I want to change my current thermostat to a programmable electric one (no batteries). Could someone verify if it does have a common wire and if all wiring could fit modern thermostats?

Looking at the schematics I can see that there is a common wire present but I want to make sure.

--UPDATE-- If I were to go with Honeywell Touch Wifi (RTH9580) would the following wiring work? I am still missing T and F.

Honeywell touch

B -> C

R -> R

O -> W-O/B

Y -> Y

G -> G

W and X2 (both on)-> W2-Aux/e

T = ?

F = ?

  • I don't see a C wire on the Trane, but you could check in the air handler to see for sure where all the wires terminate. – Tester101 Jun 3 '15 at 2:14
  • I found the manual online here: dar.proflo.com/darmanager/Query?PRODUCT_ID=698925&USE_TYPE=INSTALLATION It does say that it requires a 24volt connection. Isn't B meant for a common wire? Otherwise without a 24 volt connection the the thermostat wouldn't work. At least as far as I understand the process. – Michael Jun 3 '15 at 12:18
  • Check the wiring in the air handler, that will tell you definitively which wires are which. – Tester101 Jun 3 '15 at 13:25

Trane units all use Blue as their 24 volt Common for their control circuits, Common is called this because all the 24 volt circuits return to Common to complete the 24 volt circuits.enter image description here

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