Replacing old Comfortmaker thermostat

[Sfsailor]

My old thermostat is a Comfortmaker brand Q674L 1538 from what I can tell. I can not find a diagram to confirm what the X terminal is on this system. Almost ever part is identical to the Honeywell Q674L thermostats except the terminals are different. On the Honeywell the X terminal is the same as the nest W2/AUX.  I'm trying to determine if I can use this and what thermal on the nest to use. Any help is appreciated.

[Patrick_Caezza]

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

I would suggest wiring it like this.

White - W1 to W2

Black - C to C

Yellow - Y to Y1

Orange - O to O/B

Blue - X to * (set as emergency heat)

Red - R to Rc

Green - G to G

[Sfsailor]

Could you explain the W1 to W2 change? On the help line they had me keeping it in W1. With a quick Google search I understood the comments about the X terminal. Thank you for that.

[Ryan_G]

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,

Ryan