My new thermostat has uses a W,R,Y,G and now a "C". My wiring has only W,R,Y, and G and these are needed.
How do I, or can I add the needed "C" wire? Is it just adding a wire from the transformer? :confused:

(C) depends on the stat. Battery powered ones make (C) an optional connection.

(C) goes to the other terminal of the secondary that (R) does not go to. You should find a few low voltage wires on that terminal (gas valve, fan, and outside AC unit all tied together)

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Originally Posted by Bocaheat

My new thermostat has uses a W,R,Y,G and now a "C". My wiring has only W,R,Y, and G and these are needed.
How do I, or can I add the needed "C" wire? Is it just adding a wire from the transformer? :confused:

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Are you saying that you need a fifth wire that runs from the furnace to the thermostat? If so all you have to do is to just add one 18 gage wire to the four that you already have or you can buy a different wire that has six or more wires and replace the four wire cable that you have now.

Ok. Added the wire but now the Fan will not turn off. I used the "B" terminal for the common. Any ideas what is wrong?

Common may not be marked. There are two wires that go to the outside unit. One is connected to "Y". The other wire will be common.

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Originally Posted by Bocaheat

Ok. Added the wire but now the Fan will not turn off. I used the "B" terminal for the common. Any ideas what is wrong?

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Which fan will not turn off? The indoor fan or the outside fan. Let me know and I can tell you what to do.

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Originally Posted by letmetellu

Which fan will not turn off? the indoor fan or the outside fan. Let me know and I can tell you what to do.

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Inside fan keeps running. Note, the other side of the Blue wire goes to the same common terminal inside the furnace.

Remove the "G" wire from the thermostat. Does the fan turn off?

Let's make this simple. G,R,Y,G and C

Let's leave C out of this temporarily.

When R connects to G, the fan comes ON.

When R connects to W, the furnace turns on: The furnace controls the fan (On and Off)

When R connects to Y, the outside AC unit comes on.

Thermostat oddities:

In heat, the fan is controlled by the furnace, but Turning the fan to the ON rather than the auto position sometimes doesn't work in heat mode. OFF will not turn off the fan - the furnace must do it.

In cool the thermostat controls both the W and G terminals. In order to get cool, both Y and G are connected to R.

When a common is used, there will be 24 VAC between R and C at all times.

Bold items were corrected thanks to EPM.

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Originally Posted by KeepItSimpleStupid

Let's make this simple. G,R,Y,G and C

Let's leave C out of this temporarily.

When R connects to G, the fan comes ON.

When R connects to Y, the furnace turns on: The furnace controls the fan (On and Off)

When R connects to W, the outside AC unit comes on.

Thermosat oddities:

In heat, the fan is controlled by the furnace, but Turning the fan to the ON rather than the auto position sometimes doesn't work in heat mode. OFF will not turn off the fan - the furnace must do it.

In cool the thermostat controlls both the W and G terminals. In order to get cool, both Y and G are connected to R.

When a common is used, there will be 24 VAC between R and C at all times.

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I will try this weekend... I'm on the road. Will let you know how I make out. Appreciate the help. If I can not get it figuredd out, I will include some pictures. Thanks

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Originally Posted by KeepItSimpleStupid

Let's make this simple. G,R,Y,G and C

<snip>
When R connects to Y, the furnace turns on: The furnace controls the fan (On and Off)

When R connects to W, the outside AC unit comes on.
<snip>

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Uhh... KISS, I think you got it backwards. Unless they do it differently in your part of the world.

R to Y calls the compressor, which usually is cooling. If it is a heat pump then the O or B terminal (the type of reversing valve determines which must be used) decides whether it will heat or cool.

R to W calls heat. If it is a heat pump W often is the second stage (W2) or backup heat.

Some systems control the fan from the control board and some from the thermostat. You program your tstat accordingly if it allows you to. Otherwise R to G will call the fan (you had that correct), and the temp limiters will overide the fan call and keep it running until the system is below the limit switch threshold.

Ok, here is what I have found. Please see attachment. When I connect the Yellow wire to "C" the fan inside turns on and stays on. (Thermostat - Furnace) RH-R, G-G, W-W1, Y-Blue wire, and finally C-B.

Sorry, not correct! The "O" and "B" terminal on the Furance are reversed.Attachment 12572

Since the new tstat has Rh, there musct also be an Rc. Rc and Rh MUST be jumpered together.

The instrucion had me insert a jumper for my configuration. I assume that was what it was for.

Unless it was missed can you post the brand and model of your new thermostat?

Ritetemp 6080

If you follow this all should work. Now if the wiring color has not been followed by the original installer then you might have to track down the wiring and start over.

The RiteTemp Support Site - 6080 Technical Support Page

I rechecked the wiring and it seem to be working now. Thanks.

Glad you got it going. Keep the web site for future use if necessary.