Lennox ML180UH045V36A 80% AFUE 44,000 BTU 14.5" Variable-Speed Gas Furnace

The Lennox ML180UH045V36A is a Merit Series single-stage gas furnace rated 44,000 BTU input and 36,000 BTU output at 80% AFUE. It comes in a 14.5-inch A cabinet, installs upflow or horizontal, and has a variable speed blower sized for 1.5 to 3 tons of add-on cooling.

Key specs

• Heating: 44,000 BTU input, 36,000 BTU output, 80% AFUE, single-stage
• Cabinet: A size, 14.5 inches wide, upflow or horizontal (left or right)
• Blower: 1/2 hp variable speed motor, 380 to 1,320 cfm, for 1.5 to 3 tons of cooling
• Temperature rise: 15 to 45°F

Reading the model number

ML is Lennox's Merit line, 1 means single-stage, 80 is the AFUE, and UH is upflow/horizontal. 045 is the 44,000 BTU input, V is the variable speed blower motor, 36 is the nominal add-on cooling size, and A is the 14.5-inch cabinet.

What it pairs with

Coils with the same letter physically match the furnace, so you want a Lennox coil with A in its size code, such as a CK40CT, CK40HT, or CK40UT.

The AHRI Directory lists this furnace in certified systems with CK40CT, CK40HT, and CK40UT coils and Lennox EL15KC1, EL16KC1, EL18KCV, EL22KCV, ML13KC1, ML14KC1, and ML17KC2 air conditioners, plus EL16KP1, EL18KSLV, EL19KPV, EL21KLV, and ML14KP1 heat pumps. Your efficiency rating depends on the exact outdoor unit, coil, and furnace together.

Sizing and fit

Size the furnace from a Manual J load calculation. Filters and filter mounting aren't included, so plan for a filter rack.

This model doesn't carry the X low NOx code, and Lennox says this furnace series can't go in the South Coast, San Joaquin Valley, and Bay Area air districts. It isn't certified for mobile homes, RVs, or outdoor installs.

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.

Compare related Lennox furnaces

Compare this furnace with other Lennox 80% AFUE furnaces, Lennox Merit furnaces, Lennox single-stage furnaces and Lennox 44,000 BTU furnaces. You can also browse all Lennox gas furnaces. Adding cooling? Pick a matching Lennox evaporator coil for the cabinet width.

Shipping and help

It ships from our Kansas City warehouse to the lower 48 states and D.C. It ships free when your cart also has an item that ships free, except to Washington, Oregon, and Idaho. 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.