I need help replacing a thermostat - DIY Chatroom

feltdog · 11-05-2009, 11:35 PM

I have a Carrier single stage heat pump that goes to a carrier propane furnace when the temperature drops below a certain temperature. As I understand it, which is not very well, there is a temperature gauge in the heat pump that will shut the heat pump off when the temperature drops below 32 degrees or so. The equipment is 15 years old. It came with a Carrier thermostat that is not programmable. The wall plate on the thermostat says Q674L 1454 HH93AZ197. The control part says T874R1384 HH07AQ170. It is wired as follows:

O - Orange wire
W2 - No Wire
C - Blue wire
L - No wire
Y - Yellow wire
R - Red wire
G - Green wire
E - Black wire

I purchased a Honeywell TH8320U1008 that I would like to replace it with. I just want to make sure I don't screw it up when I change it out. I assume I should follow the same color coding but I wasn't sure what to do with the Black wire (Aux. or Emergency). Could someone help me with the correct wiring of the new thermostat and the set-up codes. Some of the the set up questions I'm not sure about. Thanks for any help you can provide.

Houston204 · 11-06-2009, 12:01 AM

O/B = orange
Aux & E = black (use a jumper wire)
C = blue
Y = yellow
Rc & R = red
G = green

option 170 = 7
190 = 0

feltdog · 11-06-2009, 10:40 AM

Houston - Thanks for the information. Can you tell me if the following would also be correct?

200 - 1
210 - 1
240 - ?
250 - ?
260 - ?
270 - 5
340 - 2 Is this the temperature gauge that is in the heat pump?
350 - ?
360 - ?

Houston204 · 11-06-2009, 08:29 PM

200 = 1

210 = ? Do you have a fossil fuel kit? If you do not, you will need the listed C7089U1006 Honeywell outdoor temperature sensor. If you do have an external fossil fuel kit, 210 = 1

240 = this option shouldn't appear since you have already set 170 to 7 (multistage heat pump)

250 = 5 for an 80% furnace (metal vent pipe) or, if you have a 90% furnace with PVC venting, 240 = 3

260 = you do not have a third stage, with 170 to 7 this shouldn't appear

270 = 5 for an 80% furnace (metal vent pipe) or, if you have a 90% furnace with PVC venting, 240 = 3

340 = 0 unless you have the optional Honeywell C7089U1006 sensor

350 = 0 unless you have the optional Honeywell C7089U1006 sensor.
Again, this option will not appear because we will have option 340 at 0.

360 = Again, this option will not appear because we will have option 340 at 0. The fossil fuel kit that you must already have will control this.

If you do have the Honeywell outdoor sensor (not Carrier's) post back for different settings.