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B/C wire?

Linds1220
Community Member

Need help installing 3rd generation Nest Learning thermostat. Current one has these wires: RH, B/C (blue wire), O, G, Y1, W1 and W2. I understand all of them except how to connect the B/C and O wires? Pic in comment section.

5 REPLIES 5

Linds1220
Community Member

Here is a picture of current thermostat:
8C3D0E41-33A0-4560-9B37-6B93AA95F6DB.jpeg

MelbaDT
Community Specialist
Community Specialist

Hey Linds1220, 

 

Thanks for reaching out and for the photo. 

 

It looks like a C wire to me as you don't have a separate C terminal, the color is blue, and you already have an O wire on a separate terminal. If you're unsure, check your thermostat's manual if you still have it or let me know of the make and model of your current thermostat so I could dig deeper into it. 

 

Best, 

Melba

MelbaDT
Community Specialist
Community Specialist

Hey there, 

 

Checking back in — how's it going? Still need our help?

 

Best, 

Melba

I hired a professional to come out and finish the setup. It was the C wire. We have a dual heat thermostat so it got too tricky for me to attempt. Thank you for your reply!

MelbaDT
Community Specialist
Community Specialist

Hey Linds1220, 

 

You're welcome and I'm glad to hear that you now have a working Nest thermostat. I'll consider this as resolved and will go ahead and lock it after a day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the Community.

 

Cheers, 

Melba