I am in the process of replacing a millivolt thermostat that controls my Regency Fireplace insert. Coming off the insert are two wires that when connected together open the gas valve and the fireplace insert begins operation.

I purchased a new thermostat that allows me to call the thermostat via telephone to adjust the temperature of the room. Unfortunately, this is a 24v thermostat. When I called the vendor, they suggested I get a 24v transformer and a relay.

I suspect that I need to connect the two wires from the insert to the NO and C terminals on the output of the relay. What should my input side look like?

I think... one wire from the 24v transformer will go to the R connection of the t-stat, the other wire will go to common on the relay, which somehow goes to common on the t-stat. The W wire will go to the relay so when the t-stat engages, power will flow through W to the relay, causing the magnet to close NO and thus igniting the fire place.

Does this sound right? What am I missng? What type of relay do I need?

Thanks,

Roland

Any old relay with a 24 volt AC coil will work. Red wire from the transformer to the R terminal of the thermostat, white wire to one coil terminal on the relay, and the blue wire from the transformer to the other coil terminal. Some thermostats will need the blue wire connected to the thermostat too.

If the thermostat is powered by a battery and just switches R to W, you may be able to skip the relay and transformer. If it will power up without being connected to a 24 volt source, check for 0 ohms between R and W when it calls for heat.