Thermostat Wiring - W2/X2 Pin

[crokett™]

trying to decide if my upstairs thermostat is compatible with Nest.  The existing labeling on the Trane thermostat and wiring is

R to red wire
W2/X2 to black wire
W1 to white wire
Y to yellow wire
G to green wire
B to blue wire
O to orange wire

From what I can find, W2 is 2nd stage heat pump, which AFIK I don't have, though I could check the model number.  X2 on a Trane thermostat is emergency heat which would go to * on the Nest, or so says the internet.  The Nest installation site doesn't have anything on the X2 label.  

Will this work?

[Roly]

trying to decide if my upstairs thermostat is compatible with Nest.  The existing labeling on the Trane thermostat and wiring is

R to red wire
W2/X2 to black wire
W1 to white wire
Y to yellow wire
G to green wire
B to blue wire
O to orange wire

From what I can find, W2 is 2nd stage heat pump, which AFIK I don't have, though I could check the model number.  X2 on a Trane thermostat is emergency heat which would go to * on the Nest, or so says the internet.  The Nest installation site doesn't have anything on the X2 label.  

Will this work?

  i think this article will answer your question         LINK    Roly

[crokett™]

That does help. thanks.

[crokett™]

A redux. I can't use the new Nest. It has spots for 6 wires, my thermostat has 7. The new Nest the * is also labeled O/B. I can use it for either the E heat, or the heat pump heat/cool changeover valve but not both at the same time.