Lennox CBK45UHET-042-230-71 21.5" Width 42,000 BTU Air Handler

The Lennox CBK45UHET-042-230-71 is a 3.5 ton Merit Series air handler for R-454B systems, with a constant torque (ECM) blower and an R-454B check/expansion valve installed at the factory. It comes in a 21.5-inch wide cabinet that ships ready for upflow or horizontal installs.

Key specs

• Capacity: 3.5 tons (42,000 BTU)
• Blower: 3/4 hp constant torque motor, 568 to 1,656 cfm
• Connections: 3/8-inch liquid and 7/8-inch suction, sweat, plus two 3/4-inch FPT drains
• Filter: 18 x 20 x 1 inch
• Shipping weight: 169 lb
• Coil: Lennox Quantum coil with aluminum tubing and ripple-edged aluminum fins

Reading the model number

CB is an air handler, K is R-454B, and 45 is the Quantum coil series. UH is upflow/horizontal, E is the high-efficiency constant torque motor, and T is the factory check/expansion valve. 042 is 3.5 tons, 230 is 208/230V single-phase, and 71 means an R-454B valve is installed.

What it pairs with

The AHRI Directory lists it with these Lennox units we sell: EL15KC1, EL16KC1, EL18KCV, EL22KCV, ML13KC1, ML14KC1, and ML17KC2 air conditioners and EL16KP1, EL18KSLV, EL19KPV, EL21KLV, and ML14KP1 heat pumps. Listed ratings run from 13.8 to 19.75 SEER2, and the best match is the EL22KCV-036-230 air conditioner.

For electric heat, Lennox lists ECB45 heaters from 4 to 15 kW for this size: 4, 5, 7.5, and 10 kW with a terminal block or a circuit breaker; 12.5 and 15 kW with a circuit breaker.

Sizing and fit

Downflow needs Lennox's Y9659 downflow kit, and horizontal left-hand discharge needs the horizontal drain pan moved. Match the air handler to your outdoor unit's tonnage.

Warranty and registration

HVAC USA is an authorized Lennox reseller, and everything we sell is new factory equipment. Your full Lennox warranty applies when a licensed, manufacturer-certified contractor installs your system and registers it within 60 days.

Shipping and help

This item ships free from our Kansas City warehouse to the lower 48 states and D.C., and so does the rest of your order, except to Washington, Oregon, and Idaho, where you pay the shipping rate shown at checkout. For Alaska, Hawaii, Puerto Rico, other U.S. territories, or an APO or FPO address, call or text us for a quote. Call (913) 364-0070, Monday to Friday, 9am to 5pm CST, and we'll help you confirm sizing and an AHRI-matched pairing before you order.