I have a (fairly standard) natural gas water heater that is only hooked up to a water supply line and gas - no electric. I'm wondering how the thermostat is able to open/close the gas valve without electric?
Based on some Googling, I've found that the thermostat itself is a thermistor, which provides variable resistance based on temperature. That implies some electric current coming from somewhere. But where? And what provides the actual energy to open/close the gas valve?
Haven't been able to find this anywhere...