Old Lennox Furnace - Model GH6 100T (maybe thermostat maybe furnace problem)

In the last several days my thermostat and furnance don't seem to be ""talking"" to each other properly.

It seems that when I leave my thermostat alone it activates the furnance to go on when called upon. If I want to do a manual override on the thermostat it doesnt activate the furnace at all.

The contact points on the control (in furnace) do seem greasy but is that enough to have my heating system behave in this way?

Jack

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jack
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jack posted for all of us...

Asked and answered MANY times - do your own research.

Reply to
Tekkie®

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jack

duradrinx had written this in response to

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: I really hate to bump up a very old post. But I am having this exact issue.

I had replaced my old mercury thermostat and shortly after this started happening to me. I had the furnace looked at 3 times, 2 differant companies. All three techs told me it has to be the thermostat. Well after trying 2 more thermostats, differant manufacturers. Nothing has changed.

Did anyone find a solution to this?

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Reply to
duradrinx

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:

I suggest you put back the old thermostat.

But one "clue" might be found by asking yourself how the thermostat gets the power (I ASSume it is one of those electronic gadgets with a display.)

The old mercury thermostats are near idiot proof. They can even work on "milivolt" system where the power to turn on the gas valve comes from a thermopyle soaking in the pilot flame. If it just calls for heat it only needs 2 wires. If it allow you to turn the fan on it only requires 3 wires. If there is an A/C with the furnace it only requires 1 more wire.

Reply to
John Gilmer

itten this in response to

Forget about power or the furnace or anything else. If the furnace always comes on as it should when the thermostat is left in the run program mode and only fails to come on when you override it, then it's either a bad thermostat or operator error. Also, the thermostat and the furnace don't "talk to each other". The thermostat is just a couple of switches that close to activate the furnace or just blower seperately, etc. So, if that switch is closing in the "run program mode", but not when you override it, it's only the two above possibilities.

Reply to
trader4

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