I have a Heatilator gas fireplace wired to a thermostat. It used to work just fine. Now, if I turn up the 'stat, nothing happens. If I short out across the 'stat contacts, the fireplace comes on and stays on until the 'stat is satisfied. This process repeats itself next time the 'stat calls for heat.

I tried replacing the 'stat - same results. I tried a new (temporary) wire between the fireplace and 'stat (about 6'), same results.

Any ideas? Heatilator hotline was no help.

You need a simple old style thermostat to start with. The will not work well on the newer battery digital ones.

If you short across the thermostat contacts at the thermostat and the unit runs it means there is too much resistance in the thermostat you are using and the voltage will not pass through.

Try a "Millivolt" thermostat. You will be limited to a wire distance of 25' from thermostat to fireplace using 18ga. Wire.

Thanks! The millivolt stat works just fine.