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Author Topic: Need help installing Trane thermostat  (Read 29729 times)

Offline integlikewhoa

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Re: Need help installing Trane thermostat
« Reply #30 on: May 14, 2014, 10:53:33 pm »
If you are correct about the 24c being the blue wire ... then I had the two wires backwards.
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.

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.

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.

Offline RichardTSchaefer

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Re: Need help installing Trane thermostat
« Reply #31 on: May 14, 2014, 11:03:59 pm »
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.

 
« Last Edit: May 14, 2014, 11:13:59 pm by RichardTSchaefer »

Offline integlikewhoa

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Re: Need help installing Trane thermostat
« Reply #32 on: May 14, 2014, 11:12:56 pm »
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.

Offline RichardTSchaefer

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Re: Need help installing Trane thermostat
« Reply #33 on: May 14, 2014, 11:20:29 pm »
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.

 

Offline integlikewhoa

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Re: Need help installing Trane thermostat
« Reply #34 on: May 14, 2014, 11:38:34 pm »
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.

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

Offline GoingGreen

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Re: Need help installing Trane thermostat
« Reply #35 on: May 15, 2014, 07:06:40 am »
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.


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.

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.


Offline GoingGreen

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Re: Need help installing Trane thermostat
« Reply #36 on: May 15, 2014, 07:18:05 am »
The Trane connector block is labeled:

24RC G Y1 Y2   24C 24RH W1 W2

Offline RichardTSchaefer

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Re: Need help installing Trane thermostat
« Reply #37 on: May 15, 2014, 09:34:33 am »
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 ...

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!

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!

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.
 

 
« Last Edit: May 15, 2014, 10:34:26 am by RichardTSchaefer »

Offline integlikewhoa

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Re: Need help installing Trane thermostat
« Reply #38 on: May 15, 2014, 10:25:12 am »
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.

Offline GoingGreen

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Re: Need help installing Trane thermostat
« Reply #39 on: May 15, 2014, 03:36:31 pm »
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.

Offline integlikewhoa

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Re: Need help installing Trane thermostat
« Reply #40 on: May 15, 2014, 06:30:24 pm »
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.

That all sound good to that point.

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.
This is incorrect. You should have all three blues together! This will send the common which starts in the air handler to both the outside unit and the thermostat. Which you should now see the thermostat power on.   

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.
The red is the hot side of the 24v. We never want to touch that or cross that with the blues which is the ground, common or negative..... or what ever you want to call it of the 24v circuit.  You should be able to put your meter on a/c voltage with the black on the blue from the air handler and the red on the red of the air handler and you should read 24v or close to it when the breaker for the a/c is on.

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.

Again "24RC" and/or "24RH" are the hot, positive, line what ever you want to call it.  (this is Red)
"C" or "24C" is the negitive, netural, or common. (this is Blue)

Both are different and should not be connected to each other or you will short out the transformer. If you open the hood on your car and you put a screw driver between the positive and negative of the battery this would be the same effect. You need both to complete the circuit but not touching together.
« Last Edit: May 15, 2014, 06:32:08 pm by integlikewhoa »

Offline integlikewhoa

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Re: Need help installing Trane thermostat
« Reply #41 on: May 15, 2014, 06:51:35 pm »
I think I have read that you don't get 24v between the red and the blue coming from the air handler (see first attachment). If that is true then read this. If not ignore the following.

The 24Vac comes from the transformer inside the air handler. You need to test at the air handler molex connector to insure that the miswiring beyond that is not the cause. If you didn't have the 3 blue wires together and you were testing on the side of the thermostat and outside unit and not the side coming from the air handler that would explain it.

If you are testing coming from the air handler side and 24v is not coming I see two issues.

One: (not to insult your intelligence, but) you don't know how or are misusing the multimeter. If we continue to put all 3 blues together and the reds are together and the wiring to the thermostat is (red to RC or RH ) and (blue is the to C) install the thermostat and it should power up. If not, you were correct that you don't have 24V :).

See 2nd attachment

Two: You have already crossed the red with the blues and blown the fuse shown in the wiring diagram below.
Please locate and check for power straight from the 120v to 24v transformer. The low voltage side should have the red and blue wire coming out. The red goes threw a automotive fuse (doesn't say what amperage) then down to the molex connector that you said had no power.
« Last Edit: May 15, 2014, 06:57:42 pm by integlikewhoa »

Offline RichardTSchaefer

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Re: Need help installing Trane thermostat
« Reply #42 on: May 15, 2014, 07:13:11 pm »
The terminology RC and RH come stand for Red Heat (24V Power) and RC Red Cool (24V Power)  when you have two transformers .. one for the heating circuit and one for the cooling circuit. We only have one transformer.   

Make sure your multi-meter is set to measure AC voltage and not DC voltage. A battery is DC voltage.  You can test AC measurement by sticking the two probes into a outlet socket ... you will get 120 Volts.

We really need to verify the 24Volts between the red and blue wires before we proceed.
My eyes are not good enough to read that wiring diagram ... some interesting wires for us are blanked out.

Offline integlikewhoa

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Re: Need help installing Trane thermostat
« Reply #43 on: May 15, 2014, 08:18:31 pm »
We really need to verify the 24Volts between the red and blue wires before we proceed.
My eyes are not good enough to read that wiring diagram ... some interesting wires for us are blanked out.

Richard I already posted this on the 2nd page but here's the wiring diagram without the interesting wires blanked out.

The red and blue are correct and come straight from the low side of the transformer. This is 100% verified.

Offline GoingGreen

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Re: Need help installing Trane thermostat
« Reply #44 on: May 15, 2014, 09:54:09 pm »
I lose concentration after a while and that is the only explanation I can offer for my inappropriate suggestion to jumper 24RC (hot) and 24C (common). I do understand this would be exactly the wrong thing to do. Sorry for the lapse.

Beginning to wonder if it is possible to talk by phone. That might be faster. I don't have a calling plan that lets me make long distance, but I do have Skype and Google Talk. Maybe a Google hangout would work.

I cannot test the multimeter by inserting the probes into a household socket. The probes are too tiny, only about 1/8 inch is exposed.

I did replace the original manufacturers 9 V battery with a Duracell, but see no change because of that. I did probe the connections on the relay in the air handler and get essentially the same result as probing the 24RC to 24C at the thermostat connection block. With the meter set to 20 V resolution I see about 0.05-0.07 and the reading is not steady. This is a digital multi meter.