Replacing a Thermostat - http://www.hvacmechanic.com/ Forums

Original message

jgro461

72.146.16.251

"Replacing a Thermostat" , posted Wed 14 May 22:28:

Just bought a Honeywell non programable Thermostat model number (RTH110B). Well the one I had was a Very old TRANE Model # ( 3AAT80B1A1). Ok here is my problem the Trane had seven wires hooked up to it and the new one only has places for five, this might be a simple problem for some but for me it is not. If there is any help that anyone can give me that would be great. I am not sure what all of the wires on the old one are for so if I just had a wiring diagram for it that would help out some. Thank you for your help. Also should I have went with a programable thermostat or is this going to be fine.

Do it yourself

[this message was edited by jgro461 on Wed 14 May 22:40]

Replies:

jgro461

72.146.16.251

"Re(1):Replacing a Thermostat" , posted Thu 15 May 17:35

I have taken some pics of what I have now and what I just bought, so let me know if I am on the right track. I found some lose wires that were in the wall with the other wires not sure what there are for, if you could give me any help there it would be great.

And just incase you can not make out the pic it is a Honeywell RTH7400.

Do it yourself

Houston204

98.196.66.53

"Re(2):Replacing a Thermostat" , posted Thu 15 May 20:08

Rc & R = red (use provided jumper)
O/B = orange
G = green
Y = yellow
Aux & E = white (use a jumper wire)
C = blue
tape off your old brown wire.

option 170 = 7
option 190 = 0

"Tip of the Day" Remember to remove power first.

jgro461

72.146.16.251

"Re(1):Replacing a Thermostat" , posted Wed 14 May 23:35

Thank you very much for your help will go tomorrow and get the other one.

Do it yourself

Houston204

98.196.66.53

"Re(1):Replacing a Thermostat" , posted Wed 14 May 22:58

Your new stat is not compatible with your multistage heat pump. The Honeywell RTH3100C is a non programmable model that is compatible. The Honeywell RTH7400 and RTH7500 (with Autochangeover) are programmable stats compatible with your system.

Note that your old B is now C (common).
Tape off your old T wire.
option 170 = 7 & option 190 = 0 with the RTH7400 and RTH7500.

"Tip of the Day" Remember to remove power first.

Houston204

98.196.66.53

"Re(2):Replacing a Thermostat" , posted Thu 15 May 00:54

If X2 and W were jumpered on your old stat, jumper Aux and E on your new stat.

"Tip of the Day" Remember to remove power first.