Wierd wiring


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Old 09-29-08, 08:03 PM
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Wierd wiring

Moved to a resale house three months ago. Simple heating and cooling.
The house had a white rodgers mechanical thermostat model 1F56W-361.
I bought a brand new Honeywell RTH8500D .
But when i removed my old thermostat.... the wires were not color coded. So i carefully labelled the three wires i found.
As per installation instructions, i did the following
Y-Y
Rh-R+Rc
W-O/B
I put in new batteries and all worked fine. If i take the batteries out the unit dies. I want to power the thermostat from the hvac.
More ... there are two more wires (white and black) that i found ... taped and rolled behind the thermostat. Marked in below images as A and B.



I opened my furnace and saw the two wires were actually connected to the C and the same Y as above.



So i have one C, two Ys, One R, and One W --> coming to the thermostat.

How do i run my thermostat without batteries? Please advice. Also can i convert one black out of the two Ys to a G?

thanks
 
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Old 09-30-08, 07:21 AM
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Great photo!

Thanks!

Ok, the "A" wire, run that to C at the T-stat. (Common)

Do you have A/C?

If you don't have A/C, I would suggest taking that "B" wire and put that on G at the t-stat, and G at the furnace.

Are the black and white wire in it's own group, and other black, white, and red in another group?
 
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Old 09-30-08, 07:25 AM
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Originally Posted by Jay11J
Great photo!

Thanks!

Ok, the "A" wire, run that to C at the T-stat. (Common)

Do you have A/C?

If you don't have A/C, I would suggest taking that "B" wire and put that on G at the t-stat, and G at the furnace.

Are the black and white wire in it's own group, and other black, white, and red in another group?
Yes i have an A/c. and the A & B wire are in one group while the other three are in another group.
 
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Old 09-30-08, 07:32 AM
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Originally Posted by rampageido
Yes i have an A/c. and the A & B wire are in one group while the other three are in another group.
Ok, then be sure to wire up the G wire as well to run the fan in A/C mode.

One thing I do notice is that you don't have an extra set of wire.. (From the unit outside) You will need something hooked up to the furnace to the outdoor unit. Most of the time it's 2 wires for that.
 
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Old 09-30-08, 07:38 AM
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Originally Posted by Jay11J
Ok, then be sure to wire up the G wire as well to run the fan in A/C mode.

One thing I do notice is that you don't have an extra set of wire.. (From the unit outside) You will need something hooked up to the furnace to the outdoor unit. Most of the time it's 2 wires for that.
Thats what i thought. But the fan still runs without the G, when the A/C or heat cycle kicks in. It also runs if i just turn it on. So should i just put the common C on to power the thermostat and leave out the G?

Thanks
 
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Old 09-30-08, 07:46 AM
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You happen to have a Carrier furnace? (model#)

If the A/C ran, is the outdoor unit running?
 
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Old 09-30-08, 08:54 AM
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Originally Posted by Jay11J
You happen to have a Carrier furnace? (model#)

If the A/C ran, is the outdoor unit running?
That i will have to run and get back to you shortly. I don't know the model # yet (will find out) ..... but its a lennox, not a carrier.

Thanks for helping me.
 
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Old 09-30-08, 09:25 AM
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Ok, Will wait for you to get back with the info.

Some Carrier, and maybe Lennox will use a slower blower(heating) speed when you set the t-stat fan switch to fan "ON" rather than the "High" cooling speed.
 
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Old 09-30-08, 05:24 PM
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Originally Posted by Jay11J
Ok, then be sure to wire up the G wire as well to run the fan in A/C mode.

One thing I do notice is that you don't have an extra set of wire.. (From the unit outside) You will need something hooked up to the furnace to the outdoor unit. Most of the time it's 2 wires for that.
When you said there should be two more wires coming from the A/C .... i went looking for the extra wire. It turns out the initial diagnosis of the wires was wrong.

The wires marked A and B in the Fiurnace photo are actually coming from the Air conditioner. The wires marked A and B in the thermostat photo seem to be from the fire place. I can't confirm that a 100%, but thats what it seems to be.

i am getting only three wires (R, Y, and W) from the furnace to the thermostat.

Questions remain -

Programmable thermostats need a power source.... i think i'm stuck with batteries. Is there a drawback of that? Does the thermostat retain its settings after a battery change?

If what i have found is right. Do you think it makes sense to fish another wire from the thermostat to the furnace which can provide the required C and G to run the thermostat without batteries and resolve the fan speed issue you mentioned?

How do i hookup the fireplace ?

I apologize for the wrong interpretation earlier. But thats why i chose this title for my post.


Thanks
 
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Old 09-30-08, 06:25 PM
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Originally Posted by rampageido
When you said there should be two more wires coming from the A/C .... i went looking for the extra wire. It turns out the initial diagnosis of the wires was wrong.
Good thing we did some digging.


The wires marked A and B in the thermostat photo seem to be from the fire place. I can't confirm that a 100%, but thats what it seems to be.
Is this fireplace a gas fired unit? I wonder if the past owner used that for heat source?


Programmable thermostats need a power source.... i think i'm stuck with batteries. Is there a drawback of that? Does the thermostat retain its settings after a battery change?
You can use the battery and there is no drawback on your model. I've told people to make it a habit in the fall when you set your clocks back, change the batteries in the smoke alarm, and t-stat at the same time. Also, if you did forget to change the battery, it will flash "Low Battery" before it goes dead.

No, the t-stat won't lose the settings when you change the batteries.


Do you think it makes sense to fish another wire from the thermostat to the furnace which can provide the required C and G to run the thermostat without batteries and resolve the fan speed issue you mentioned?
It's up to you if you want (can) to fish a new wire, i would do it if I were you.

As for fan speed, it's not an issue... Do you or would like to run the fan? If it turns on the fan speed does run slower in fan ON mode, i would.. I run my mine all winter.

How do i hookup the fireplace ?
I don't think we can... But I'll wait till you post back with more info.

I apologize for the wrong interpretation earlier. But thats why i chose this title for my post.
No need to apologize, that's what we are here for. and glad you posted the photo, able to see what's going on.
 
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Old 10-01-08, 10:09 AM
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Thanks a lot for your feedback. I really appreciate it.

The fireplace is a Regency brand .... i still am struggling on the model # and specs.... but it was installed by the buider... the house is around 7 years old. The gas fireplace is definitely not the primary heating source but it comes with a remote ... its in the family room on the main level. The gas fireplace thermostat has the same black and white wire going somewhere [to the thermostat] ..... the wires also have the same sleeve color as the one behind the thermostat. I could not trace any other wire like that in my whole basement.

I will post the fireplace model # shortly.

Regards
 
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Old 10-01-08, 12:14 PM
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Is this A/B wire hooked up to anything in the fireplace, or just laying there?

If it's hooked up, touch the two wires at the t-stat location, and see if anything happens.
 
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Old 10-01-08, 12:21 PM
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Originally Posted by Jay11J
Is this A/B wire hooked up to anything in the fireplace, or just laying there?

If it's hooked up, touch the two wires at the t-stat location, and see if anything happens.
Its hooked up to the thermostat i think. The round structure next to the on off pilot knob.

But I see your point. Will do that and get back to you.
 
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Old 10-01-08, 12:54 PM
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Originally Posted by rampageido
Its hooked up to the thermostat i think. The round structure next to the on off pilot knob..
Can you post a photo of this? I not sure what this may be.
 
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Old 10-02-08, 12:14 AM
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Originally Posted by Jay11J
Great photo!

Thanks!

Ok, the "A" wire, run that to C at the T-stat. (Common)

Do you have A/C?

If you don't have A/C, I would suggest taking that "B" wire and put that on G at the t-stat, and G at the furnace.

Are the black and white wire in it's own group, and other black, white, and red in another group?
Hmm.. Are you sure it's not the other way around? If you want to be definitely sure, just ask your plumber..
 

Last edited by Jay11J; 10-02-08 at 06:09 AM. Reason: removed link
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Old 10-02-08, 09:14 AM
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Originally Posted by Jay11J
Can you post a photo of this? I not sure what this may be.


Here's the pic of the fireplace. I think the wires marked A & B are going to a valve or something.

I also found this forum through google .....
(link removed)

Regards
 

Last edited by Jay11J; 10-02-08 at 09:27 AM. Reason: Removed link.
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Old 10-02-08, 09:31 AM
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This wire got lost into the walls?

Looks like they were trying to/did use the old t-stat to run the fire place.. But DO NOT hook it up, mixed voltage is going to burn something out.

They may of undone the furnace itself, and hooked up the fireplace by itself, and then swtiched back if they needed heat.

have you fired off the fireplace yet? (don't look like it)

The High and low is the flame size on the fireplace itself.
 
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Old 10-02-08, 10:00 AM
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Originally Posted by Jay11J
This wire got lost into the walls?

Looks like they were trying to/did use the old t-stat to run the fire place.. But DO NOT hook it up, mixed voltage is going to burn something out.

They may of undone the furnace itself, and hooked up the fireplace by itself, and then swtiched back if they needed heat.

have you fired off the fireplace yet? (don't look like it)

The High and low is the flame size on the fireplace itself.

Yes the wires got lost between the walls.

I haven't fired the fireplace yet. But wasnt to sure if i really wanted it hooked to the thermostat and have it turn on automatically. I agree with you and gonna skip the fireplace.

Thanks for all your help. Everything else is working fine. I will contact you again once i fish in the extra two wires and revise the setup again wih you. But i have it clear

C - C
G - G

And that will get me my fan on (without heat and cooling on as well as the power to the thermostat.

Thanks a lot again.
 
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Old 10-02-08, 02:48 PM
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Is the fireplace remote tied to the gas valve?

If it is, I would then remove the two "dead" wires off of that, and tuck that back into the wall since you got a remote that runs the fireplace now.

When you run new wire, i would suggest run 18-8 wire, that way you got the extra wire if you upgrade the system down the road say like Heat Pump, or two stage furnace.
 
 

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