Installing Nest on Trane system


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Old 09-03-15, 02:01 PM
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Installing Nest on Trane system

Hi all,
I feel ashamed of myself seeing I work in IT, and can't figure this (most likely) simple setup out on my own!

Anyways-
I need help hooking up a new stat to a Trane XV90 furnace, I am unsure of the model, but I have attached many photos to help identify it. I currently have a Trane Taystat 340, and I would like to upgrade it to a Nest 2nd generation, I currently have a total of 6 Wires in my wall.

I am also unsure as to what orientation I would need to use. Nest gives me different answers each time I call, but most recently they said to use the B orientation- is that correct?

Thanks!
 
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Old 09-03-15, 02:06 PM
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Will post more if needed. Thanks again
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Old 09-03-15, 03:43 PM
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Welcome to the forums.

This is the important picture....
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The colors need to be confirmed.
G ---> green
B ---> orange
R ---> red
W1 ---> ???
Y ---> ???
W2 ---> blue

In order to find the furnace model number.... you remove the burner access cover where it says XV-90. There will be an ID tag on the inside wall.
 
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Old 09-03-15, 04:38 PM
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Thanks for the reply!
I will post back shortly with the requested information.
 
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Old 09-03-15, 04:48 PM
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W1 is White
Y is Yellow

MODEL: TUY080R9V3W1
 
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Old 09-03-15, 09:55 PM
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Trane's B will be the C terminal on the Nest thermostat.
 
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Old 09-03-15, 11:09 PM
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G -----> green ----> G
B -----> orange ---> C
R -----> red -------> Rh
W1 ---> white ----> W1
Y -----> yellow ---> Y1
W2 ---> blue -----> W2

Good idea to turn power off at furnace while changing the wiring to eliminate shorts and surprises.
 
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Old 09-04-15, 03:00 AM
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Great!
Hopefully I'll be able to install this today.

On a side note-
Nest Support told me to put Red into Rc and to put Orange into O/B
I'm assuming that your instructions are more accurate than theirs.. If you could re-confirm that, that would be great!

Also, What orientation is my unit? O or B?

Thanks again!
 
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Old 09-04-15, 04:38 AM
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Neither.


I see nothing to indicate that you have a heat pump.
The O/B terminal is for heat pump reversing valves.
 
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Old 09-04-15, 06:39 AM
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Nest claims there is a heat pump. I quote them below-
"OLD THERMO : NEST
G : G
Y : Y1
R : RC
B: O/B
W2: W2 AUX

Durring your system set up, it will ask you what Orientation your heat pump is, either O or B. Be sure to Select B. Enjoy your new Nest!"

Also, please see the attached photo as I think I may have a heat pump. Name:  image.jpeg
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Old 09-04-15, 07:07 AM
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I see a high effiency gas furnace and an evaporator coil.

Post the tag of the outdoor unit. (Or just look up the make and model of it)

B isn't for the reversing valve with Trane systems. The Nest guy is mistaken.
 
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Old 09-04-15, 07:37 AM
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Not home at the moment. I will get back to you ASAP.
Off hand I do know (90% sure) it's either an XR11 or (less likely) an XR13
 
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Old 09-04-15, 07:53 AM
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Nest claims there is a heat pump. I quote them below-
That tag simply indicates that the contained evaporator is used for both a heat pump application as well as a traditional Air Conditioner

A heat pump is an air conditioner which is capable of reversing direction and pumping hot air into your house instead of just pumping it out. If your condenser unit outside is running while you have the heat on then you have a heat pump. If it only runs when you are in COOL mode then it is an ordinary AC. If you had a heat pump with your gas furnace then it would be a dual fuel system and I don't believe the 340 supports dual fuel systems

And I'm with huston.... i see nothing to indicate you have a heat pump.
I suspect maybe nest support is going with traditional wire color.... (which is a bad way of doing things). Orange is usually devoted to a heat pump reversing valve, but in your case it appears orange is being used as C (common).

Not withstanding, the B connection on Trane is the Common (C), so if the orange wire is connected to the B on the original stat then it is most likely the common wire.

Never go by wire color. While there is somewhat of color standard in place, there is no written rule to it.
 
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Old 09-04-15, 08:07 AM
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Thanks for the reply.
Can I conclude that the wiring scheme that PJmax was kind enough to supply me is correct?
Both my AC and furnace are able to be used in conjunction with the Nest without issues?

Just a few other questions-
I would choose Gas powered on the nest for fuel type, correct?
Also- I have forced air?
 
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Old 09-04-15, 08:13 AM
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If you have no heat pump (which I'm betting) then PJ is correct.

nest is compatible

Choose forced air gas with air conditioning in your setup.
 
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Old 09-04-15, 08:36 AM
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So I'll choose Gas, Forced Air, then Air Conditioning?
Won't it auto detect the AC?
Once again, sorry for all the silly questions, I'm not good at all with HVAC- so I do greatly appreciate the help everyone is giving me!
 
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Old 09-04-15, 09:16 AM
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The nest will auto detect the A/C on the Y1 terminal.

Nest led me to believe you could use Rc or Rh interchangeably if just one R connection was needed but if they recommended Rc..... that's fine.
 
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Old 09-04-15, 09:22 AM
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Thanks!
So I should have zero troubles/damage to anything if I follow:

G -----> green ----> G
B -----> orange ---> C
R -----> red -------> Rh (But preferably Rc as mentioned by you)
W1 ---> white ----> W1
Y -----> yellow ---> Y1
W2 ---> blue -----> W2

It really won't matter if I use Rc or Rh?
If it was your installation, what would you use?

Thanks again for the help!
 
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Old 09-04-15, 10:38 AM
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The Trane XR13 is available in heat pump or air conditioning.

The beginning of the model number will tell you what it is...

The 4TTR is the air conditioner.
The 4TWR is the heat pump.

PJ's wiring is correct.
I'd use RC but either will work.
 
  #20  
Old 09-04-15, 10:51 AM
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Will the model number affect my wiring scheme that was provided to me by PJmax?
In other words, can I go home and just take the old thermostat off, and put the Nest up, wiring it based off of PJ's wiring regardless if the outside unit says 4TTR vs 4TWR?

Thanks!
 
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Old 09-04-15, 02:35 PM
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You have a gas furnace which means it would be extremely rare to have a heat pump also. Heat pumps are used in areas where there is no fossil fuel available or it is very costly and electric would be less expensive.

We're basing our wiring advice on your old thermostat wiring. If you wire it like we illustrated you should have no problems.

Be sure to shut the furnace off first so that in the event the wires touch nothing will get shorted.

Now... go do it.
 
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Old 09-04-15, 08:50 PM
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Thank you for all of the help. You and Houston have helped me a lot. I will be doing this tomorrow. Will report back
 
 

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