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Compatibility to Thermotron Thermostat

Community Member

See attached pic:

In compatibility checker it states I need support.   Not sure how to wire to nest.  Appreciate any help

I have starting clockwise on picture:  G, O, X2, B, W, U, R, T, Y.  

W and U have a soldered bridge. 


My understanding is X2 is for Emergency heat, and T is often used for outside sensor.  Neither are in the app for setting up nest.  Regardless without those configured for X2 and T the app doesn't like just G, O, B, W, R, T.  U




Platinum Product Expert
Platinum Product Expert

Your current thermostat is only compatible with the Nest 3rd Gen Learning Thermostat.

This is how I would wire it.


Blue - B to C

White - W to W2 (set as AUX heat)

Red - R to Rc

Brown - T not used

Yellow - Y to Y1

Green - G to G

Orange - O to OB

Black - X2 to * (set as Emergency heat)

To ensure that I see your reply, please tag me using @Patrick_Caezza

Hi Patrick, I have a dual fuel system, used your wiring instructions and everything worked except for gas furnace, so switched (*) to alt heat stage 2 and when testing gas furnace did turned on, not sure if emergency heat is going to work or not but I don’t think I need it, before when too cold stage too would kick in and heated pretty quickly. So I think this should do it. Thanks for your help, it helped a lot

Community Member

Hi, I have the exact same thermostat and same connections, did this worked for you?

Community Specialist
Community Specialist

Hey folks,


Thanks for visiting the Google Nest Community. 


Since this thread hasn't had activity in a while, we're going to close it to keep content fresh.

If you have additional questions, feel free to submit another post and provide as many details as possible so that others can lend a hand. 


Hope this helps!


Kind regards,