My sister has an ancient Biltwel Gravity Furnace in her basement that just stopped working. For four years she has just jumpered the thermostat wires upstairs to run the furnace. (Thermostat face completely gone.) There are only two wires coming into the thermostat and NO 110 VAC.

In the basement, I can find NO 110VAC going into the unit. As a gravity unit, there is no blower. When I jumper the two thermostat wires at the gas valve, the unit still doesn't work.

What am I missing? What opens the gas valve if there is no 110VAC anywhere? What is my next step to get it working? The gas valve also has a pair of wires that goes up into the lit pilot light assembly.

Thanks!

What you have is a pilot generator, this produces a small amount of electrical currant which operates the gas valve through the thermostat, if the pilot is lit and has a good blue flame it is most likely you have a bad generator, (make sure gas valve is turned on )this is the part that is in the flame with the two wires coming from it. To remove this all you have to do is either unscrew a nut at the bottom of it or simply pull it down out of the pilot. Good luck, Mike

When I jumper the two thermostat wires at the gas valve it goes on when I take it off it goes off