Maybe it's changed lately, but most of the medium sized gas heaters (thinking fireplace inserts, fake wood stoves, etc.) have a feedback loop where the pilot li

Maybe it's changed lately, but most of the medium sized gas heaters (thinking fireplace inserts, fake wood stoves, etc.) have a feedback loop where the pilot light heats a thermocouple that opens the pilot light valve, plus a thermopile for opening the main valve when the thermostat switch closes. The fan won't run, but you'll still get radiant heat without main electricity.