Thor Forums

[javelin]

One more comment. While your on/off switch is wired wrong I don't think that is causing your no start issue. Just follow the schematic on the left and make sure your wires are connected to the devices as noted correctly. Maybe a connector got reversed on the on off switch. Back to the no start issue though. Your furnace runs normally for about 24 hours each time to swap the control boards.....so to me both boards are probably OK (famous last words). The fact the furnace runs 24 hours after each swap seems to also indicate clear propane feeds; combustion chamber etc. So what else is there.....the spark unit/flame sensor perhaps is going flaky......works for a while (at night perhaps with regular furnace restarts?) and then does not sense the flame after it sits cold for a period. Flame sensor is much cheaper than a control board if that's any consolation. When you do get this working again you will have lots of spares.