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goldy1 · Sep 1, 2009, 06:01 PM

Hi everyone,

I just bought a honeywell rth221b thermostat. The wires I have coming out of the wall have no labels and are colored as follows: red, green, black, orange and white. I have a gas furnace and central air. The wires were attached to my old honeywell round "manual" thermostat to the corresponding screw labeled with the first letter of the colors of the wires indicated above (I'm pretty sure).

Where should I connect these wires to on the new thermostat--and do I need to connect all of them? The options on the rth221b are: Rh,Rc(which have a jumper), W,Y,G.

Thanks for the help!

hvac1000 · Sep 1, 2009, 08:50 PM

I am sure you labeled the wires form where they came from before removing them as it says to do in the directions. The black and orange could be used for different things on some units.
Since you labeled the wires from where they came from before removal all you have to do is put the RH-RC to RED, G to GREEN, W to White. Now the black and orange only you will know where they came from since they are not exactly standard color code for a gas heat electric A/C unit. I would hate to guess since damage to the thermostat could result.

goldy1 · Sep 2, 2009, 01:04 AM

Thanks hvac, I really appreciate your help. Well, actually I didn't label the wires when I took the old unit off--long story that I won't go into now--but I have attempted to see where the wires go into the furnace unit to get a clue as to where they should go into the thermostat. It appears that at some point the orange wire from the wall was spliced into a yellow wire going into the furnace--so I'm guessing I put the orange wire into the yellow spot on the thermostat?

I also know that when I first took the old thermostat off that when the red and orange wires touched the air conditioning unit would kick on--not sure what that means? It is not doing that now though-don't know why.

Also, I already hooked the red into the rh, the white into the white, the orange into the yellow and the green into the green and it nothing happened--but my pilot light isn't lit either-and I can't seem to figure out how to light it. It is supposed to be automatic when the furnace is 'powered on'-but I can't figure out how to power it on. I don't see a circuit for it on my circuit box.

It appears you are from Ohio by the way. I am in columbus-

Again, I REALLY appreciate your help. I am trying to avoid a service call if at all possible. Thanks

hvac1000 · Sep 2, 2009, 06:51 AM

i also know that when i first took the old thermostat off that when the red and orange wires touched the air conditioning unit would kick on--not sure what that means? It is not doing that now though-don't know why.

It is possible the fuse in the inside unit is defective or the transformer that generates the low voltage power. This could have happened while playing with the thermostat wires while trying to hook them up.

It seems you are still looking for a place to hook up the black wire to also.

Here is what I suggest you do

First make sure that the wires you are hooking up to the thermostat correspond color wise with the terminals on the interior unit AND that any wire splicing that you have (IE orange to yellow) and items like that are properly addressed and connected to the correct terminals.

Once that is done correctly you will need to find out why the interior unit is not generating 24 volts for the low voltage circuit. As mentioned before it could be the transformer or a defective fuse (fuse usually located on the circuit board if so equipped). Note: Always replace the fuse with like same and value.

Now in order to trace down the 24 volt problem you will need a electric meter and know how to use it. If you do not have the tool and knowledge to use it you might have to find someone local to do an ON SITE inspection of the circuit and the repair.

We all have to know our limits and capability's so as to prevent further damage to the system or the new thermostat.

Easy does it with anything electrical. You do not want to end up like old smoky here. LOL

goldy1 · Sep 2, 2009, 06:58 AM

Thanks again for all the help- I feel like I'm getting in over my head a bit--which is what I dreaded--i think I need to find someone capable and reasonable in my area to take care of this problem--

hvac1000 · Sep 2, 2009, 07:39 AM

That seems like a very smart decission on your part.

glenwoodposse · Mar 10, 2010, 08:26 AM

If I can expand on your Pilot light issue/question... I have the same thermostat and my heat seems to have a mind of it's own in regards to turning on. Most of the time it works fine, but occasionally, it doesn't turn on at all. When it is supposed to turn on, it makes the noise like something is working in the attic, but nothing ever comes out of the vent. I suspect that the pilot light is out, but am wondering if this is a common problem. Any suggestions would be greatly appreciated.
Thanks!