The Lennox G8Q3 is a discontinued gas furnace with an efficiency of up to 80% AFUE. The G8Q3 was manufactured as far back as the mid-1960's and was discontinued in the 1990's.
Questions about this model?
"1963 and still working great!"
My Lennox g8q3-90e-9 furnace has worked for 50 years. The only problem is the heat exchanger is getting quite brittle. Does anyone have a compatible heat exchanger to replace? Quality – they don’t make them like they used to!
"Heat Exchanger Failures"
In 1989 I had upgraded to a G8Q3-120E furnace. This unit performed well for 15 years. During a regular pre-winter service check, our servicing dealer’s technician asked permission to cut open the side to inspect the heat exchanger. When he had access to the heat exchanger, he found 4 major cracks on the Duracurve heat exchanger, that required immediate shut down and furnace replacement. This really bothered me as to why the dealer only advised us years after the problem was known. It is disturbing to think of the potential results with carbon monoxide entering the living areas.
There are several comments on HVAC forums such as doityourself.com from homeowners with problems with the fan and wiring with their G8Q3 furnaces. Most seem to be simple wiring repairs. There are also posts about pilot lights that aren't coming on and corroded heat exchangers, most of which are because the unit is so old.
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