Replacing Trane XR401 thermostat with Nest


Old 05-21-17, 05:32 AM
Thread Starter
Join Date: May 2017
Location: USA
Posts: 1
Received 0 Votes on 0 Posts
Replacing Trane XR401 thermostat with Nest

Spent over two hours with NEST support, to no conclusion. They insist my wiring is for a dual-fuel, and the NEST itself defaults to this thus requiring 'professional installation' on the device itself. It is not dual-fuel. It appears to be the use of a cooling signal separate from heat stage1 that stumped them.

I'm looking for advice - will the NEST even work with this Trane heat pump? And, what do I need to do with the NEST device to make that work?

Heat Pump: Trane XR Series 4TWR5024H1000AB (all electric)
Old thermostat: Trane XR401 (TCONT401AN21MA)

7-Wire TRANE Wiring:
Red = 24v hot
Black = Heating 2nd stage
White = Heating 1st stage
Yellow = Cooling
Green = Fan
Orange = SOV
Blue = 24V Neutral

Nest gave me a wiring diagram, but the NEST device interprets this as dual-fuel. After long conversations with NEST techs, they seem to think the NEST can't control the cooling separate from the heat 1st stage? I

Anyone installed an Electric-Only Trane Heat Pump using the NEST 3rd Gen Thermostat?
Attached Images  
Old 05-21-17, 05:31 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 61,398
Received 1,399 Votes on 1,296 Posts
Welcome to the forums.

7-Wire TRANE Wiring:
-------------> NEST
Red = 24v hot ----------------------> Rh
Black = Heating 2nd stage --------> cap off *
White = Heating 1st stage --------> W2/AUX
Yellow = Cooling -------------------> Y1
Green = Fan ------------------------> G
Orange = SOV ---------------------> O/B (program for O)
Blue = 24V Neutral ----------------> C

*It is possible but not likely that you have two stage electric re-heating. You can check at the air handler. My guess..... white and black are connected together at air handler.

You can also post the FULL air handler model number for us to check further..
4TWR5 is the heat pump/condensor model number.

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: