Multiple C wires

[Matt8499]

Hello there,

Hoping you can assist me with an question I have. On my existing thermostat, I have two wires going into 'C' (red and white).

I know how to map th wires to the nest (I think), but I'm not too sure what to do with both of the C wires? Does anyone know? Here is my current and future wiring:

Current:

R = Black

W/Y = Orange

Y/A = Yellow

GI = Blue

Gm = Brown

Gh = Purple

C = Red and Blue

Future Nest Wiring (based on what I read in the manual for 3 speed fans):

R to Rc = Black

W/Y to W1 = Orange

Y/A to Y1 = Yellow

GI to G = Blue

Gm to Y2 = Brown

Gh to * = Purple

C to C = ?????

Any advice would be really appreciated!

Thanks!

[zoeuvre]

Hi Matt8499, 

Thanks for reaching out to us. Let me take a look at this for you. 

I checked your thermostat wires and found that I should recommend you to a Nest Pro to have your Nest Thermostat installed because your system has multiple fan wires. Incorrect installation settings have the potential to harm your system, your Nest Thermostat, or both. Systems with Gl, Gm, and Gh wires are some of the systems that need to be setup by a Nest Pro. 

Let us know if you have any other questions. We're happy to help. 

Best,

Zoe

[Dan_A]

Hey there,

I wanted to follow up and see if you still need 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.

Regards,

Dan

[Dan_A]

Hello again,

We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread.
 

Cheers,

Dan

[Matt8499]

Hi Dan, I responded and welcomed the additional help. Did my post not show up? If you can let me know. I’m included to splice the the two wires currently going into the C port. Also, I know I can contact a nest pro, but that’s not why I’m here.

[zoeuvre]

Hi folks,

@Matt8499, thanks for the follow-up, and I'm sorry for the late response. 

We don't recommend wire splicing since our Nest Thermostats are compatible with 24 V systems only with only one solid copper wire going to each of the Nest Thermostat terminals. If you want to proceed with the Nest Thermostat installation, we highly suggest you contact a Nest Pro instead. 

Best regards,

Zoe

[zoeuvre]

Hey Matt8499, 

I wanted to check and see if you are still in need of any help. Please let me know, as I would be happy to assist, and answer any questions you may have.
 

Thanks,

Zoe

[zoeuvre]

Hello there, 

Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know. 
 

Regards,

Zoe