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Need advice on hooking up new thermostat please.

Posted by cruzmisl (My Page) on
Tue, Nov 1, 11 at 0:13

Hi All,
I bought a new thermostat that has a separate controller that's mounted near the HVAC equipment. Its not a complex system just a forced air gas furnace and A/C. There are 3 wires between the thermostat and the controller which is self explanatory. The other issue I have is the hookup from the controller to the furnace. I think I have it right but don't want to guess since I can't afford a new furnace:)

Anyway the markings on the furnace are as follows,
Y - Blue wire
G - Green wire
W - White wire
R - Red wire
C - White wire

The wires on the old thermostat are as follows,
Y - Blue wire
G - Green wire
W - White wire
RC - Red wire (there is a jumper installed to R)

I attached a schematic of the new controller. My plan was to disconnect the wires from the furnace, put the controller inline and distribute to the correct terminals.

So,
D1, R-2,C-3 will connect the thermostat to the controller.

Y-White wire
G-Green Wire
W1 (O/B)-white wire (this looked most correct)
R,RC,RH-Red wire. My question is there are jumpers across all three terminals. Do I leave those installed or take them out? Leave some and not others? Not too sure on that.
C- Goes directly to the A/C unit so its not really a component of this install.

If I had two dimes to rub together I'd hire someone but unfortunately for me I can't. Thanks for all the help.

J


Follow-Up Postings:

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RE: Need advice on hooking up new thermostat please.

Sounds as if you have a single stage cooling and heating.

Y is connected to Y. According to your colors, this is blue.
G is connected to G. According to your colors, this is green.
W is connected to W1. According to your colors, this is white, though you seem to have two whites. Hopefully you marked which is which when you took them off the old thermostat.
R is connected to R. According to your colors, this is red. This is the 'hot' or +24v power wire.
C on the furnace goes to C.
I guess you configure the 'stat for 'conventional' operation, in your case AC and gas.


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RE: Need advice on hooking up new thermostat please.

Thanks for the reply. I do have single stage heat and cool. I hooked it all up but it doesn;t work. Its like it has no power so after reviewing the instructions again I cam along another variant of the original schematic. It shows 24V between C and R. Is there an external transformer like a wall wart or is it obtained in the furnace?

Any ideas?


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RE: Need advice on hooking up new thermostat please.

It looks like you have no ground connection going to the controller. I have never done this, but I think you will need to connect a ground from the furnace control board to the thermostat controller. You need to be careful. You are risking both controllers if you make a wrong connection.

I am curious as to why you bought a Visionpro IAQ thermostat. These thermostats are not intended for the do-it-yourselfer.


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RE: Need advice on hooking up new thermostat please.

It came with the whole house dehumidifier.


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RE: Need advice on hooking up new thermostat please.

The 24v comes from the furnace. On the furnace, this is R and C.

Was there nothing connected to 'C' on the furnace?


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RE: Need advice on hooking up new thermostat please.

There was another white wire that was connected to C and R was connected to the thermostat. Here's a pic
A separate wire (from the thermostat wire) is the white connected to "C" and the Black connected to "Y". I never touched those but I think they go out to the AC unit.


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RE: Need advice on hooking up new thermostat please.

Look at the thermostat wire carefully and see if there is another wire available that may have been cut off. It is hard to tell from the picture since the two cables are on top of each other.


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