Need assistance with old wiring for Nest thermostat

[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: Jai Mistry 

I have a very old Robert Shaw thermostat that I'm trying to replace with a Nest. The wires are not labeled so I am having trouble identifying which ones I have. From the image, it looks like there are 4 wires that come from the wall, but as you can see there are also other wires connected that are not coming from the wall. How do I handle this? Also, based on the colors, it seems to me that I only have a Red, White, Yellow, and Common (blue) wire, but no Green wire from the wall. Does that combination make sense to have?

[rgaila]

Hey there Jai Mistry,

I can definitely understand the confusion when it comes to thermostat issues as it can be very odd to figure out sometimes, but I'm happy to look into this for you. 

First off, I would suggest using the Compatibility Checker to see if your system is compatible. Then, if you need help with installation or wiring, I would suggest contacting a pro to come out to help you with this since I know that the Nest thermostat is not compatible with stranded wires, every wire has to be connected to the Nest Thermostat system. I would also check out this article as it has some good info about identifying wires that work for Nest Thermostat. 

Please let me know if you have any further questions or concerns as I'm happy to help. 

-From Garrett DS, Community Specialist.