Help wiring a new Nest Learning Thermostat


  #1  
Old 04-06-22, 06:38 PM
F
Member
Thread Starter
Join Date: Apr 2022
Posts: 6
Received 0 Votes on 0 Posts
Help wiring a new Nest Learning Thermostat

Hello. I saw few posts regarding this very helpful, but Iím still in doubt with my equip.
I have a Trane XR80 Furnace with a Trane heat pump. Although I could figured it out most wires Iím confused with the black X2 that does e exist on the Nest wire check. Also I could not clearly identify which ones are from heat pump or conventional. For example, not sure if I have W1 and W2 or if W1 os actually O. Thanks a lot for any help.

Current Trane thermostat

Furnace wiring
 
  #2  
Old 04-07-22, 09:54 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,159
Received 2,969 Votes on 2,679 Posts
Welcome to the forums.

You have a dual fuel system.
I would not use the basic nest on this system. (the six terminal model)
You will need to located the splice point where the thermostat connects with the furnace and the outside condenser. I would expect to see the the black and white wires connected there.

 

Last edited by PJmax; 04-07-22 at 10:31 AM.
  #3  
Old 04-07-22, 03:00 PM
F
Member
Thread Starter
Join Date: Apr 2022
Posts: 6
Received 0 Votes on 0 Posts
Tks PJMax to looking into this. I got the Nest Learning Thermostat which has got more than 6 terminal. Man this wiring down here is a mess. I tried to capture here, but itís hard to tell.

I believe that the white that come from the furnace itís connected to the W1 on the Heat Pump. The black is not in use. Itís just rolled into the outer wire as Iím showing

Heat pump panel


Black from furnace


in the pic.
I guess that the black coming from outside heat pump itís connected to X3 on the Heat pump panel. Sorry if I couldnít be more precise. I hope this helps. Let me know if you need more pics or any other details. Thanks!
 
  #4  
Old 04-07-22, 09:56 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,159
Received 2,969 Votes on 2,679 Posts
Heat pump panel ?
I've never seen one like that before.
That looks like a panel used with electric reheats but you have gas.
That may be some type of dual fuel converter. Is there a part or model number on it ?


R/Rc ------------> red ----------> Rc (no jumper)
O ----------------> orange ------> O/B
Y ----------------> yellow --------> Y1
G ----------------> green ---------> G
B ----------------> blue -----------> C
W1 --------------> white ----------> W1
If the black is not connected we'll assume it's not needed.

When you set the thermostat up.... you must tell it that you are using a dual fuel system.
You will be asked to program the heat (W1).....................
Source: gas
Delivery: forced air
Fan: Don't activate

 
  #5  
Old 04-08-22, 07:00 AM
F
Member
Thread Starter
Join Date: Apr 2022
Posts: 6
Received 0 Votes on 0 Posts
Hello again PJmax. Thanks for checking this.

One tech that once came to my house also mentioned that he had never seen one like this. This system is about 19 years old, but works just fine. My intention with the Nest is to control the temperatures from anywhere, my current thermostat doesn't do that. Also to save some money with the learning/away feature. Also my upstairs rooms always doesn't have the same temperature from the main level where the thermostat panel is. I've got a sensor on sales with the nest. I might add others if it works well in the future.

I'll attach some pics related to model and manuals I have. I hope this helps you with this system. Once again thank you so much for your support.



Panel screen heat pump

Manual

Diagram

Diagram

Diagram

Diagram

Diagram
 
  #6  
Old 04-08-22, 08:01 AM
F
Member
Thread Starter
Join Date: Apr 2022
Posts: 6
Received 0 Votes on 0 Posts
Just another thing I forgot to mention. The black wire from the Heat pump panel might not be connected to the furnace, but it doesn't mean that the black wire from the thermostat is not connected to the furnace. I thought that the black from thermostat might possibly be the emergency heating. What are your thoughts on that? Thanks.
 
  #7  
Old 04-08-22, 09:15 AM
C
Member
Join Date: Jul 2009
Location: SE Iowa
Posts: 140
Received 6 Votes on 6 Posts
Just a note of caution on the Nest thermostat and remote sensors - the remote sensors can only be set on very rigid schedules. It doesn't take averages across remote sensors, and it doesn't let you adjust what hours are night, day, etc.
 
  #8  
Old 04-08-22, 11:50 AM
F
Member
Thread Starter
Join Date: Apr 2022
Posts: 6
Received 0 Votes on 0 Posts
Thanks CaddyMac for your input. I'll take that into consideration. If I noticed that the sensor doesn't help much I'll for certain not buy others. Although the Nest learns the temperatures we like, I'm tempted to setup a schedule for that right from beginning.
 
  #9  
Old 04-08-22, 06:17 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,159
Received 2,969 Votes on 2,679 Posts
I don't know how well that will respond with a nest thermostat.
X2 does look like emergency heat (furnace).
It's controlled by an ODT (outdoor temperature sensor) for winter switchover.

It's a bit confusing and there are several wiring differences that can cause different things to happen.
 
  #10  
Old 04-09-22, 07:03 AM
F
Member
Thread Starter
Join Date: Apr 2022
Posts: 6
Received 0 Votes on 0 Posts
Thanks Pete for all support. Iíll give it a try later today and see how the Nest will behave. If I have issues I might just plug the old one and return it. Have a great weekend!
 
 

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