Help - Wiring thermostat with "C" Wire

[Notch1988]

I've had my radiant tube heater on a line voltage thermostat since day one but I decided I'd like to go to a 24v thermostat. 1 - my post purge on the heater will start working and 2 - the new thermostat uses WIFI.

Below is the wiring diagram for my heater. My thermostat is a Lyric T5. I will be running 18/3 wire as I have none ran now and will rewire the 120v to bypass the line voltage thermostat so I have power at the plug in all the time.

Looking at the wiring diagram, I'm assuming the hot side (red to blue) will go to the "R" terminal in my Lyric. Then I will run from the blue to purple side of the heater to the "W" terminal in the Lyric. For the "C" terminal in the Lyric I run to the yellow to green or GND terminal in the heater?

 

[bobbyjean]

i think your wiring is good...post purge ...hmmm guess that would be timed by the fenwal board...if so it should work as you say

 

[LS6 Tommy]

Your Lyric can be used as a three wire stat, so your understanding of the diagram is correct. That company uses really odd color codes...

Tommy

 

[Notch1988]

Thanks for the confirmation. I wired it as I said and it works but my post purge doesn't work. The heater manufacturer has very little info in their manual so I may have to make a call.