I have a propane wall furnance that is'nt firing, the thermostat is not appearing to trigger the unit. The pilot is fine and the thermostat is a simple unpowered one with mercury that appears to be in working order according to my multimeter.
What may be wrong with the unit? How does one go about further diagnosing the issue? I did have to do some work on the thermopile some time back, is it possible the thermopile may be generating enough voltage to keep the pilot but prevent ignition?