Compatibility Check

[myivhor]

We just bought a new place that has an old school Trane Weathertron thermostat. Our HVAC system is a fully electric central AC with electric heating.

I've been holding on to a Nest Thermostat 2020 that I just tried to install but was told by the app that it was incompatible, but I've heard mixed reviews that the compatibility checker is not reliable so I figured I'd ask here.

The current thermostat has wires connected to R, W, Y, G, O, B, and X2.

Hoping for some insight, and if this isn't compatible, if someone can tell me if any Nest thermostat would be compatible.

Thanks!

[EduardoN · Accepted solution]

Hi @myivhor,

Thanks for contacting this community! Congratulations on your new home! I understand that your new house had a classic Trane Weathertron thermostat, but you've installed a Nest Thermostat (2020) that you had saved. However, for some reason, you're getting a message saying it's not compatible with your system. Don't worry about the comments; I'm here to help you!

Regarding the compatibility issue, I would like to ask you some questions about your system in order to give you the most specific information possible.

• Please let me know what kind of HVAC system you have. Is it a conventional system with a furnace and air conditioner, or is it a heat pump system?
• What is the color of each wire, and what is the corresponding letter on the thermostat terminal that it's connected to? Please list them out (e.g., Red to R, White to W, Yellow to Y, Green to G), if you can please send a photo.
• Is your system low-voltage (24V AC) or high-voltage (line voltage)?
• Is there a separate wire for emergency or auxiliary heat? If so, what terminal is it on?

Visit our Help Center to learn more about Nest thermostat compatibility.

Please feel free to share any additional details you think might be relevant.

Best regards,
Eduardo

[myivhor]

This is my thermostat. The Nest thermostat is not yet installed. The HVAC system is an electric central AC with electric furnace for central heating. From what I understand, it is a low voltage system. There is no emergency heating in the home.

[EduardoN]

Hi @myivhor,

Thanks for the update about the wiring! Regarding the information I can verify about the wires in a much more appropriate way, I'd like to let you know there are two thermostats compatible with your wiring system: the Nest Learning Thermostat (3rd and 4th gen). The compatibility is as follows:

• The O wire (orange) connects to O/B.

• The G wire (green) connects to G.

• The Y wire (yellow) connects to Y.

• The R wire (red) connects to RH or RC.

• The W wire (white) connects to W1.

• The B wire (blue) connects to C.

Keep me posted.

Best regards,
Eduardo

[myivhor]

Thank you for the insight. Is there any reason the Nest 2020 or the Thermostat E will not be compatible? Just curious.

There is an R connector instead of RH/RC, and a W connector instead of W1 on those model.

Thanks!

[EduardoN]

Hi @myivhor,

That's a great question! At this point, the difference would be the system compatibility with the Nest Thermostat (2020 and E). In the original photo you sent me, you have the X2 wire. If you want to use that wire, you would need to use the Nest Learning Thermostat (3rd and 4th gen) because the X2 wire would connect to the "**" terminal. With more terminals, it is compatible with more complex systems.

However, if you don't want to use the X2 wire, the Nest Thermostat 2020 and Nest Thermostat E would be compatible, but you wouldn't have all the features. I apologize for not specifying where the X2 wire should be connected.

Keep me posted.

Best regards,
Eduardo