Nest Thermostat Installation Help with Heat Pump

[Kyle13]

When I attempt the installation in the nest app it says profesional installation required and won't allow me to go to the next step. I have a Trane heat pump system. The outdoor unit is a Trane XL 16i and the indoor is a Trane XV95. 

The wires I have on my current thermostat are: B, O, G, Y1, W1, W2, R, Y2. OT1, OT2 (For outdoor temperature sensor).

I believe B is my common, which nest calls C. 

I have read that I need to go into the pro setup to ensure I don't damage my heat pump system and change some settings. I cannot find an option to enter that menu, but read that you need a pass code to do it anyways. 

Am I able to install this correctly without having the ability to access the pro setup? Would the R wire go to RH or RC? 

Thank you!

[Eitanros]

Hello @Kyle13, 

Thank you for reaching out to the community. I understand you have compatibility and installation questions. I'm happy to help you!

To provide the most accurate guidance, I'll need some additional information:

• What nest thermostat do you have? 
• Does your system have 2 stage heating and/or cooling?
• Can you provide me with a photo of the old wiring configuration?

In the meantime, here's the information regarding your questions:

• Since you have a heat pump system and the most common orientation is to "O", since the first set up, you can select the information that is not necessary to change through "Pro set up". In order to check the information, no passcode is needed, you can access the "Pro set up" Settings > Pro Set up. 
• If you only have one R wire, you can connect your R wire to either Rc or Rh on the Nest thermostat. Important: Don't connect any jumper wires to the Nest thermostat.

Please, keep me posted. 

Best regards. 

Eitan

[Kyle13]

Yes I do have 2 stage heating and cooling I believe. I only have 1 red wire on the back of the thermostat. I have the nest 3rd generation learning thermostat. 

[Kyle13]

 Here is my original thermostat 

[Eitanros]

Hi @Kyle13, 

Thank you so much for the follow-up information. I appreciate you taking the time to share a photo of your current thermostat. Based on the image, your system is compatible with the Nest Learning Thermostat (4th generation) only.

Following this wiring configuration on the Nest thermostat: 

• Yellow - Y1 
• Brown - Y2
• Green - G 
• Orange - O/B 
• Red - RC 
• White - W1 
• Blue - C 
• Black - * 

Under set up process select the  "*" as "Auxiliary heat". 

Let me know how it goes. 

Best regards, 

Eitan  

[Kyle13]

Why would black not go to W2? And so I need to get rid of the 3rd generation and get the 4th generation? What's the difference? Thank you for the help 

[Eitanros]

Hi @Kyle13,

Thank you for the folow-up information!

Since you have a 2-stage cooling and heat pump system, the black wire needs to be connected to the auxiliary heat terminal, you can manually configure your Nest thermostat to control the auxiliary heat. 

Let me know how it goes. 

Best regards, 

Eitan

[SAWcrimson]

What do you do with the OT1 and OT2 wires from the original thermostat?

[Kyle13]

I put each in a wire nut and didn't use them. They go to the outdoor temperature sensor. Nest uses wifi for the outdoor temperature so they are not needed