Wiring new thermostat

Old 07-15-14, 07:35 AM
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 1
Received 0 Votes on 0 Posts
Wiring new thermostat

Need help matching my old thermostat wires to my new one. If anybody could help out that would be amazing. I have a heat pump and I'm switching from a old mercury thermostat to a digital. Anyway here what I got. Just need to know where to stick the wires in the new one

Old thermostat. New thermostat
R-red. R- ?
Y-yellow. RC- ?
G-green. Y- ?
E-black. O/B- ?
O-orange. G- ?
X-blue. AUX/E- ?
W2-white. L- ?
Old 07-15-14, 09:19 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 62,066
Received 1,505 Votes on 1,393 Posts
Welcome to the forums.

It's always nice to have the new thermostat model number.

(Turn off power to furnace/air handler when changing wiring)

Red = Rh/Rc
Yellow = Y
Green = G
Orange = O/B
White = Aux/E

E-black = ? emergency heat (tape off-not needed)
X-blue = Common transformer connection (tape off-not needed)

Your new stat will need to be programmed for heatpump operation, etc.

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