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©2018 Lennox Industries Inc. 

Dallas, Texas, USA

Page 1

THIS MANUAL MUST BE LEFT WITH THE 

HOMEOWNER FOR FUTURE REFERENCE

 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, or the gas supplier.

 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.

INSTALLATION 

INSTRUCTIONS

MULTI-POSITION AIR HANDLERS

507836-01

3/2018

Merit

®

 Series  

CBX25UH-T Air Handler Units 

50 Hz

Shipping and Packing List 

Package 1 of 1 contains: 

1 –  Assembled air handler unit factory-equipped for upflow 

or horizontal air discharge application (includes upflow 

and horizontal drain pans and 

preinstalled air filter

).

Check the air handler for shipping damage; if found, im-

mediately contact the last carrier. Check the unit rating 

plate to confirm that delivered unit matches order. 

General Information 

The CBX25UH air handler is designed for indoor instal-

lation only. As shipped, the unit is ready for installation 

in either upflow, horizontal left-hand or right-hand air dis

-

charge applications. Air filters and other accessories are 

available and listed in the CBX25UH Product Specification 

bulletin (EHB) for ordering.
All units are shipped with a factory-installed check/expan-

sion valve. 
This instruction is intended as a general guide and does 

not supersede local or national codes in any way. Consult 

authorities having jurisdiction before installation. 

 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.

IMPORTANT INFORMATION FOR INSTALLER

This unit has a delay relay that delays the supply blower “ON” for 1 second and keeps the blower “ON” for 45

seconds on all fan and cooling demands. 

1

SECOND

DELAY

OFF

100%

L/s

100%

L/s

45

SECS

COOLING

DEMAND

1

2

3

4

Summary of Contents for CBX25UH-024

Page 1: ...Check the air handler for shipping damage if found im mediately contact the last carrier Check the unit rating plate to confirm that delivered unit matches order General Information The CBX25UH air ha...

Page 2: ...Page 2 CBX25UH Unit Dimensions Upflow Inches mm...

Page 3: ...e 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 appl...

Page 4: ...n HORIZONTAL DRAIN PAN MUST BE REMOVED UP FLOW DOWN FLOW DRAIN PAN FIGURE 1 Upflow Configuration HORIZONTAL APPLICATIONS IMPORTANT When removing the coil there is a possibility of danger of equipment...

Page 5: ...ssembly bottom drain pan and horizontal drain pan as one unit from the air handler FIGURE 5 Remove Coil Assembly Bottom Drain Pan and Horizontal Drain Pan as a Unit 4 Remove the blow off prevention br...

Page 6: ...ck into the air handler 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...

Page 7: ...LOCATED ABOVE A FINISHED SPACE THE SECONDARY DRAIN PAN MUST HAVE A LARGER FOOTPRINT THAN THE AIR HANDLER MAIN DRAIN TO APPROVED DRAIN FOR NEGATIVE PRESSURE COILS BLOWER AFTER COIL TRAPS ARE REQUIRED...

Page 8: ...n is provided in Service and Application Note ACC002 August 2000 INSTALL CONDENSATE DRAIN The air handler is provided with 3 4 NPT condensate drain connections IMPORTANT On some pans the primary and s...

Page 9: ...completed 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 li...

Page 10: ...azing 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 a...

Page 11: ...LLOW FILTER ACCESSIBILITY NOTE CBX25UH 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 REF...

Page 12: ...te electric power supplies before opening access panel Unit may have multiple power supplies WARNING Electric Shock Hazard Can cause injury or death Foil faced insulation has conductive characteristic...

Page 13: ...ND 5 5 Replace the air handler access panel SIDE TOP FIGURE 15 Electrical Connections Upflow Configuration NOTE To avoid the possibility of moisture damage to the control in some right hand discharge...

Page 14: ...U BLK BLK GRN BLUE BLUE BLU BLK GND 1032 1030 1031 1060 NOTES 1 FACTORY SPEED SET TO MEDIUM BLUE FOR 024 030 036 048 AND 060 2 ALL WIRES NOT LABELED ARE PART OF ITEM 1010 240 FIGURE 17 Typical Wiring...

Page 15: ...r filter in place All factory settings are medium speed All data given while air handler is operating with a dry DX coil All downflow applications run on high speed when utilizing electric heat NOTE R...

Page 16: ...eeds High Medium Low Pa in w g L s cfm L s cfm L s cfm 25 0 10 675 1430 597 1265 517 1095 50 0 20 632 1340 562 1190 486 1030 75 0 30 585 1240 521 1105 451 955 100 0 40 533 1130 472 1000 394 835 125 0...

Page 17: ...seconds 4 Motor ramps down to stop 1 SECOND DELAY OFF 100 L s 100 L s 45 SECS COOLING DEMAND 1 2 3 4 FIGURE 20 Blower Time Delay COOLING COOLING ONLY OR HEAT PUMP When the thermostat calls for coolin...

Page 18: ...e cabinet which leads to sheet metal corrosion and subsequently component failure REPAIRING DAMAGED INSULATION Areas of condensation on the cabinet surface are an indi cation that the insulation is in...

Page 19: ...Duct Temperature ___________ THERMOSTAT Adjusted and Programmed Return External Static ______ ______ Total External Static ______ ______ 6 Supply Duct Temperature ___________ Temperature Drop _______...

Page 20: ...ternal Static ______ ______ 6 6 Supply Duct Temperature ___________ Temperature Drop ___________ TEMPERATURE RISE Heating Mode Return Duct Temperature __________ Supply Duct Temperature __________ Tem...

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