This seems to be a problem specifically with whole house furnaces. I don't quite get why but I'm guessing cheap companies. Our gas fireplace has no such problem

This seems to be a problem specifically with whole house furnaces. I don't quite get why but I'm guessing cheap companies. Our gas fireplace has no such problems. Piezo electric knob to start the pilot (like your Coleman camping stove but it actually works - ask me how I know) and the pilot generates the electricity needed to actually let the gas flow. If the pilot isn't able to generate the electricity to open the gas valve then no gas ever enters the burn chamber. Again ask me how I know - yes those things gunk up and then can't supply the current you need to open the valve. Easy fix tho. Zero electricity needed and the upstairs stays warm. Also no cold air sucked into the house. The whole system is closed off towards the house. Love this thing!