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-   -   Lennox G23 heater randomly turns on and won't turn off (

kgold 05-20-2012 03:55 AM

Lennox G23 heater randomly turns on and won't turn off
I have a Lennox G23 furnace from 1994. About a week ago, in the middle of the night, I had the entire system turned off manually at the thermostate, but woke up to the heater going full blast, flame and all. System was still "off" at the tstat. The only way I could get it to stop was to unplug the unit. I plugged it in about 12 hours later, and it was fine another 24 hours, until the heater came on again while the AC was running. I've replaced the thermostat, BCC board, and have a brand new filter, but just experienced the exact same problem again. Any ideas?

beenthere 05-20-2012 05:05 AM

Intermittent short short in he thermostat wires.

biggles 05-20-2012 06:03 AM

with it running with no call...remove the stat off the subbase....still runs? remove the W1/W2 wires off the subbase...? go down to the furnace and remove W1/W2 off circuit board..shuts off :thumbsup:the stat wires R to W are touching calling for heat:wink: between the stat and furnace

kgold 05-20-2012 09:23 AM

Lennox G23 heater randomly turns on and won't turn off
I have a Okfulemaster dual fuel control board mounted to the bottom of the BCC box. Could that be bad and causing the problem?

beenthere 05-20-2012 11:30 AM

Yes, that could be the cause of your troubles.

kgold 05-20-2012 04:41 PM

After checking the wires, I'm really leaning to the Okfuelmaster being the issue. When I disconnect the thermostat entirely from it, it is still calling for heat. Would 16J92 Fuel Master FM21 be the correct replacement part? If so, it looks like the wiring is labeled completely differently. Do you have a resource that can translate the old wiring labels to the new?

beenthere 05-20-2012 05:07 PM

No I don't.

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