Wiring Google nest with no C wire


  #1  
Old 12-06-22, 05:30 PM
B
Member
Thread Starter
Join Date: Dec 2022
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Wiring Google nest with no C wire

I am trying to install a google nest thermostat in my old milwaukee thermoflo furnace; model 1203-B10. I do not have a current C WIRE hooked up at the thermostat. There are 3 wires run to the thermostat, but only 2 are used. Could it be as simple as connecting the unused wire to the TR spot? Would this make it a "c wire" that I could hook up the spot for the C wire on my nest?




 

Last edited by PJmax; 12-06-22 at 05:45 PM. Reason: resized pics
  #2  
Old 12-06-22, 05:35 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,816
Received 3,922 Upvotes on 3,518 Posts
Welcome to the forums.

I had previously resized your pics for the board.
I need to know the three colors of the wires to the thermostat.
 
  #3  
Old 12-06-22, 05:56 PM
B
Member
Thread Starter
Join Date: Dec 2022
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
red, white, and blue run to the thermostat. The White is hooked up to the TH spot. The red goes to a wire nut that is connected to a load wire. The blue is unused


 
  #4  
Old 12-06-22, 06:15 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,816
Received 3,922 Upvotes on 3,518 Posts
Very good.
Your blue wire will connect to the blue wire from the transformer.
The letters in yellow are the system function.

 
  #5  
Old 12-07-22, 03:11 AM
B
Member
Thread Starter
Join Date: Dec 2022
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Should I connect these blue wires with a butt connector? Or use a spade connector and connect that to the the TR terminal?
 
  #6  
Old 12-07-22, 08:14 AM
D
Member
Join Date: Jul 2022
Posts: 12
Upvotes: 0
Received 5 Upvotes on 5 Posts
Butt connectors aren't commonly used for these connections. I would say wire nut would be best, if not then spade connector.
 
  #7  
Old 12-07-22, 08:20 AM
B
Member
Thread Starter
Join Date: Dec 2022
Posts: 4
Upvotes: 0
Received 0 Upvotes on 0 Posts
Could I just connect the 2 wires, or do they both have to go back on the TR terminal?
 
  #8  
Old 12-07-22, 09:22 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 64,816
Received 3,922 Upvotes on 3,518 Posts
You can connect them any way that is convenient.
Personally.... I would replace the TR crimp with both wires.
 
 

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