Is my old thermostat compatible w/ NEST? Wires read: W2 E D/B R L G C Y

[rgaila]

Disclaimer: This thread was migrated from our previous version of the Google Nest Community. You can continue to receive updates on your thread issue here or simply ask, browse or more in the new Google Nest Community.

Original Poster: RAII 

Trying to see if my old thermostat is compatible with a NEST thermostat. The wires read as follows from left to right, top to bottom: 

W2. E. D/B. R. 

  L.   G.  C.  Y.  

Any help is appreciated, thanks! 

[rgaila]

Hi Raii, 

Thanks for reaching out to us and welcome to our community! That's great that you're considering a Nest thermostat for your home. I'm happy to help decode your wiring setup. 

While I can see your W2, E, R, L, G, C, and Y wires (secondary heat, emergency heat, heat/cool, lights, fan, c-wire, and cooling, respectively), I am unsure of the D/B wire--usually, A/B/C/D wires can indicate a proprietary system that unfortunately is incompatible with Nest thermostats. 

I would suggest using the Compatibility Checker to double-check in this case. If it's still unclear, a local pro would be advisable to confirm what kind of system you have. If you also still have the HVAC manual, you can send that over and we can look more into it, too. 

Hope this helps! Let me know if you have any questions for us. 🙂 

-From Ai, Community Specialist.

[jacksonland]

I have a similar thermostat to the previous post and am wondering if mine is compatible with Nest. No wires seem to have labels.

Not sure how to add a photo

Emerson 1F78 thermostat

[aatienza]

Hey jacksonland,

Thanks for reaching out. Could you share a photo of how your previous thermostat is wired? What country are you located in? Additionally, you could also check on our Compatibility Checker or this link to know more about your system's compatibility with our Nest thermostats: https://goo.gle/375XG2f

Thanks,

Archie

[jacksonland]

I am in the U.S. I tried to upload a photo of the wiring, but apparently I don’t have permission to upload a photo, and it doesn’t show up as an option anywhere that I can see.

[Markjosephp]

Hello there,

I'm dropping by to see how I can help.

I appreciate your help here, Archie.

I'm sorry for the late reply, and thanks for trying, @jacksonland. The labels on your thermostat might have been blocked by the wires in the terminals. Could you at least please tell us which terminals and what color of wires are connected to your thermostat?

I'll look forward to your response.

Best regards,

Mark

[jacksonland]

Thanks for responding. Hoping to post an image, but I get a red bar at the bottom of the post saying,  "You do not have permission to upload images."
The top terminal, has 4 connections, left to right.
The first top terminal screw has a blue wire that connects to the the third screw of a bottom terminal below it (which has three screws).
The second top screw has a red wire that connects to the fourth screw of the same top terminal.
The fourth top screw also connects to the first screw of the bottom terminal.
A white wire from the wall connects the the bottom terminal second screw.
A blue wire from the wall connects to the bottom terminal third screw.
Thank you for any help.

Bill

[jacksonland]

[Markjosephp]

Hello there,

Thanks for sharing the photo and how the wires are being labeled. It appears that you have two jumper wires connected on both heating and cooling ports and no power wire on the R terminal. With this, your system might need to be rewired by a professional installer to be compatible with the Nest thermostats.

Feel free to let us know if you have more questions.

Regards,

Mark

[jacksonland]

Hi Mark,

Thank you for your response. I think we will just hold onto the Nest thermostat, and use it at the next place of residence for one of the family members.

Thanks,
Bill

[Markjosephp]

Hello jacksonland,

I understand. I appreciate you keeping up with your Nest thermostat. If you have any other concerns or questions, please let me know. Otherwise, this thread will be locked within 24 hours.

Thanks,

Mark