Most Gas furnaces still rely on a electric powered fan to operate a central forced air heating system. And many modern thermostats are power operated and digital (though some do have batteries mostly that's so they don't loose the time and programs.)im curious, does anyone here run on natural gas furnaces? it may be a west thing, but if the power is out usually the gas is still flowing. i also will be using a Honeywell HZ-519 for a secondary heat source thats digitally controlled so that the house doesnt have to be the same temp as the frog rooms.