Installing Honeywell Wifi Thermostat - G wire to C terminal


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Old 04-12-17, 11:24 PM
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Installing Honeywell Wifi Thermostat - G wire to C terminal

Hi everyone, I dont know much about HVAC's and would really appreciate some help. I am trying to install a new Honeywell Thermostat in our apartment that has centralized AC. My old thermostat had a G wire and no C wire and the Honeywell manual said to put the G wire into the C terminal. Then, also move the G wire to the C terminal on the cooling and heating unit's board and put a jumper cable on the Y and G terminal as well.

I'm not surr what to do because I dont see any letters on the overhead unit as seen on the picture. How can I install the thermostat correctly? Thank you in advance. Name:  IMG_6194.jpg
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Old 04-12-17, 11:50 PM
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Welcome to the forums.

We keep one topic in one thread so your other post in the second thread is gone.

We need to know what that is there. That is not a standard split A/C system.
We need to know it's make and model number.

or we need the make and model of the old thermostat and what color wire was on each terminal.
 
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Old 04-13-17, 10:50 AM
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I will try to find out the make and model of the ac unit from the management company but the thermostat present now is White & Rodgers 1F78. Here is a photo of it. Pls note there are 2 wires in Y terminal.
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Old 04-13-17, 10:53 AM
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And here is a photo of the new thermostat, which has a C terminal.Name:  IMG_6193.jpg
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Old 04-13-17, 02:24 PM
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White & Rodgers 1F78-??? . That's a partial model number.

DO NOT rush to install the new stat. There are questions here yet.

Your stat is currently wired in a heat pump format. It may not be a heat pump but it is using the O (heat pump) terminal.

I see....
G = green
W = white
Rh + Rc = red
Y = ? color

Is Y jumpered to O ?
 
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Old 04-13-17, 05:57 PM
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Question

Hi Pete,

How can I check the complete model #? Coz I only see this on the pic below.

Also, there is no jumper on Y and O. But I see 2 wires plugged into Y.

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Old 04-13-17, 06:15 PM
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So fill in what I started....

what color is on O ?
what colors are on Y ?
 
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Old 04-13-17, 09:28 PM
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Ok here are the wires I saw:

O - White
G - Green
RC - Red
Y - Yellow

There is a Jumper Wire in RC and RH
There is also a Jumper wire in W and Y

Hope this helps.
 
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Old 04-13-17, 09:44 PM
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Just for reference, I believe this is a diagram (Figure 7) from the White & Rodgers 1F78 manual.Name:  IMG_6187.jpg
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Old 04-13-17, 09:47 PM
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I meant to say Figure 4 ...........
 
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Old 04-13-17, 09:50 PM
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Ok....great.

You do have a heat pump system with no back up electric heat.
You must live in a fairly warm area to not have back up/emergency heat.

G = green
Rh + Rc = red
Y = yellow
O = white

We're almost there. We need to locate the C. You've posted two pictures of the wiring.
Can you spread the wiring out and take a few more pictures ?
The C is there I just need to ID it.
 
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Old 04-13-17, 10:00 PM
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We are in Los Angeles.

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Old 04-13-17, 10:05 PM
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I need a picture of the wiring at your A/C end where the blower is. I can't ID the colors.

BUT.... this is good. Look at your cable..... you have a spare blue wire. That will be C.
Try to trim your wires so there isn't so much bare wire. If that shorts you'll lose your system.
 
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Old 04-13-17, 10:20 PM
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Here are the pics thanks
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Old 04-13-17, 10:30 PM
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Ok. So I should use the Heat Pump Terminals of the New Thermostat?

What should I do about the Jumper Cable in Y and W on the old jumper since there is no W Terminal on the Heat Pump Set of Terminals on the new thermostat.

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Old 04-13-17, 10:37 PM
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Sorry.... I can SEE the colors. Too much paint.

Is that the thermostat cable ?
Is the the spare blue wire wrapped around there ?

Look at the A/C comp cable. What colors are connected in it ?

I'll give you the wiring as soon as I see it.
 
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Old 04-14-17, 09:29 AM
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The colors are hardly identifiable coz of the paint. Can i use acetone to wipe of the paint from the wires?
 
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Old 04-14-17, 09:46 AM
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Acetone would probably work.

You don't see any wiring diagram posted there... do you ?


I think I Id'ed the cables correctly. The stat one should have the same colors as at the thermostat.

The other cable should be going to the A/C condensor. That's the one we need the colors.

There should be a yellow, red, white and the C wire.

What large wire colors do you have coming down from the unit ?
In the picture I see yellow, blue, brown.
 
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Old 04-15-17, 06:30 PM
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Ive managed to take better pictures. Hopefully these would help

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Old 04-15-17, 06:39 PM
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Coming from the overhead unit, I see 3 thick wires - Yellow, Blue and Red.

Then I see the YELLOW THICK wire hooked to the GREEN wire
 
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Old 04-15-17, 10:43 PM
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Ok.... I think we're set.

Connect the spare blue wire at the back of the stat to C.

In the picture.... the blue wire in the A/C cond. cable is C.
So that means you need to unwrap the spare blue wire from the stat cable and connect it to the blue wire. You will probably have a connection of 3 blue wires there.

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Old 04-15-17, 11:42 PM
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Thanks So much Pete!

Last, I see a Jumper in Y and W on my opd thermostat. If I use the letters for Heat Pump on my new thermostat, there is no terminal for W. only the Conventional Row has that letter. How do I go about that?


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Old 04-16-17, 12:16 AM
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You will use the heat pump connections.

G = green
R + Rc = red
Y = yellow
O/B = white
C =blue

No Y to W jumper needed.

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Old 04-19-17, 05:24 PM
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Worked like a charm!!! Thank you so much Pete! I really appreciate it.
 
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Old 04-19-17, 06:01 PM
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You're very welcome.

Good job.... you posted good pictures which helped immensely.
 
 

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