermostat

SUPPLY

AIR

Disconnect

Switch

Line Voltage

Integrated Control

Blower Motor Amps

Electric Heat Amps

RETURN

AIR

DUCT SYSTEM

SUPPL Y AIR DUCT Sealed Insulated (if necessary) Registers Open and Unobstructed RETURN AIR DUCT Sealed Filter Installed and Clean Registers Open and Unobstructed

INTEGRATED CONTROL Jumpers Configured Correctly (if applicable) Appropriate Links in Place (if applicable)

VOLT AGE CHECK Supply Voltage ___________ Low Voltage _____________ Electrial Connections Tight

DRAIN LINE Leak Free

Filter

TOTAL EXTERNAL STATIC (dry coil)

Supply External Static ______ ______ Return External Static ______ ______ Total External Static = ______ ______

ELECTRIC HEAT AMPS____________

INDOOR BLOWER AMPS___________ INDOOR BLOWER CFM____________

TEMPERATURE DROP (Cooling Mode)

Return Duct Temperature ___________ Supply Duct Temperature − ___________

TEMPERATURE RISE (Heating Mode) Return Duct Temperature __________ Supply Duct Temperature − __________

THERMOSTAT Adjusted and Programmed

Operation Explained to Owner

Drain Line

dry coil wet coil

Temperature Drop = ___________

Temperature Rise = __________

Explained Operation of System to Homeowner

Technician’s Name:_______________________Date Start−Up & Performance Check Completed__________

Figure 25. Start-Up and Performance Checklist (Up-flow Configuration)

Page 24

Installing Contractor’s Name_______________________ Installing Contractor’s Phone_______________________ Job Address____________________________________

Thermostat

Duct System

Integrated

Control

Filter

Installing Date_______________________________ Air Handler Model #___________________________

Disconnect

Switch

Line Voltage

Duct System

RETURN

AIR

Drain Line

DUCT SYSTEM

SUPPL Y AIR DUCT Sealed Insulated (if necessary) Registers Open and Unobstructed RETURN AIR DUCT Sealed Filter Installed and Clean Registers Open and Unobstructed

INTEGRATED CONTROL Jumpers Configured Correctly (if applicable) Appropriate Links in Place (if applicable)

VOLT AGE CHECK Supply Voltage ___________ Low Voltage _____________ Electrial Connections Tight

DRAIN LINE Leak Free

Duct Static

Temperature

SUPPLY

Electric Heat Amps

Blower motor Amps

TOTAL EXTERNAL STATIC (dry coil)

dry coil wet coil

Supply External Static ______ ______ Return External Static ______ ______ Total External Static = ______ ______

ELECTRIC HEAT AMPS____________

INDOOR BLOWER AMPS___________ INDOOR BLOWER CFM____________

TEMPERATURE DROP (Cooling Mode)

Return Duct Temperature ___________ Supply Duct Temperature − ___________

Temperature Drop = ___________

TEMPERATURE RISE (Heating Mode) Return Duct Temperature __________ Supply Duct Temperature − __________

Temperature Rise = __________

THERMOSTAT Adjusted and Programmed

Operation Explained to Owner

AIR

Explained Operation of System to Homeowner

Technician’s Name:_______________________Date Start−Up & Performance Check Completed__________

Figure 26. Start-Up and Performance Checklist (Horizontal Configuration)

Page 25

MERIT® CBX25UHV SERIES

Lennox Merit CBX25UHV, CBX25UHV-018, CBX25UHV-036, CBX25UHV-048, CBX25UHV-024 Installation Instructions Manual

Specifications and Main Features

Frequently Asked Questions

User Manual