Wiring compatibility with Bosch Unit

[WestMichigan]

This is for a Bosch 2 stage heat pump application.  The thermostat below shows the current wiring.  Assuming 2 cooling states, 2 heat stages, and auxiliary heat how would these wire translate?  In particular the white W3 wire.  I think the others are pretty self explanatory.  Ignore the H, DH, and EX contacts since they were never used.  If the H line could be used that would be a plus, but it isn't necessary.

From the Bosch manual

[Jake]

Hey there,

I wanted to follow up and see if I could be of any help. Taking a closer look at the picture provided, I would recommend having an HVAC pro come out, and take a closer look at the system. Please let me know if you have any questions from here, as I would be happy to take a closer look and assist you further. 

Best regards,
Jake

[Jenelyn_O]

Hi there,

Chiming in — 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.

Thanks @Jake for your help.

Best,

Jenelyn

[WestMichigan]

Seems to me like get a HVAC pro is the standard response here.  I was hoping for someone to answer the compatibility question.  I can handle the wiring.

[Jenelyn_O]

Hey WestMichigan, 

Thanks for the update. Could you please provide the model number of your Bosch Thermostat? It will help us to double check the compatibility of your old thermostat to the Nest Learning Thermostat. 

I'll look forward to your response.

Best,

Jenelyn

[WestMichigan]

I have a Bosch CT-80

[Jenelyn_O]

Hi WestMichigan,

Thanks for the follow up information. Nest Learning Thermostat can be compatible with your system, but wires that can only be used for your thermostat are:

• Black wire - C
• Orange wire - OB
• White wire - W1 or W2
• Yellow wire - Y1
• Blue wire - Y2
• Green wire - G
• Red wire - RC or RH

To further check the compatibility, do you mind giving the make and model of your heating and cooling system? 

Best,

Jenelyn

[aatienza]

Hey there,

I just wanted to follow up to see if you still need our help. Please let us know as we would be happy to answer any questions you may have.

I appreciate the help, Jake and Jenelyn.

Thanks,
Archie

[Jake]

Hey there,

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

Best regards,

Jake