Need help installing Trane thermostat

Other Devices & Integrations Climate Control & Temperature Sensors
21

[quote=“integlikewhoa, post:20, topic:181053”][quote=“GoingGreen, post:19, topic:181053”]Integlikewhoa, I am not following your comment about the diagram.

“I have attached the wiring diagram below, one un molested and the other I have circled the 120 to 24v transformer and traced over the common wire as it leads down to the connection block.”

Did you forget to attach the diagram? By “connection block” I am assuming you mean the “polarized plug”.[/quote]

Today your attachments are showing clearly. There must be a bug in the forum software.

No I attached 2 files in that post and as you have found they match the one in your 2nd picture.

I’m assuming the one lower in the pic is the one going to the thermostate. The higher one is going outside to the a/c unit.

Yes, this is correct.

Are you sure it looks like in the picture the blue in the air handler is wire nutted to the blue going to the inside thermostat. Hard to tell as the red wires are in front blocking the picture.

Yes, this is the case. However, the blue and white conductors are cross connected in the two cables.

And you post one or two more pictures with the wires moved around a bit to show me which colors are going to where from both the outside ac and the thermostat

Also the way they have it wired it doesn’t look like you’ll need the 6th wire and it looks so far (waiting for pictures to confirm) that the 24C wire is already hooked up in the air handler to the blue going to the thermostat. So it just might be a matter of putting blue to the 24c in the thermostat and your done.

I specifically right now need to see better shots of the which wires are going to the outside a/c unit. The white wire coming from the thermostat (the heat wire) is wire nutted to?[/quote]

I’ll try to separate the wiring better and take more pictures. Thanks so much for your effort. The digital photos are 5 megapixel and zooming in might help.

22

Got it, I couldn’t see that from the pictures. More pictures from this area with wires moved around a bit will help.

I did zoom in on them, the problem is more some wires covering or are in front of others hard to tell whats happening behind.

I’m still think we going to be good with the 5 wires, but we will have a to move the blue on the thermostat to the RC (which you can do now) and you should see the thermostat power up. After that if we need to make any changes it will be done in the air handler. So I would go ahead and finish the Thermostat and pop it on the wall after you move the blue O wire to the RC spot.

23

This photo should be a bit better. Let me know.

I am anxious to get the unit back in operation because the forecast is for several triple-digit days coming up soon. So far the weather has been on my side.

I will go ahead and remove the Braburn mounting plate, install the Trane mounting plate and connect the red, yellow and green wires since there seems no problem with these. Then when I get an answer back from you I can connect the white and blue. After that all should be good.

24

Reviewing all the posts and pictures again I conclude it all comes down to where the blue conductor should be connected on the thermostat. Is that right?

25

He is hoping he can eliminate the white wire coming from the thermostat … and then reuse it for another purpose.

The hope is that what white wire connects to at the air handler is ultimately the same spot as the blue wire … As I mentioned earlier the blue wire controls the heat/cool switch over. And that in some units power on the blue wire indicates cooling, and in some cases power on the blue wire indicates heating.

@integlikewhoa
Has indicated in his case the power on the blue indicated heating. As a result the blue and white wire were virtually indicating the same thing at the same time. (If he’s wrong than eliminating the yellow wire may be an option, because that means the blue wire follows the same indication as the yellow wire).

I would verify which situation you are in. You need a volt meter … all of the following is low voltage so it’s safe to handle when the power is on. Need to identify the 24V common. You will need this later anyway …
Between the 24V common and the the red wire to the thermostat you should ALWAYS have 24volts.
With the thermostat OFF … you should not have any power between the 24V common and any of the following thermostat wires:
Yellow, Blue, White, Green
Now make the thermostat call for cooling … You should now have 24V between the 24V common and the following thermostat wires:
Red (Always), Yellow (AC), Green (Fan).
You should NOT have power between the 24V common and
Blue(Heatpump SwitchOver) and White(Heat)

If you have power on the BLUE than we need an alternate strategy! If not you are good to proceed!
[hr]
With that knowledge in the Air handler find the wires that connect to the blue wire that goes to the thermostat and the white wire that goes to the thermostat. Disconnect the wire that goes to the white wire to your thermostat and connect it to the same wire nut as the blue wire from the thermostat. (Now all of the blue wires should be connected together!).

Now the white wire from the Thermostat is disconnected (at the air handler). Install the trane thermostat using the same color codes. Except
on the Trane Thermostat change the white wire to the C connector. At the Air Handler you just need to connect the 24V Common wire on the transformer to this white wire on the thermostat.
[hr]
You still have a 50/50 chance that this will work properly without any other changes. At this point your Trane thermostat should be powered.
You need to make the thermostat call for AC … Now is the Air HOT or COLD ? If it’s HOT you need to reverse the polarity of the HeatPump switch over (which controls the blue wire). You need to follow the installers instructions for the Thermostat to do this.

26

Ok, we are making progress. I have installed the Trane mounting bracket and will connect the yellow and green wires to their quick connect points. Power is off at the circuit breaker.

I cannot locate my voltage meter. Drat! It was a very cheap unit and could use a better one so I’ll be off to Lowes this afternoon. When I get back home the saga can continue.

Thanks Richard.

27

GoingGreen, Looking at your last diagram I’m thinking the above could be wrong. I see the common (24C) going from the air handler to the blue wire of #2 (lower) and I’m thinking the outside unit usually has a constant common running to it with the power or hot coming threw the thermostat to the a/c unit.

So I’m thinking that #2 is going to the outside unit and #1 is the thermostat. If that’s the case you don’t have common on the blue wire going to the thermostat currently which means don’t bother moving blue wire around just yet.

Can you make sure where #1 and #2 are going first.

Thanks for the help Richard. I’m looking for a bit more tho. White wire in the top left of the pic. It should be Heat, coming from thermostat (assuming #1 is the thermostat, see above) going to something in the air handler. But unsure why if there is no heat in the air handler and I don’t understand that wire (yet) on the wiring diagram I posted earlier. Whats your take?

If #2 is the thermostat then its running from the air handler to the AC, but I understand that even less.

28

integlikewhoa:

“Can you make sure where #1 and #2 are going first.”

#1 is the cable to the thermostat, #2 is the cable to the outside unit. If you look close at the blue wire nut immediately above #2 you will see where blue and white are cross connected between the cables.

I got my new multimeter, but have not made all the measurements Richard asked for. Had an appointment today and other things slowing me down. It is late afternoon now and my concentration is flagging, so will rest and have supper then make some readings.

29

[quote=“GoingGreen, post:28, topic:181053”]integlikewhoa:

“Can you make sure where #1 and #2 are going first.”

#1 is the cable to the thermostat, #2 is the cable to the outside unit. If you look close at the blue wire nut immediately above #2 you will see where blue and white are cross connected between the cables.

I got my new multimeter, but have not made all the measurements Richard asked for. Had an appointment today and other things slowing me down. It is late afternoon now and my concentration is flagging, so will rest and have supper then make some readings.[/quote]

Ok that’s what I thought. So there is no 24C (2 blues twisted together in the bottom right) going to the thermostat. Eventually we will need to use one of the existing wires or a new wire to the 24C of the thermostat. Let me look over this a bit more.
And It would be nice to get a model number off the outside AC unit or even better a picture of how they have the wires in there. If not the testing of the wires as Richard suggested would also give us an Idea of whats going on.

30

If you are correct about the 24c being the blue wire … then I had the two wires backwards.
With the thermostat removed (the wires can still be screwed to the connectors) See if you have 24Volts between what you have labeled
24C and 24V power.

If your labeling is correct so far … than what you called unsure (white) is currently the heat … That’s the one we will re-use.

The wire nut that is not labeled with the White and Blue wires is the HeatPump Heat/Cool changeover.

==================================================================================================
Forget my previous comments … they would instead be:
Connect the White wire on the unsure wire not, the one that goes to the molex connector, connect that to the unlabeled wire nut … what I called the HeatPump heat/cool crossover. Because that wire is for heat!, but it will get powered from Heat/cool crossover.

Connect the white wire from the thermostat to the 24V common. (Make sure your thermostat is removed before you do this!!!)
Now move the white wire on the thermostat to C on the thermostat for Trane … and the other wires using the same previous color coding.

[hr]
NOTE: The 24V Common wire is the only one you can’t make a mistake with … It’s the one that if connected wrong can cause a problem. So it’s very important that we get that one right! You can short all the other wires together accidentally and the most that will happen is the heat, cool, or fan will come on.

31

I’m 100% sure of the red and blue coming from the Air Handler on the bottom are 24v hot and common verified by the factory wiring diagram.

And him confirming what I thought about which wires go to the thermostat also jive with that.

[quote=“RichardTSchaefer, post:30, topic:181053”]If your labeling is correct so far … than what you called insure (white) is currently the heat … That’s the one we will re-use.

The wire nut that is not labeled with the White and Blue wires is the HeatPump Heat/Cool changeover.[/quote]

Those are both correct, but why are they running the white heat wire to the Air handler and where does it ultimately go in the air handler. The wiring diagram leaves me puzzled on this part.

32

The white wire could be going back to the Heatpump to engage the compressor …
or if it’s the air handler than it could be engaging the fan … because the green wire is typically not engaged for heating. For many furnaces the fan is not turned on for heating until the heat exchanger is warmed … you do not want to blow cold air.

And the crossover controls the 3-way valves to decide on heat or cool operation.

I have not looked at the wiring diagram and I do not remember the default polarity for the Trane thermostate for powering the heat/cool crossover.
So if we are wrong … then when the AC unit calls for cooling … he will actually get heat …
And to fix that requires changing the polarity in the Trane setup and moving a couple wires around … because we will reuse the yellow wire instead of the white wire.

As you correctly observed … for a single state heat/cool heatpump the heat/cool crossover will follow the call for heat/cool.
Actually that’s not 100% true … it true when the thermostat is in Auto mode. He may have to leave the thermostat in Auto Mode.
Some thermostats will power the HeatPump crossover even if the unit does not call for Heat or cool … if the thermostat is placed in the appropriate HEAT or COOL only mode. The idea behind this is the 3-Way valves are pre-positioned for the type of operation anticipated.

33

Richard,

Also they have the green fan and the red 24v also going to the outside unit, which I have never seen a need for either. Also long as we leave them nothing should change, but I’m curious if they even hooked up outside to something or just capped.

I’m thinking the 3 whites need to be need to be hooked together and the 3 blues need to be hooked together only after the blue on the thermostat has been installed on the 24C
This will only work if with the old thermostat the white wire and blue wire have 24v when heat is on. I would test that then the above changes can be made.

34

Well that’s another way … we can re-use the Blue wire as the 24V C … by driving the Cross Over from the Heat pump by the Heat (White) or Cool (Yellow) wire as appropriate.

They Heatpump might drive the Air Handler fan (green wire) to on in heat mode with a temperature/pressure sensor on the return line to the compressor indicating that the coil is warm.

My father was in the business and I did installs and service for him for many years … there are no standards … there are so many ways to accomplish the same thing.

35

Wait this won’t work, we need the compressor to be on no matter heat or cool. Then we need the reversing valve to be on only when in cool.

So doesn’t that mean we need the yellow and the white in the A/C unit to be together and the white or heat from thermostat needs to go to the reversing valve.

More I think about this just run a new wire from the thermostat 24C to the blue wires on the Air handler. LOL

36

[quote=“RichardTSchaefer, post:30, topic:181053”]If you are correct about the 24c being the blue wire … then I had the two wires backwards.
With the thermostat removed (the wires can still be screwed to the connectors) See if you have 24Volts between what you have labeled
24C and 24V power.

If your labeling is correct so far … than what you called unsure (white) is currently the heat … That’s the one we will re-use.

The wire nut that is not labeled with the White and Blue wires is the HeatPump Heat/Cool changeover.

==================================================================================================
Forget my previous comments … they would instead be:
Connect the White wire on the unsure wire not, the one that goes to the molex connector, connect that to the unlabeled wire nut … what I called the HeatPump heat/cool crossover. Because that wire is for heat!, but it will get powered from Heat/cool crossover.

Connect the white wire from the thermostat to the 24V common. (Make sure your thermostat is removed before you do this!!!)
Now move the white wire on the thermostat to C on the thermostat for Trane … and the other wires using the same previous color coding.

[hr]
NOTE: The 24V Common wire is the only one you can’t make a mistake with … It’s the one that if connected wrong can cause a problem. So it’s very important that we get that one right! You can short all the other wires together accidentally and the most that will happen is the heat, cool, or fan will come on.[/quote]

OK, after a few hours sleep I am back on the job. The Braeburn mounting plate was removed and the Trane mounting plate is in place. The thermostat wiring is pulled through and ready to connect.

I have my new digital multimeter powered up. The circuit breaker for the system is off. Checked for voltage at all the leads and they are dead.

Now, is the plan to go ahead and connect all the wiring to the thermostat, set the circuit breaker to on and test voltages inside the air handler with the multimeter? Once I mount the thermostat to the bracket there is no way to probe voltages at the thermostat location.

Depending on what conditions we observe with power on, some adjustments to the wiring inside the air handler may be required.

The most important consideration is the 24v common.

I’m also assuming I will need to perform step 18c of the install instructions which step contains “installer” instructions. I’ll Try to copy that info and attach it to a follow up post because right now my printer will not come out of sleep mode and instructions are to reboot computer, which I don’t want to do at this moment. Basically Step 18c is what conditions the thermostat to control a heat pump.

New photo shows tagged wiring at the Trane connector block.

Awaiting a reply.

37

The Trane connector block is labeled:

24RC G Y1 Y2 24C 24RH W1 W2

38

Do the following:
At the thermostat connect:
Red Wire to RH or RC (They are internally tied together)
Blue Wire to 24C
Green Wire to G
White Wire to W1
Yellow Wire to Y1

Do not install the Thermostat YET!
Back at the air handler …
The Blue wire that is connected to the thermostat wire … that currently goes to the white wire to the heat pump … disconnect those … Hook the Blue Wire from the thermostat to the blue wires of the 24V common wire nut.

----- Lets leave that white wire to the Heat Pump unit disconnected for now …
Turn the Power on … Take your voltmeter and make sure you have 24 Volts between the pair (24C and 24RH) or between the pair (24C and 24RC)
If so … turn the power off again and install the thermostat … than put the power back on.
Your thermostat should now be running.

---- Now turn the thermostat to Auto or Cool mode … and set the thermostat to a low temperature so that it calls for AC.
Your outside unit and inside fan should be running. Wait a minute and check the air temperature. We need to see if it’s blowing hot air or cold air …
It’s going to be one of two cases …
[hr]
If it’s blowing hot air …
Turn of the power … connect that white wire that we left disconnected to the yellow wire nut.
Wait about 5 minutes since the unit was turned off … Then turn on power and make it call for AC again. It should be cold air now.
Turn the Thermostat OFF … Wait about 5 minutes … set to HEAT mode and turn the thermostat to a high temperature …
Wait a few minutes … the Outside unit should be on … The inside unit may not turn on for a few seconds to a minute … in any case in a few minutes it should be blowing HOT air … you are good to go!
[hr]
If it’s blowing cold air …
Great … Now we need to make sure the heat side will work …
Turn off the power … connect that white wire that we left disconnected to the white wire nut (Labeled Heat On)
Wait about 5 minutes since the unit was turned off … Then turn on power. Set to HEAT mode and turn the thermostat to a high temperature …
Wait a few minutes … the Outside unit should be on … The inside unit may not turn on for a few seconds to a minute … in any case in a few minutes it should be blowing HOT air … you are good to go!
[hr]
You may want to test everything one more time … heat mode and cool mode … You should always wait about 5 minutes before turning the outside unit on if it was recently running. Many newer thermostats will have this time delay built int. Many high quality units will also have a build-in timer, or pressure switches, in the outside unit to protect the unit. You should also turn the Heat/Cool/Auto/Off setting to OFF and turn the Fan ON … Then just the inside fan should be running.

39

Looks like a good plan.

The trane by default has a 3 min. Run Time and a 5 min. Off time. So when switching unit on and off or switching from heat to cool. Expect it to run for a bit then delay before it starts back up. These times are adjustable in the trane menu. But the ac unit might also have a safety feature built into too.

40

Connected R G Y B W conductors to the connector block. Red to 24RC, blue to 24C.

Disconnected the blue/white conductors from respective cables and connected the disconnected blue wire to the other blue conductors. All blues are now connected in the air handler. White conductor to outside is free.

I think I mis-interpreted your instructions. The blue conductor in the air handler shouldn’t be wire nutted with the other blue conductors in the air handler.

It seems to me that red on (5) of the polarized plug is what we need to get to 24C. All the red conductors are now wire nutted together. So there should be 24Vac at 24RC on the connector block. As the normal configuration.

When I apply power I do not read 24Vac between 24RC and 24C. Tried range settings from 200 mVrms to 600 Vrms. Nada. Brand new multimeter that I tested reading some 1.5 V batteries and reads ok. I cannot think of any low voltage AC I might test.

The trick is to get 24 Vac to the 24C connector point.

Why not just jumper 24RC and 24C. 24 RC is the hot side of the transformer out?

So will need to work through this issue and try to figure out what went wrong. What I am missing.

Have to break off now because I have an apointment in an hour.