Thermostat To Controller Wiring - HVAC - DIY Chatroom Home Improvement Forum

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Old 07-05-2010, 12:01 PM   #1
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Thermostat to Controller Wiring

I went to replace my thermostat with a newer one, and have some questions. The wiring doesnt seem to match up.

First pic is the wiring to thermostat. White was wired to W. Yellow was wired to Y. Green was wired to G. C (common) had no wire. Blue was wired to R. Red was not connected when I took the panel off the wall. I think it may have gotten loose. So I put it on Rc which is jumpered to R.
I immediately wonder why the Blue wire is connected to R.

Now looking at the controller in the basement. The harness coming from the thermostat has the following connections. Blue goes to R. Green to G. Yellow to Y. The White and Red wires are not going to the controller, rather they go down into the blower/boiler. The Red and White wires that are connected to the controller seem to trace by to the A/C unit outside, though Im not 100 percent certain.

So my question is, is this wired correctly? Im confused on how to wire the new thermostat now because im a bit confused by looking at all this now. If this confuses anyone, I can try and explain more or even take better pictures.

Any help is appreciated.


Molson is offline   Reply With Quote
Old 07-05-2010, 06:24 PM   #2
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The red wire, was probably on the R terminal of the stat, not the RC.

You have a dual power source system. One transformer for heat, and one for cooling.

On new thermostat. Remove jumper from RH to RC.


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