Millivolt install Thanks Wyze Happy New Year!

3 days 2 wiring diagram revisions and the Wyze Thermostat is up and running on my 1960ā€™s gas converted gravity furnace :slightly_smiling_face: no parts required.



What a cool term. Never heard it before.

How did you power the thermostat with no parts?

My furnace is converted from Coal to Gas it uses

Our Valves use a transformer to Power the Valve opening and closing. After following wires marking what I had, the solution seemed easy, Just add the ā€œCā€ wire, I simply took the extra wire and connected it to the opposite side as the power coming from transformer so I made a ā€œCā€ wire here is a piece of my diagram. (NOTE: The Red/White wire from my transformer is power so the other is Common make sure you follow those wires and find the power before choosing the ā€œCā€ wire.)

As soon as I added the ā€œCā€ wire and switched my RH to RC this is what I ended up with

I must confess I did have some 5 wire Theremostat wire so I replaced the old cracked wire with new, no change on my furnace except adding the ā€œCā€ wire connection. I hope this helps someone I do not do HVAC please make sure what your doing before you do it, I grew up making Radio Shack projects so this was fun for me. Stay safe out there America God bless.


p.s. for those kids who have never seen a Mercury Bulb my furnace uses one for Temperature limit here is some pics.