Best method to connect millivolt fireplace to Ecobee?

[sofakng]

I'd like to connect an Ecobee thermostat to my millivolt (TH/TP/THTP) fireplace.

If I understand correctly, I need a 24VAC transformer and an isolation relay.

Does anybody have any recommendations or information? I'd like to mount everything in a single junction box in the basement crawl space under the fireplace if possible.

 

[gthomas785]

That's right. You can use any 24v switching relay. From the thermostat connect R and C to the 24v power supply, then connect W and C to the relay input coil. The relay output NO(normally open) would connect to the millivolt wires from the fireplace.