Lennox G43 Furnaces | FurnaceCompare®

Lennox G43 Furnace Overview

The Lennox G43 gas furnace has not been manufactured since 2004, although the unit does appear to still be sold by some vendors today. The G43 is part of the Lennox Merit Series, and can achieve an AFUE of 92.1 percent. The upflow design allows for installation in closets or basements. An integrated control board gives the homeowner or technician full control in operating the furnace. Lennox’s own Duralok Plus heat exchanger can be found on the G43, as well as a secondary heat exchanger that captures extra heat and creates high efficiency levels.

Furnace Filters for the Lennox G43

Air Flow Configuration Cabinet Width Filter Size(s)
All 17.5″ 16x25x1 (side)
16x25x1 (bottom)
All 21″ 16x25x1 (side)
20x25x1 (bottom)
All 24.5″ 16x25x1 (side)
24x25x1 (bottom)

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Consumer Reviews of Lennox G43


  • Very Satisfied
  • Somewhat Satisfied
  • Neutral
  • Somewhat Unsatisfied
  • Very Unsatisfied
  • #11 of 29 Lennox Furnace
  • 25% of customers recommended

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Lennox G43 Furnace Reviews

"Defects in Lennox evaporator coil causes leaks"

1.0 rating
Very Unsatisfied

Builder installed a new G43UF Series gas furnace & air conditioner in our custom built home. Although only 4 years old, the evaporator coil had to be replaced – obviously defective. I had to pay labor on the installation of the coil. I received no extended warranty on the new coil. I contacted Lennox customer service and filed a written claim for assistance on the cost of coil replacement. Since then, I have contacted Lennox numerous times, but they continue to put me off and just ignore me. Customer rep says they are reviewing but it’s been 8 months and no response from Lennox. I’m thinking they have always known that these coils are defective. Also, the blower motor & fan on the furnace are very loud. Both have had to be replaced, but are still loud. There were other repairs that were made on this unit while it was still under warranty. I would not buy a Lennox unit again.



2.0 rating
Somewhat Unsatisfied

Bought 2 identical units (my home and rental home) based on the Lennox name. Ha! So much for name recognition anymore! The most annoying thing about BOTH units…is the “super special efficiency motor thing”..whatever it is. It vibrates the entire furnace!!! Both units!! It sounds like a bulldozer has started up in my basement when it comes on. I’ve tried tightening the bolts on the motor, but it didn’t help any. I had to actually TAKE THE MOTOR OFF and place dampening rubber spacers under the screws…it helped a TINY bit..but still……having to tinker and rig up a NEW furnace is uncalled for. No more Lennox for me. A friend of mine’s furnace just went out. I told them NOT to buy Lennox due to my experience. See what sending your work to CHINA/MEXICO does to your company name?!


"Not reliable"

1.0 rating
Very Unsatisfied

Cheap Chinese and Mexican parts continue to fail. Have had to replace several parts on ac & furnace due to failure. Lennox use to be top of the line, but I will never buy another one.

Polk County, Iowa

"Lennox g43"

5.0 rating
Very Satisfied

I just bought a g43 merit. 8hr removal/installation and is very quiet. No problems and no reviews of this model. I am looking forward to saving some money with this unit (90-92% efficiency) but I am a little concerned about negative feed-back of other units. I found this sight after purchase. Replaced Ruud because of 2 cracks in heat exchanger (25 y/old). I will keep up with maintainance schedule and keep you posted.

Middleville, MI

Other G43 Reviews

A Lennox G43 furnace owner writes in to justanswer.com about a problem with a �bubbling� sound coming from the vent pipe when the furnace is running. The owner believes the drain is blocked and asks how to clean it. An expert on the site states the process is not difficult and refers the owner to a page in the service manual.

Another Lennox G43 owner asks justanswer.com about large amounts of water in the condensate trap outside the furnace. This occurs during heating season. An HVAC contractor answers that the water may be freezing outside in the drain, and this could be blocking water flow. The drain may need to be relocated inside, he suggests.

A post on hvac-talk.com reveals that the Lennox G43 was installed by builders several years ago in many new homes. An HVAC installer comments that it is a noisy model, so he chose the Lennox G61V, which is reportedly a quieter model.

Lennox G43 Model Numbers

The G43 is available in different models which vary in efficiency and capacity.

Model Number AFUE BTUs per Hour
G43UF-24B-045-* 92.1 44,000
G43UF-24B-045-** 92.1 44,000
G43UF-24B-070-* 90 66,000
G43UF-24B-070-** 90 66,000
G43UF-36B-070-* 92.1 66,000
G43UF-36B-070-** 92.1 66,000
G43UF-36C-090-* 92.1 88,000
G43UF-36C-090-** 92.1 88,000
G43UF-36C-090H-* 90 88,000
G43UF-36C-090H-** 90 88,000
G43UF-48C-090-* 92.1 88,000
G43UF-48C-090-** 92.1 88,000
G43UF-48C-110-* 92.1 110,000
G43UF-48C-110-** 92.1 110,000
G43UF-48C-110H-* 90 110,000
G43UF-48C-110H-** 90 110,000
G43UF-60C-110-* 92.1 110,000
G43UF-60C-110-** 92.1 110,000
G43UF-60D-135-* 92.1 132,000
G43UF-60D-135-** 92.1 132,000

G43 Warranty

Lennox offers a 20-year limited warranty on the heat exchanger, and a 3-year limited warranty on the ignition control. All remaining covered parts have a 1-year limited warranty.

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