Can I connect a thermostate directly to a 24 volt transformer plugged into a wall outlet rather than taking the power from the furnace (LP fireplace in this case)? My existing thermostat runs on battery power alone and I do not see a transformer in the fireplace unit. WOuld be much simpler for me to connect to a transformer plugged into a wall outlet

If you do not have a transformer at the fireplace you must have a 120 volt gas valve. Therefore all you would need to make a thermostat work is two wires going to the thermostat, but it would have to be a 120 volt thermostat unless you used a relay to turn on the gas valve.

It is possible that you have a milivolt system?

If this in not what you were wanting to know send me more information.

Thank you for taking the time to chat with me. SItuation is I have an LP fireplace that is currently controlled by a battery operated thermostat. I want to replace the thermostat with a Venstar thermostat (for RF control from phone). My existing thermostat has all 6 wires from the unit giong into to sources (R and W or WH I believe). Works like a charm - ignites the fires when needed and turns it off when not. Just no power to the wall thermostat. ANy thoughts would be appreciated and THANKS AGAIN. THe set up I purchased may not work.

I still don't understand if you have a transformer or not. If not what power turn the gas valve on. Also what in the new thermostat would have to have 24 volts of power to make it work. My thinking is that you should be able to make the thermostat switch from on to off and back with nothing connected to the thermostat.

It is hard to reason without knowing just what you have.

OK. Let me try.

Fireplaces are typically a millivolt system and thus two terminals.
This means that you need an isolated contact and a low EMF contact. Preferably one that's silver.

The Idec RM2S-UL-AC24V relay would work fine.

http://www.remelectronics.com/Search...cturerAbbr=IDC

R & C go to the secondary of the transformer. W and C go to the new relay. The NO (Normally Open) contacts go where the existing thermostat was.