I have a Lennox 80MGF2-60A-5 gas furnace. It was installed in October of 1996. It looks like it has an EGC-2 circuit board. (No red diagnostic button on the circuit board which I see is the egc-1 model) Sometimes I hear it try to start and it won't. The combustion air blower always starts and runs for the pre-purge, and I then hear the ignition spark light, then the unit stops when it does not light. Other times, everything works...the ignition sparks, and the four burners do light up and it heats fine. Once, it ignited and I saw the four burners burning for about .5 seconds and then it turned off. The last two mornings I have found that the unit will not start. I believe it locks itself out after a certain number of attempts. When I come home at night, if I trip the power to the unit, it will start up usually, or take 2 or 3 power resets before it will start. Any ideas on why it sometimes does light and sometimes not? And what part might be the culprit?

I have a 750mV Honeywell gas wall furnace. It got moved from one wall to another. Every since the move and reconnect, the heater has stopped working. The only thing that changed from the original install is that I got a new Honeywell thermostat. It is the RTH 111. It says it's compatible with the mV system. So, when I first tried to light the pilot, everything went just fine but after the flames came on, the heater would click and everything would go out. I did some research and then when trying to re-light the pilot, realized that it wouldn't stay lit. My research then said to replace the thermopile. I took it out (it looked toasted) and went out and replaced it with a new one. The new one lights the pilot just fine and it stays lit. Again, I went through the process of trying to get the heater to work. I turned on the thermostat to the highest setting, lit the pilot, turned the gas on and it worked for about 30-45 seconds. The flames come on beautifully and the heat starts (there's no blower) and then it clicks and shuts off pilot and all. I have seen that there is a possibility that my thermopile is overheating. So, then I went to the pilot adjust screw and turned it clockwise to see if I could get the pilot flame down just a little. I turned it clockwise quite a bit and I still can't get the heater to stay on. Should I keep turning some more until it works or is there a possibility that something else might be wrong? I don't see a flame sensor that needs to be cleaned. The only parts to this heater are the gas valve unit, the pilot and the thermopile. Is there a possibility that I have the thermopile wired wrong? As of now, the there are only three terminals on the gas valve. Upper right, lower right and lower left. The pilot is pre-connected. I have the thermostat white wire on the bottom left and the red (I believe it's the hot) wire on top right. I have the thermopile's red (hot wire) to the top right and ground to the bottom right. Can anyone please help? I'm in northern CA and it's getting pretty cold at night. Space heaters don't do much except waste electricity. A huge thanks in advance!