Need help with existing wiring for Nest Upgrade

[Mandela64]

Hello,

The existing thermostat controls a gas boiler (Rh & W) and attic air handler (4TEE3F31B1000AA)/ compressor (4A7A6024B1000AA). Looking to see if the blue is my common wire and the brown wire I believe should actually be on Y2. Tracing the wires around, blue goes to B on the air handler and compressor. The brown wire goes to BK on the air handler and yellow/red wire on the compressor.

Honeywell Thermostat

Trane Air handler

Compressor 

[Houptee]

Read this link about Trane BK function

https://www.reddit.com/r/Nest/comments/c95xj5/bk_wire_on_trane_xl624/

[Jhonleanmel]

Hey folks, 

We appreciate your help here, @Houptee.
@Mandela64, 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

[Jhonleanmel]

Hey everyone,

Checking back in should you still have some questions here. Let us know by replying to this thread. 

Best, 
Mel

[Mandela64]

Thank you for everyones help. I haven’t had a chance to install the thermostat yet but i think it should work.

[Markjosephp]

Hi folks,

I wanted to stop by and see how I could help.

I appreciate the followup, @Jhonleanmel.

@Mandela64, thanks for the update. Based on the link shared by Houptee. The BK wire will control your in-home dehumidifier. If your system has a dehumidifier wire, or more than one dehumidifier wire, you might need a professional installation. Also, the blue wire is to the C terminal for Nest, then follow the reset of the wire set up.

Have a look at this article and let us know if you need more help. We would be glad to know what would be the result.

Best regards,

Mark

[Markjosephp]

Hi Mandela64,

I wanted to see if you still needed help. Please let us know if you have any other questions or concerns.

Best regards,

Mark

[Markjosephp]

Hello Mandela64,

Chiming in to check if you have additional questions or concerns as we will be locking this thread within 24 hours.\

Best regards,

Mark