Lennox gas furnace


Old 11-17-00, 06:54 PM
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I am renting a home with a Lennox gas furnace. This is my first experience with a gas fired furnace and I notice that it runs in 10 minute cycles. When I turn the thermostat up and call for heat 1)a blower comes on bringing air in from the outside, 2)one minuted later the furnace lights,3)soon the fan blows for about 9 minutes and shuts down. The room temp. has not gone up enough so it starts over. Sometimes 3-4 times until thermostat is satified? This seems odd to me. Any Ideas? Thanks ,Larry
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Old 11-17-00, 07:29 PM
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Sounds like a furnace with an extremely dirty air filter. Try checking it and replacing it, if needed.

It could also be a module, pilot prover, gas valve solenoid or the forced draft fan system. These items will require a heating agency to diagnose and correct.

In case your wondering <since this is your first expierence with a gas fired furnace> the condition you currently have with the furnace isn't how a properly operating gas fired forced air furnace is suppose to work.

Good Luck,
Old 11-18-00, 03:25 AM
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Hi Tom,
Thanks for the fast reply. I did change the filter on the very first day we were here... very dirty. So I will have the system checked out. My only thought was that it may be some new energy saving system that runs weird. Thanks for your help. Larry
Old 11-18-00, 06:11 AM
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Also check the thermostat, it controls cycle times.
Best way to set the thermostat is get a digital on, it doesn,t have a heat anticipator.
If it is not digital there is an adjustment at the thermostat called a heat anticipator. It is set to the amprage the furnace and wiring are using to operate the heating cycle.To properly adjust remove thermostat, test amperage across R to W.
Watch the meter for a couple of minutes as the heat comes on. Sdet the heat anticipator to the amperage the meter read.
If you don't have a meter, you could increse the cycle to be longer and see if the thermostat stays on. Youn can see the mercury shift to the other side as it shuts the furnace off.
If your having the furnace serviced have them check the heat anticipator.

Good Luck
Mr Foster

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