My home was built in 1957, I had a new heat pump system put in (which I now hate) 7 years ago. It works fine in the summer, but in winter it doesn't heat the house very well.
At the time, I kept the old Coleman, through the wall natural gas heater as emergency heat, as works without power to the house. It's old and inefficient, but it's done it's job for 50+ years. This year I replaced the old thermostat,with a new Honeywell round heat only mode. I haven't been able to get it fired up once this winter though. I've contacted a couple of local heat/air places, and noone has ever heard of this heater and don't know how to service it apparently.
So I'm trying to troubleshoot it myself and see if the problem is the thermostat, or the unit itself. Am I correct in thinking that if I manually touch the two wires together (red/white), sans thermostat, the unit should come on if it's going to?
Best Answer
I assume you are dealing with a gravity wall furnace, now made by Williams and Empire, and commonly found in California. They require no AC power. They use a thermocouple on the pilot light to power (via the thermostat) a millivolt gas solenoid. They sell special thermostats for this application. A "common" thermostat may or may not work, depending on its ability to switch a very low voltage at comparatively high current, and function without 24v power.
Electronic thermostats cannot work, unless you supply 24v to them and supply a relay to switch the millivolt line... but that makes the furnace dependent on AC power, which defeats the purpose of this type of furnace!
Yes, touch red and white together, and the unit should come on.
If it does not, first check that the pilot is on (no pilot, no millivolts). Then check the 2 wires with a voltmeter, there should be some fraction of a volt of electricity. If not, the pilot is out or you have a thermocouple problem.
Parts are readily available for Empire and Williams furnaces, and worse comes to worst, you can replace one in-kind, though you'll have to special order it in the northeast or midwest. For some reason, people in those areas have a revulsion to furnaces that work without electricity.