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Yet Another Nest Wiring Question

BJC3
Community Member

My original 3rd Gen Nest Thermostat worked perfectly for 3 years and then suddenly lost connection to WiFi due to low power. I replaced the battery but it still needed a charge everyday. I replaced the battery a second time and unfortunately damaged the thermostat, rendering it unusable. Replaced thermostat with a new 3rd Gen and having the same problem, thermostat running out of power. 

Now I’m looking back to my wiring configuration. I don’t have a “C” wire. Wires coming from the Trane HVAC control panel are:

R, W1, Y/Y1, G, B

 

How should these be connected to my Nest thermostat? 3 years ago when I first installed the Nest I was instructed to not connect the B wire. My Nest plate is connected from the HVAC system is shown below:

R - Rc

W1 - W1

Y/Y1 - Y

G - G

B - tapped off

 

Why is my Nest Thermostat no longer being powered? 

1 Recommended Answer

Patrick_Caezza
Platinum Product Expert
Platinum Product Expert

First off, the battery in the Nest Learning Thermostat 3rd Gen is not field-replaceable. The batteries that are sold online are for the 2nd Gen thermostat, which is also not field-replaceable. The only Nest thermostat that has replaceable batteries is the new Google Nest Thermostat.

If the B wire was connected to the B terminal on the original thermostat, then it is the C wire. Just connect it to the C terminal on the Nest. If it was just a spare not connected to anything, then you can use it to make a C wire by connecting it to the C terminal in the Furnace/air handler.

View Recommended Answer in original post

8 REPLIES 8

Patrick_Caezza
Platinum Product Expert
Platinum Product Expert

First off, the battery in the Nest Learning Thermostat 3rd Gen is not field-replaceable. The batteries that are sold online are for the 2nd Gen thermostat, which is also not field-replaceable. The only Nest thermostat that has replaceable batteries is the new Google Nest Thermostat.

If the B wire was connected to the B terminal on the original thermostat, then it is the C wire. Just connect it to the C terminal on the Nest. If it was just a spare not connected to anything, then you can use it to make a C wire by connecting it to the C terminal in the Furnace/air handler.

Jeff
Community Specialist
Community Specialist

Hi BJC3,

I just wanted to jump in real fast to see if you saw Patrick_Caezza's reply and to see if you still needed some help on this or if you were able to get it sorted out. If you are still needing some help, just let us know and we'll be happy to continue helping.

Thanks,
Jeff

BJC3
Community Member

I did. I didn’t find his response particularly helpful. The idea that the battery is not “field replaceable” seems is not correct. Perhaps it was not intended to be field replaceable, but it is and it’s easy enough to do. Unfortunately, I haven’t found the reason why my 3rd Generation Nest worked without issue for +3 years and then was unable to be charged by the A/C unit. In the end I’ll have to add a C wire, but I'm going forward with no firm answers and only feeling frustrated by the whole process. The only advice I got was to not do what I had already easily done but no mention of the wiring. 

EdwardT
Community Specialist
Community Specialist

Hi BJC3,

 

We hear you. Our team is working hard to deliver the best experience for our users — we'll take this as feedback. Keep your eye on the Google Nest Community page https://goo.gle/2JvnMRy for any updates. Check out this link on how to file feedback.

Thanks,

Edward

Jhonleanmel
Community Specialist
Community Specialist

Hey folks,

 

@EdwardT, thanks for the help here.

@BJC3, I wanted to follow up and see if you are still in need of any help. Please let me know if you are still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

Thanks,
Mel

BJC3
Community Member

Thanks for checking in. I’ve isolated it to it not being the Nest, and I rechecked the wiring, that too is set up correctly. It’s come down to something with the unit. Still unexplained, a system that was able to power the Nest Thermostat has suddenly not been able to for the past three months. However, with that being said, I took Patrick Caezza’s advice regarding wiring and attached the extra wire as he suggested. So far the blower or the Nest hasn’t blown up and the thermostat seems to be receiving and holding power. Fingers crossed, that may have been the fix, although it goes against what the Nest wiring instructions were saying to do. Thanks again for checking in. 

Jake
Community Specialist
Community Specialist

Hey BJC3,

 

I am glad to hear you were able to get the device powered back up, and everything seems to be working properly from here. I wanted to check in with you, and let you know that we will keep the thread open for a few more days to ensure you are not running into any problems. If so, please feel free to reach back out here, as I would be happy to review further. 

 

Best regards,

Jake

Jake
Community Specialist
Community Specialist

Hey BJC3,


I wanted to check in with you, and let you know that I will be locking the thread in 24 hours.

 

Best regards,

Jake