I say it shouldn't matter where you set it-- the thermostat sends a signal as a relay (12v on or off) and not a rheostat/potentiometer (variable resistance based on the setting) to the furnace. If you didn't care about temp settings you could run the furnace with an on/off switch.
Thanks, that makes sense, I had the board tested today and it was fine. Bought a ignitor, will put that in and see if that's the issue. I'm getting ready for hunting season and can't wait.