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©2025 Lennox Industries Inc.
Dallas, Texas, USA
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
WARNING
Every working procedure that affects safety means shall
only be carried out by competent persons. This appliance
is not to be used by persons (including children) with
reduced physical, sensory or mental capabilities, or
lack of experience and knowledge, unless they have
been given supervision or instruction concerning use of
the appliance by a person responsible for their safety.
Children should be supervised to ensure they do not
play with the appliance.
CAUTION
Leak Detection System installed. Unit must be powered
except for service.
WARNING
Maximum Altitude of application is 3200m above sea
level.
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.
CAUTION
Servicing shall be performed only as recommended by
the manufacturer.
INSTALLATION
INSTRUCTIONS
Merit
Series
®
CBK45UHVT Air Handler Units - R454B
MULTI-POSITION AIR HANDLERS
508439-01
3/2025
Table of Contents
General Information .......................................................2
Wiring Diagrams ............................................................3
BDC3 Blower Control ....................................................5
Adjusting the Blower Speed ..........................................5
Requirements ..............................................................10
Unit Dimensions - Upflow ............................................ 11
Unit Dimensions - Horiz. ..............................................12
Installation Clearances ................................................13
Installation ...................................................................13
Sensor / Bracket Installation .........................................16
Condensate Drain.........................................................19
Duct System and Filters .............................................20
Brazing Refrigerant Lines ............................................21
Sealing the Unit ...........................................................24
Electrical Connections .................................................24
Check-out Procedures .................................................25
Maintenance ................................................................26
Repairing or Replacing Cabinet Insulation ..................26
Professional Maintenance ...........................................27
Sensor Maintenance ....................................................27
Modes of Operation ......................................................27
Start Up Test Procedure ...............................................29
Decommissioning ........................................................30
NOTE - This unit is a PARTIAL UNIT AIR CON DITIONER,
complying with PARTIAL UNIT requirements of this Stan-
dard, and must only be connected to other units that have
been confirmed as complying to corre sponding PARTIAL
UNIT requirements of this Standard, UL 60335-2-40/CSA
C22.2 No. 60335-2-40, or UL 1995/CSA C22.2 No 236.
Partial units shall only be connected to an appliance suit-
able for the same refrigerant.
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.
Ducts connected to an appliance shall not contain a
potential ignition source
Page 1
IMPORTANT
WARNING
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Related Manuals for Lennox Merit CBK45UHVT-018
Summary of Contents for Lennox Merit CBK45UHVT-018
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Page 1: Table Of Contents
INSTALLATION INSTRUCTIONS ©2025 Lennox Industries Inc. Merit Series ® Dallas, Texas, USA CBK45UHVT Air Handler Units – R454B MULTI-POSITION AIR HANDLERS 508439-01 3/2025 Table of Contents General Information ............2 Wiring Diagrams ............3 BDC3 Blower Control ............5 Adjusting the Blower Speed ..........5 Requirements ..............10... -
Page 2: General Information
WARNING WARNING • Do not use means to accelerate the defrosting pro- For duct connected appliances, false ceilings or cess or to clean, other than those recommended by drop ceilings may be used as a return air plenum if a the manufacturer. -
Page 3: Wiring Diagrams
Wiring Diagrams SYSTEM FIELD JUMPERS SINGLE STAGE AIR CONDITIONER NEED ALL WARNING TWO-STAGE AIR CONDITIONER REMOVE Y1 TO Y2 SINGLE STAGE HEAT PUMP REMOVE R TO O USE COPPER CONDUCTORS REMOVE Y1 TO Y2 AND R TWO-STAGE HEAT PUMP TO O ONLY TWO-STAGE ELECTRIC HEAT REMOVE W1 TO W2... - Page 4 WARNING USE COPPER CONDUCTORS ONLY FIGURE 2. Low Voltage Connections (Variable-Speed Motor) Page 4...
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Page 5: Bdc3 Blower Control
JUMPER SETTINGS BDC3 Blower Control IMPORTANT Before changing jumper setting, make sure the motor JP1 15 PIN has completely stopped. Any jumper setting change will PLUG (BOARD TO MOTOR) not take place while the motor is running. Table 2 lists the recommended factory blower speed tap selections for Merit CBK45UHVT series units. -
Page 6: Blower Data
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 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 3... - Page 7 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 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 5...
- Page 8 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 speed setting. Continuous blower speed is approximately 50% of COOL speed setting. Lennox Harmony III™ Zoning System applications - minimum blower speed is 450 cfm. TABLE 8...
- Page 9 TABLE 10. CBK45UHVT Thermostat and Two-Stage Outdoor Unit Operating Sequence Operating Sequence System Demand System Response Thermostat Demand Relative Humidity Handler System Step Status (COOL) Comments Condition pressor NO CALL FOR DEHUMIDIFICATION Normal Operation Acceptable 24 VAC - Y1 Compressor and indoor air handler follow thermostat demand Normal Operation Acceptable...
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Page 10: Requirements
Lennox air handler units (with or without optional elec- NOTES – tric heat), MUST conform with National Fire Protection As- sociation (NFPA) standards: “Standard for Installation of... -
Page 11: Unit Dimensions - Upflow
Unit Dimensions – Upflow 1 (25) DETAIL OF PIPING PLATE 4-3/4 3/4 (19) (121) SUCTION LINE SUPPLY AIR LIQUID OPENING CONDENSATE LINE 14-1/2 DRAINS (2) (368) 2-3/8 (Horizontal) (60) 1 (25) 1 (25) CONDENSATE DRAINS (2) 4-3/8 (Upflow and (111) 2-3/4 Downflow) VOLTAGE... -
Page 12: Unit Dimensions - Horiz
Unit Dimensions – Horiz. 1-1/8 (29) DETAIL OF PIPING PLATE CONDENSATE CONDENSATE DRAINS (2) DRAINS (2) (Upflow and 4-3/4 3-1/2 (Horizontal) Downflow) (121) (89) 20-3/8 (518) (559) OPENING 1-3/4 (44) (19) SUCTION 2-3/4 LINE LIQUID (70) LINE 2-3/8 4-3/8 (60) (111) LOW VOLTAGE INLETS LINE VOLTAGE INLETS... -
Page 13: Installation Clearances
• Work shall be undertaken under a controlled procedure WARNING so as to minimize the risk of a flammable gas or vapor being present while the work is being performed. To prevent serious injury or death: 1. Lock-out/tag-out before performing maintenance. •... -
Page 14: Refrigerant Metering Device
5. Refrigerating pipe or components are installed in a is a consideration, procedures such as safely remove re- position where they are unlikely to be exposed to any frigerant following local and national regulations, purging substance which may corrode refrigerant containing the circuit with inert gas, evacuating (optional for A2L), components, unless the components are constructed of purging with inert gas (optional for A2L), or opening the... -
Page 15: Horizontal Applications
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. -
Page 16: Downflow Application
11 - If suspending the unit, it must be supported along the TOP CAP ROTATED TO entire length of the cabinet. If using chain or strap, CORRECT POSITION use a piece of angle iron or sheet metal attached TOP CAP SCREWS CABINET SUPPORT to the unit (either above or below) so that the full... - Page 17 2 - Follow instructions for right-hand discharge as Horizontal Left Configuration outlined in previous section on page 14. 1 - Remove sensor bracket assembly from vertical position. Do not remove sensor from bracket, and 3 - With air handler unit panels removed, install sensor do not disconnect or reroute sensor wire from the bracket assembly to the unit by lining up holes in control panel area.
- Page 18 3 - With air handler access panels removed, install sensor bracket assembly to the side of the cabinet by lining up holes as shown in figure 13. FIGURE 13 (Detail) 4 - Loop and bundle any excess sensor wire with a wire tie.
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Page 19: Condensate Drain
METERS) 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 MA IN DRAIN. -
Page 20: Duct System And Filters
Lennox Product drainage without a proper trap. Specifications bulletin. Additional information is provided 7 - Route the drain line to the outside or to an in Service and Application Note ACC002 (August 2000).. -
Page 21: Brazing Refrigerant Lines
Handle the refrigerant lines gently during the installation Technical Support Product Applications for assistance. process. Sharp bends or kinks in the lines will cause a To obtain the correct information from Lennox, be sure to restriction. communicate the following information: Model and capac- Do not remove the caps from the lines or system ity. - Page 22 2 - Make sure that the suction line is insulated over the If refrigerant sensor is required, it shall be mounted as follows: entire exposed length and that neither suction nor liquid lines are in direct contact with floors, walls, Upflow Applications: Mounted on an unused side furnace duct system, floor joists, or other piping.
- Page 23 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.
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Page 24: Sealing The Unit
WARNING Sealing the Unit Seal the unit so that warm air is not allowed into the cabi- Electric Shock Hazard. net. Warm air introduces moisture, which results in water Can cause injury or death. blow-off problems. This is especially important when the Foil-faced insulation conductive... -
Page 25: Check-Out Procedures
4 - Use UL-listed wire nuts to connect the field supply 208 VOLT CONVERSION conductors to the unit black and yellow leads, and 1 - Disconnect all power supplies. the ground wire to ground terminal marked GND. 2 - Remove the air handler access panel. 5 - 5. -
Page 26: Maintenance
• Is the indoor coil factory-installed TXV properly sized for • If water should start coming from the secondary drain the outdoor unit being used? line, a problem exists which should be investigated and • Have all unused parts and packaging been disposed corrected. -
Page 27: Professional Maintenance
• When cleaning the evaporator coil, remove sensor from the coil. Follow recommended coil cleaning guidelines Lennox does not recommend the use of its air handler unit as described in installation instructions. during any phase of construction. Very low return air tem-... -
Page 28: Diagnostic Codes
Fault Table 14 lists the functions of the Test button during each mode of operation. When a fault is detected within the RDS Non-Communi- cating Blower Control Board, the indoor unit blower en- TABLE 14. Test Button Function gages and remains engaged at a constant output until the fault is cleared. -
Page 29: Additional Applications
• Heating could be lost during a cold night The RDS Non-Communicating Blower Control Board trig- gers the external alarm system when it enters Leak De- • Cooling could be lost during a hot day tected mode. For alarm notifications, the RDS Non-Com- •... -
Page 30: Decommissioning
Diagnostic Codes and Troubleshooting TABLE 16. LED Diagnostic Codes State LED Diagnostic Code Action Required Initializing Flashing green None Solid green. Monitoring If a prior mitigation occurred, a blue flash None interrupts the solid green LED. Mitigating Check coil tubes for leak. Repair the issue and restart the equip- Flashing blue (Leak Detected) ment. -
Page 31: Integrated Control
Installing Contractor’s Name_______________________ Installing Date_______________________________ Installing Contractor’s Phone_______________________ Air Handler Model #___________________________ Job Address____________________________________ Thermostat Line Voltage SUPPLY Disconnect Switch Integrated Control Temperature Duct Blower Motor Amps System Electric Heat Amps Duct Static RETURN Filter Drain Line DUCT SYSTEM TOTAL EXTERNAL STATIC (dry coil) dry coil wet coil SUPPLY AIR DUCT... - Page 32 Installing Contractor’s Name_______________________ Installing Date_______________________________ Installing Contractor’s Phone_______________________ Air Handler Model #___________________________ Job Address____________________________________ Line Voltage Disconnect Switch Thermostat Integrated Control Duct System Duct System Filter RETURN SUPPLY Electric Heat Amps Blower motor Amps Drain Line Duct Static Temperature DUCT SYSTEM TOTAL EXTERNAL STATIC (dry coil) dry coil wet coil...
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