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Brian HVAC Guy
Brian HVAC Guy, HVAC Technician
Category: HVAC
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Experience:  I have been an HVAC/R mechanic/technician for 30+ years.
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Having trouble converting trane thermostat to nest. Using a

Customer Question

Having trouble converting trane thermostat to nest. Using a heat pump. The x2 wire has no place to go. Has both B and O wire
Submitted: 1 year ago.
Category: HVAC
Expert:  Lee Traxler replied 1 year ago.

Your B wire will no longer be used.

Expert:  Lee Traxler replied 1 year ago.

Was I able to help you on this problem?

Expert:  Lee Traxler replied 1 year ago.

Please let me know if that helped and rate me, thanks

Customer: replied 1 year ago.
This did not help at all.
Expert:  Brian HVAC Guy replied 1 year ago.

Hi I'm Brian and I'm here to help! I'm sorry you haven't received the help you need so far. Would you like to continue with me as your expert? I assure you I am well versed in both Trane heat pumps and Nest thermostats.



Customer: replied 1 year ago.
Answer the question I asked
Expert:  Brian HVAC Guy replied 1 year ago.

Very good then. The short answer (without knowing your old thermostat model and what wires went to what terminals) is:

B will go to C on the Nest, this is 24 volt ac common and Trane designates this B while all other mfrs. designate it C. Since you had one on the Trane thermostat, you should connect it to the Nest even though it may not be necessary.

X2 would have been for emergency heat on the Trane thermostat and if you had a connection at W on the old Trane thermostat and transferred it to W/Aux/E on the Nest, then you will tape up the end of the X2 wire and tuck it back in the wall. Newer electronic thermostats don't need a separate terminal for W (or Aux) and E where older ones did.

With all that said, the Trane XL16I is a two stage heat pump so you should have connections on: R, Y, Y2, G, W (Aux/E), C and O and that should complete the needed wires for your system with the Nest thermostat. The Nest should configure your system automatically as a two stage heat pump with auxiliary heating.

Let me know if you have further questions on this subject. Otherwise, please remember to rate before leaving (3 stars or higher please!). Bonuses are always appreciated! Thanks for allowing me to help and thanks for using Just Answer!

Thank you,