Is this 2 or 3 wire thermostat setup?

Reply

  #1  
Old 04-24-17, 04:24 PM
J
Member
Thread Starter
Join Date: Jul 2016
Posts: 13
Received 0 Votes on 0 Posts
Question Is this 2 or 3 wire thermostat setup?

I want to install a new thermostat and some state they require a 3 wire, and some a "C" wire, and some say a "2 wire" is fine. I am thinking I have a 2 wire but can somebody confirm this?

Name:  IMG_20170424_180222.jpg
Views: 2398
Size:  24.1 KB

If in fact it is a 2 wire, is there a way to convert it to 3 wire?

Thanks in advance.

jim
 
  #2  
Old 04-24-17, 04:30 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,956
Received 1,353 Votes on 1,251 Posts
Welcome to the forums.

Red + white + green = three wires.

Your stat is currently set up for two wire heat.
You should be able to connect the green wire at the furnace end for C use.

Go to the furnace and look where the wiring connects. There should be a C terminal.
If not... shoot and post a few pics pf what you see. http://www.doityourself.com/forum/el...-pictures.html
 
  #3  
Old 04-24-17, 08:25 PM
J
Member
Thread Starter
Join Date: Jul 2016
Posts: 13
Received 0 Votes on 0 Posts
Ahhh, I see. Thank you. So this is what I see at the Zone box:

Name:  IMG_20170424_222255.jpg
Views: 369
Size:  51.0 KB

So I see the green wire on both ends. What I don't see is a place to tie it in at the zone box unless is shares a terminal with the white or red.

Jim
 
  #4  
Old 04-24-17, 08:44 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,956
Received 1,353 Votes on 1,251 Posts
Ok.... this pops up about once a month.

I need a picture of the entire control.
Do you have a meter ?

Your control has T T ..... not R and W. Those red and white wires are connected arbitrarily.
With the meter I'll tell you how to ID them and locate C.

If this is your exact box.... including the terminals in red and blue .... then I don't need a picture.

Name:  SwitchingRelay.jpg
Views: 518
Size:  47.3 KB
 

Last edited by PJmax; 04-24-17 at 09:00 PM.
  #5  
Old 04-24-17, 09:15 PM
J
Member
Thread Starter
Join Date: Jul 2016
Posts: 13
Received 0 Votes on 0 Posts
Ok, that looks like mine:

Name:  IMG_20170424_231227.jpg
Views: 306
Size:  50.5 KB
 
  #6  
Old 04-24-17, 09:21 PM
J
Member
Thread Starter
Join Date: Jul 2016
Posts: 13
Received 0 Votes on 0 Posts
The lower left:


Name:  IMG_20170424_231302.jpg
Views: 343
Size:  49.0 KB


That appears to be the same as your pic
 
  #7  
Old 04-24-17, 09:23 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,956
Received 1,353 Votes on 1,251 Posts
Ok.... so your stat wires are randomly installed on the TT terminals. We'll need to convert those letters.... TT to R and W. I will help you. It's very easy.

Since this is AC... probe polarity is not important.
We will be working with the board that the stats are connected to.


Attachment 80008

1) Check for 24v at the live R and live C terminals I have labeled in red and blue.
Those are set screws and easy to put probes on.
2) Remove the two wires from the TT terminals on the port the new stat will be on.
3) Leave one probe on live C and touch the other probe to either TT terminal. The one that shows 24vac is the R terminal. The other one is W.
4) Put the probe on live R and the TT terminal you tested as R. There should be 0v.
5) Leave the probe on live R and move to the W terminal. You should measure 24vac.

You're done. Tell me which T terminal is W and which is R.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: