Nest Gen 3 with Trane XL17i Heat Pump & Variable Speed Air Handler

[Bonedecoy]

I have upgraded my home HVAC system to a Trane XL17i Heat Pump (4.0 ton) and a Trane TEM6 SERIES VARIABLE SPEED FOUR-WAY CONVERTIBLE 48K AIR HANDLER  (TEM6A0C48H41S).  I would like to reinstall my Nest Learning Thermostat 3rd Gen and have 3 questions:

1. Is it compatible?

2. Will I lose any functionality of the of the air handler or heat pump?

3. Is my blue B/C wire B or C based on current thermostat wiring?

I miss my Nest and hate the clunkyness of the user interface of the Trane thermostat (geo fencing, programming, running schedules, etc). I want to install the nest but am hesitant because of some conflicting research I've seen on variable speed air handler compatibility with Nest. 

Thank you for any help!

Rob

[EduardoN]

Hi @Bonedecoy,

Thanks for reaching out! It's wonderful to hear you've upgraded your HVAC system to a heat pump and a Trane TEM6 series air handler. Now that you're looking to reinstall your Nest Learning Thermostat (3rd Gen), I understand you may have questions about compatibility and any potential loss of functionality with your setup. Don't worry, I'm here to help!

To give you the most accurate information, I'd like to ask you the following:

• What wires come out of the base of your HVAC system? If you have a photo, please send it.
• Is your system high voltage or low voltage?
• Does your system have stranded wires?

Please feel free to share any additional details you think might be relevant.

Best regards,
Eduardo

[Bonedecoy]

Hi Eduardo,

Thank you so much for the reply.   Answers to your questions: 99% sure low voltage. Standard thin wire (not stranded); here is the wiring on current thermostat (TCONT824AS52DB):

White Wire - W1

Green Wire - G

Black Wire - Y2

Yellow Wire - Y1

Orange Wire - O

Blue Wire - B/C

Red Wire - RH

Blue Jumper - RH to RC

Thank you so much!

Rob

[Bonedecoy]

 

[Bonedecoy]

Here are several photos of the control board:

    

[EduardoN]

Hi @Bonedecoy,

Thank you for keeping me updated. Regarding your questions, I'd like to share the best wiring options for your system. Yes, you can use the Nest Learning Thermostat (3rd and 4th gen.) and the wiring configuration will be as follows:

• White wire—W1

• Green wire - G

• Black wire - Y2

• Yellow wire—Y1

• Orange wire—O/B

• Blue wire—C

• Red wire—RH

• The blue jumper between RC and RH will not be used.

With this configuration on the Nest Learning Thermostat (3 gen) you intend to reinstall, you will not lose any functionality of the air handler and heat pump.

Let me know if you have any other questions.

Best regards,
Eduardo