Comfort-R American Standard and Trane Thermostat Needed

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Old 05-19-18, 10:16 AM
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Comfort-R American Standard and Trane Thermostat Needed

I have an American Standard two stage variable speed furnace AUD120R9V5K
I have a 2 stage TRANE 4TTX6036E1000AA Compressor
and a TRANE 4TXCD050BC3HCAA evaporator.

Diagrams below, the thermostat wiring is from the old one I do not have anymore.

This is a new house to me and the thermostat broke. I installed a Lyric T5 and realized that it is not controlling the variable speed fan (just one quiet, low speed). Further research showed that ideally I should have a thermostat the controls the 2 stage heat and 2 stage cool, the variable speed blower and the Comfort-R humidity management. I did a little research (maybe too little) and bought a "new, old stock" Trane XL900, thinking this was the unit that will control it all. Now, I read the the XL900 is a communicating thermostat and I am not sure that my furnace handles that. (the thermostat has not arrived yet)

I called the local HVAC company that cleaned the system and the said the XL900 would work, but recommended a Nest learning thermostat T300. I called Nest and they said they cannot control a variable speed fan.

I am happy to have the HVAC guy install, setup and program the system but I need help in getting the right thermostat. But, of course during this conversation he said "well, you could just replace the system, it is getting old", personally I am hoping that getting the correct thermostat is a better idea.

WIFI is not important, programming is not important, I just want to make sure I get a thermostat that makes this system work like it was designed. Any ideas? Thanks in advance.
 
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Last edited by cdrat; 05-19-18 at 10:56 AM.
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Old 05-19-18, 11:44 AM
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The Lyric T5 in the manual that I downloaded would do the same job that your other listed options will.

The limitation is the Trane furnace paired with a 2 step scroll compressor.
That marriage will eliminate the dehumidification option.

I would have kept the T5 if it had a Y1, Y2, W1, and W2 terminal.
 
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Old 05-19-18, 11:59 AM
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Thanks for the fast reply!!

I would like to keep the Lyric if it will work. The Lyric is still hooked up but the fan is always on low. I have attached the way it is wired (took two calls to Honeywell to make it work)

It looked as if the Y and the Y2 should be reversed from the setting on the furnace circuit board. That is assuming the purple "YLO" wire from the furnace circuit board should be connected to the "Y2" on the thermostat. Do you think that will give me back the variable speed fan?
 
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Old 05-19-18, 11:59 AM
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The 120K Btu furnace does not list 3 ton AC as an option.

Normally stat Y1 lands on furnace Y.
Stat Y2 lands on furnace BK,
The W14 jumper needs to be addressed,
Jumpers between R and O is also addressed

This might provide too much air flow when matched with a 3 to AC unit.

I wonder if wiring for 50% low speed ( instead of the 70%) wouldn't be the better option with your oversized furnace.

http://www.wolffbros.com/catalog/doc...R9V-Series.pdf


Swap yellow and purple at the stat.


I would also check the furnace dip switches.
SW1 off
Sw2 on
Sw3 off
Sw4 on
SW 5 on
SW6 on
SW7 on
SW 8 on
 

Last edited by Houston204; 05-19-18 at 12:24 PM.
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Old 05-19-18, 12:09 PM
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The early photo was the original thermostat, but the display broke and I threw it away. The latest photo is the Lyric T5 that is now hooked up.
The diagram shows the circuit board on the American Standard furnace. It looks as if the "Y" and "YLO" (on the furnace) are crossed with the "Y" and the "Y2" on the Lyric thermostat.

I think you are right, the wiring on the furnace looks reversed.

I don't know much about the system, the American standard was installed in 2004 and the Trane AC in 2010. I live in Indiana.
 
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Old 05-19-18, 12:30 PM
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It looks as if the dip switches are set up this way, if I photographed the right ones.

I also included a photo of what the actual wires look like.

I am going to go switch wires.

Thanks
 
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Old 05-19-18, 12:32 PM
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I updated my last post.

If your outdoor unit was at least a 3 1/2 ton the wiring should look like this...



If I ran across this setup I would check the delta tee and refrigerant charge before and after making these changes.

I might not wire it this way with a 3 ton condenser because it would deliver too much airflow.

I wonder what is the temperature drop across your indoor coil with low speed and than high speed cooling?
 
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Old 05-19-18, 12:38 PM
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I would also check if furnace Y1 is condenser Y1.

I have seen Y1 and Y2 crossed more than once .
 

Last edited by Houston204; 05-19-18 at 12:56 PM.
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Old 05-19-18, 01:23 PM
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OK, I looked at the compressor.

Lyric "C" connects to Furnace "B" connects to Solid Blue wire at outside unit
Lyric "Y" connects to Furnace "Y" connects to Yellow with Red strip at outside unit
Lyric "Y2" connects to "YLO" at the furnace connects to Yellow with black stripe on outside unit.

I will compare to your diagram.
 
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Old 05-19-18, 01:35 PM
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According to your diagram, the blue wire should go all the way from the thermostat to the compressor. My Blue wire switches to white and then is connected to blue again, OK, that is OK.

OK, it is just Y and Y2 that are mixed up.

I could fix that.
 
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Old 05-19-18, 01:37 PM
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http://www.chapmanair.com/images/pdf...036E-SF-1B.pdf

Yellow / black is Y1
Yellow /red is Y2
 
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Old 05-19-18, 02:21 PM
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OK, changed the wiring to to match the diagram. Everything seems to be working. Thank you so much.

So, we assume that if it gets really hot, the fan speed will increase and the system will be able to catch up, which it has not been able to do up to now. You mentioned that I do not have the dehumidification system because of the compressor they installed. I assume that there is nothing that I can do about this short of installing new components. In your opinion, this Lyric T5 is giving me everything I can get out of this system?

You mentioned the number of tons my system has. Is that something I should do something about? The system is running very quietly right now, I assume I should take it down 6 degrees to see what happens.
 
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Old 05-19-18, 02:45 PM
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I turned the thermostat down 10° and the airflow seems about the same, a very gentle blowing.
 
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Old 05-19-18, 02:51 PM
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That Lyric looks like it will support dehumidification.
The dehumidification terminal in actually still available with your setup.

We want 350 to 400 cfm per ton in high speed.
We want 70 to 80% of that in low speed.

Cutting the jumper will drop blower speed by 20%.

As we are currently wired the airflow for low speed is 50% of high speed.

We can look at the airflow delivered in the furnace manual.
 
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Old 05-19-18, 03:25 PM
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Here is a diagram of all the wires connected to the screw terminals on the furnace board.
 
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Old 05-19-18, 05:19 PM
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That looks wrong to me. Thermostat Y1 should land on furnace Y Lo. Thermostat Y2 lands on furnace Y.
 
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Old 05-19-18, 05:46 PM
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Found This. Perhaps it is helpful?

My eyes glaze over after a while.
 
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Old 05-19-18, 05:55 PM
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Is your condenser Y1, thermostatY1 and furnace Y Lo connected at this time?
 
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Old 05-19-18, 06:05 PM
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My thermostat Y, My furnace Y, and my condenser yellow with black stripe are connected

My thermostat Y2, My furnace YLO, and condenser Yellow with red stripe are connected.
 
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Old 05-19-18, 06:39 PM
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The furnace wire connections need to be moved.
Stat Y = furnace YLo = condenser yellow / black
Stat Y2 = furnace Y = condenser yellow / red
 
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Old 05-19-18, 06:44 PM
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Thanks,

Will do, and get back to you
 
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Old 05-19-18, 07:00 PM
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After you get this system running correctly you will have some wiring experience under your belt.
 
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Old 05-19-18, 07:15 PM
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Yes, this has been great. I am starting to get a handle on this, well, at least I confidently work on it.

I always assumed that the variable speed feature was for quietness and comfort. From what I have read recently though it is really for controlling the humidity during the summer by running the air slowly over the coils. Is the reason the Lyric is not controlling the humidity because it does not have a built in humidistat? The XL900 I ordered has a built in humidistat, but it is a much older product than the Lyric T5. What do you think? Do you think the XL900 or another "humidity controlling" thermostat would be better?
 
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Old 05-19-18, 07:35 PM
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We want 1050 cfm in high speed and 840 cfm in low speed.
Let’s have a looks at the furnace manual again...
 
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Old 05-19-18, 07:40 PM
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1251 cfm in high speed and half that in low speed is the current setting.
High speed is just over 400 cfm per ton. That isn’t too bad but low speed is too low.
We can’t drop blower speed for dehumidification or we will not get enough air for stage 1 cooling.

Now lets see what will we get if we wire as shown in the condenser manual...
 
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Old 05-19-18, 07:44 PM
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It is a 3 ton unit according to the receipt.

Looks like we are off the chart?

What does this mean?
4. FOR VARIABLE SPEED: LOW SPEED AIRFLOWS ARE APPROXIMATELY 30% OF LISTED VALUES."
Also this is way off the calculations.
LOW 350 CFM/TON IS RECOMMENDED FOR VARIABLE SPEED APPLICATION FOR COMFORT & HUMID CLIMATE SETTING:
NORMAL IS 400 CFM/TON:

Do you think we should change these values because the units are mismatched?
 
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Old 05-19-18, 08:54 PM
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We should probably wire as shown in the condenser diagram that I posted.
That would get us 1251 cfm in high speed and 1000 cfm in low speed.

These changes are all made at the furnace.

It is too bad that the 5 ton furnace doesn’t have dip switch options for a 3 ton condenser.
We want 1050 cfm in high speed and 840 cfm in low speed.
 
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Old 05-19-18, 09:09 PM
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So, when they say "variable" what they mean is that you can set is at cfm that you would like, there are just a couple different speeds. One of the other reasons it is unobtrusive is that it "ramps up" slowly.

There is a jumper labeled "W14" that from my photo looks un-cut. In the diagram it is called "W14 BK Jumper"

I could add a jumper between "R" and "O"

But I don't see the reference to 4A7A6, is that a reference to the American Standard Model?

So what you are trying to do is get the best combination of the two speeds? When we make the change from 625 to 1000 cfm, it is not going to be too loud?

Could I change out the circuit board and update the whole control? If not, could a tech do it? Or it that throwing money away?
 
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Old 05-19-18, 09:41 PM
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I was just checking the cfm output with both options.
I would not be very concerned about the noise level of low speed cooling. It will be the quietest of the 4 speeds that your furnace puts out. The loudest will be high stage heat.

A lower fan speed will give you lower humidity in the home. If you get too low, it can result in sweating duct work. Do you have a UV light installed in the supply air plenum?

If the airflow is too low it can stress your compressor. The compressor ends up trying to compress liquid refrigerant instead of vapor. Slugging liquid can result in compressor failure.

High airflow will increase efficiency but it will also result in higher humidity in your home.

This cfm issue is common when a 5 ton furnace is paired with a 3 ton condenser.
 
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Old 05-19-18, 09:52 PM
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I was just checking the cfm output with both options.
I would not be very concerned about the noise level of low speed cooling. It will be the quietest of the 4 speeds that your furnace puts out. The loudest will be high stage heat.

A lower fan speed will give you lower humidity in the home. If you get too low, it can result in sweating duct work. Do you have a UV light installed in the supply air plenum?

I do not, I have researched the Honeywell 1 and 2 light systems but did not know if they were needed in this climate (just north of Indianapolis). So, you would recommend one? I also know they are available to control mold on the coils.

If the airflow is too low it can stress your compressor. The compressor ends up trying to compress liquid refrigerant instead of vapor. Slugging liquid can result in compressor failure.

Interesting

High airflow will increase efficiency but it will also result in higher humidity in your home.

This cfm issue is common when a 5 ton furnace is paired with a 3 ton condenser.

So, do I have a choice? I could have lower cfm and humidity but should install a UV light? Would I stress my compressor?

I could have slightly more efficiency and humidity?

I am all about comfort for my family, but I do not want to be foolish if you think I will need a replacement sooner or more maintenance calls.







 
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Old 05-19-18, 10:36 PM
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I like my UV light but I don’t know if mold is going to grow in sweating ducts up north.
I have never been north of Dallas.
Seems like cold moisture in a dark duct is bad anywhere in the US to me.


Has your unit been running this way since 2004?
I would say that premature compressor failure is not going to occur if it hasn’t happened yet.

There is no great option here. I hear that it hits 20 degrees below zero up there.
While I can see that you will have a greater load in the winter than the summer, I recommend getting a system that is slightly better matched the next time that you replace it.
 
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Old 05-20-18, 06:56 AM
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I have only lived here since Dec. 2017. The owner kept great records though. House built in 1986, American Standard Furnace along with AmST 2A7A1036A1000A (which I think is a 3 ton) and the TXC036C4HPC Evaporator. Along with a Honeywell T8011 (which seems to be basic). The current system was installed in 2010.

Well, I think I have been holding out on you. I just looked inside the furnace door and found these documents. They address the humidistat (cutting the W14 Note: #9) and other settings we are speaking about. It seems as if the wiring change we made yesterday was on target. But, otherwise, I am still over my head.
 
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Old 05-20-18, 08:34 AM
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Great picstures.

Do you have a digital meat thermometer?
A temperature reading across the evaporator coil will tell us if these settings will be within range.

I expect a 16 degree drop in high speed and 25 degrees in low speed.
 
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Old 05-20-18, 08:56 AM
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I do, I have one of those thermapens. What do I do? I have never opened up the evaporator coil.
 
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Old 05-20-18, 09:04 AM
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I don’t open the coil to take these measurements.
I put a 1/8” hole in the return air duct just befor the furnace and I put another in the supply air plenum after the evaporator coil.

Post 10 has a picture that I drew of a horizontal setup.
https://www.doityourself.com/forum/a...vaporator.html

Post 5 has a vertical setup...
https://www.doityourself.com/forum/a...p-ac-coil.html
 
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Old 05-20-18, 09:17 AM
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Got it. So., I crank the AC to go down say 10° F, Give it a couple minutes and take measurements before the filter and after the coil to see what kind of drop in temp we get.

Wait, how do I know if it is high speed or low speed. I have never felt anything but low speed in the house.

Is there any kind of led light that is telling me this?
 
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Old 05-20-18, 09:23 AM
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Yes, that is the easy stage 2 test.

It is harder to test stage 1. You need a 1 degree demand for stage 1.

The thermostat that I install most is the Honeywell Prestige IAQ. It gives you a test option.
I wonder if your model also has this function?

I would expect a blinking LED at the furnace to give you 1 flash for every 100 CFM but I am not sure if your model has this or if you could see it through the peep hole if it is there.


Yep it has a test mode...

https://yourhome.honeywell.com/en/qu...s-of-equipment
 
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Old 05-20-18, 09:34 AM
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Yes, it has 1 flash for every 100cfm

Ok, so I measure both places then turn down thermostat, see if the light is blinking more, then measure again.
 
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Old 05-20-18, 09:40 AM
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https://yourhome.honeywell.com/en/qu...s-of-equipment

I would enter test mode at the thermostat to have better testing control.

It would be great if we new the flashes in stage 1.
That 30% has got to be wrong. Trane classes tell me that it is 50% in low speed.
 
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Old 05-20-18, 10:16 AM
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OK, at stage 1 cooling it goes from 70° to 47° and 1 blink per second
at stage 2 it goes from 70° to 49° and 1 blink per second
 
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