Trane Pros...Is This Correct

[lksmith]

Greetings,

A couple of weeks ago I had Trane XR13 heatpumps installed with XV80 two stage V/S furnaces in a dual fual application. These were installed with Honeywell IAQ thermostats. Initially the installer forgot to set the dip switches to take advantage of the Comfort R. Another tech came back and fixed the dip switches and also put a jumper across Y and O. I had previously posted a question about the problems I was having prior to the tech coming back out. Mark Beiser was kind enough to comment on the jumpers. At the time I hadn't actually looked to see what the new wiring looked like. I just did that today and here's what I noted.

I have a jumper between Y and O. A yellow wire runs from the Y terminal of the furnace control board to the Y terminal on the tstat interface and then disappears to the the outside unit. From the O terminal on the tstat interface an orange wire disappears down into the outside unit. There is no wire from the O terminal on the tstat interface to the O terminal of the furnace board.

Is that the way it's supposed to be?? There is a note in the installer's guide about connecting the Y and O on the furnace board in a heatpump application, but I didn't know if there was supposed to be a wire from the O on the furnace board to the O on the tstat interface.

I also noted a jumper between W1 and W2. Again, as I read the installer guide it appears to say that the jumper is for use with a single stage thermostat. The IAQ is a 3 stage heat thermostat, shouldn't the jumper be removed in this application?

I'm asking you guys these questions because I hate to pimp the installers for nothing. I hate for them to think I'm checking their work, but I guess I am. I guess my comfort level wasn't that high during the inital install and I just want to make sure this is all done correctly to take advantage of the magic tstats.

On a sort of unrelated question about my IAQ tstats. In the auto-discover mode, the stage 1 compressor rate (220) is 3, the stage 1 heat CPH (240) is 5, and the stage 2 heat CPH (250) is 5. Are these appropriate settings? I thought I had seen some comments on these settings in this forum but I can't remember what the suggested settings were.

Thanks for all your help.

Larry Smith

[mark beiser]

The way they have the jumper from Y to O and the wiring from O on the interface to O outside is fine in most cases.
Wired that way the blower in both the cooling and heating modes, using the heat pump, will run at 50% for 1 minute, then 80% for another 7.5 minutes before ramping up to 100%.

The 80% airflow can cause high pressure problems with the heating mode of the heat pump in mild weather. Personally I don't think there will be a problem with it unless your indoor coil is one of the smaller coils in the range of coils listed for the outdoor unit.

You are correct in questioning the W1 to W2 jumper. The IAQ thermostat can run both gas heat stages in a dual fuel application if wired correctly. No need to jumper W1 and W2 like has to be done with the TH8320.
I would have them wire it correctly.

The cycles per hour look to be set at the default settings. I wouldn't move them off 3 CPH for the compressor and 5 CPH for the gas heat unless there turn out to be problems with those settings.

[lksmith]

Hi Mark,

Thanks for your insights, again!

In your first sentence concerning the Y to O jumpers, and the O to O outside, you said it was fine "in most cases." Is there something I should ask the installers to do differently? (I guess unless they let me remove the W1 W2 jumper, I'm going to have them come back out.)

I don't know how to address your concerns about coil sizes other than to say the I have a 3.0 ton heat pump connected to a 80K furnace and a 2.0 ton heat pump connected to a 60K furnace. Does that help??

Thanks again.

Larry Smith

[mark beiser]

Originally posted by lksmith
I don't know how to address your concerns about coil sizes other than to say the I have a 3.0 ton heat pump connected to a 80K furnace and a 2.0 ton heat pump connected to a 60K furnace. Does that help??

Thanks again.

Larry Smith

What are the model numbers of the indoor coils?

[BaldLoonie]

I've had Comfort R on for 11 years. My pump has a high pressure switch, doesn't trip. Does Trane say don't do it?

Anyway, get the stages hooked up right. But I wonder if the dealer is smart enough to do it and to get into advanced setup and tell the IAQ 2 stages of backup

[lksmith]

Mark,

The coils are: 2TXCB036A (on the 80K furnace) and 2TXCB025A (on the 60K furnace).

Bald,

If you talking about setting up the tstat (installer code 176) Heat/Aux stages, I think we got that right, it auto discovered '2'. If you're referencing something beyond that, I don't know.

Thanks,

Larry Smith

[skeeter_22]

Originally posted by mark beiser
The way they have the jumper from Y to O and the wiring from O on the interface to O outside is fine in most cases.
Wired that way the blower in both the cooling and heating modes, using the heat pump, will run at 50% for 1 minute, then 80% for another 7.5 minutes before ramping up to 100%.

The 80% airflow can cause high pressure problems with the heating mode of the heat pump in mild weather. Personally I don't think there will be a problem with it unless your indoor coil is one of the smaller coils in the range of coils listed for the outdoor unit.

You are correct in questioning the W1 to W2 jumper. The IAQ thermostat can run both gas heat stages in a dual fuel application if wired correctly. No need to jumper W1 and W2 like has to be done with the TH8320.
I would have them wire it correctly.

The cycles per hour look to be set at the default settings. I wouldn't move them off 3 CPH for the compressor and 5 CPH for the gas heat unless there turn out to be problems with those settings.

Since Trane's reversing valves energize in cool..wouldn't the jumper from Y to O energize the reversing valve whenever the condenser came on... even in heat mode ...thus never reversing the gas flow for the heat mode?
Maybe I'm beeing a bone head and didnt understand the problem or the wiring may be different when furnaces are involved? Y=contacter O=reversing valve right?

[seatonheating]

Originally posted by BaldLoonie
I've had Comfort R on for 11 years. My pump has a high pressure switch, doesn't trip. Does Trane say don't do it?

Anyway, get the stages hooked up right. But I wonder if the dealer is smart enough to do it and to get into advanced setup and tell the IAQ 2 stages of backup

That's basic stuff Baldie, are you telling me that installers can't read directions...

[mark beiser]

Originally posted by skeeter_22
Since Trane's reversing valves energize in cool..wouldn't the jumper from Y to O energize the reversing valve whenever the condenser came on... even in heat mode ...thus never reversing the gas flow for the heat mode?

They have O from the thermostat wired directly to O to the outdoor unit without connecting it to O on the furnace control board. The Y to O jumper we are talking about is at the furnace control board, so it won't cause the issue you are asking about.

[mark beiser]

Originally posted by lksmith
Mark,

The coils are: 2TXCB036A (on the 80K furnace) and 2TXCB025A (on the 60K furnace).

Thats not all of the model number. If the 3 ton one is a 2TXCB036AS3HCA, I wouldn't be at all concerned about running Comfort-R in the heat mode with the heat pump.
If it is a 2TXCB036AC3HCA I would like to put my gauges on it and watch it run in the heat mode for a while when it is above 50º outside before I left it running in Comfort-R in the heat mode.

The 2TXCB025A should have S3HCA or C3HCA on the end of it. I think I would want to check the system when it is over 50º outside with either one of them before leaving the system able to run Comfort-R in the heat mode.

There probably won't be an issue with leaving them set up like they are, but if there are any problems during mild weather, the first thing I would do is remove the Y to O jumper and connect O from the thermostat to O on the furnace control board.

Originally posted by seatonheating
That's basic stuff Baldie, are you telling me that installers can't read directions...

Just going off my personal experience, most installers don't seem to know how to read.
Heck, most of the time they just leave the instruction packet for furnaces right where the manufacturer stuck them, usually jamed in against the burner compartment!

[Edited by mark beiser on 10-28-2006 at 11:48 PM]

[seatonheating]

quote:Originally posted by seatonheating
That's basic stuff Baldie, are you telling me that installers can't read directions...


Just going off my personal experience, most installers don't seem to know how to read.
Heck, most of the time they just leave the instruction packet for furnaces right where the manufacturer stuck them, usually jamed in against the burner compartment!

[Edited by mark beiser on 10-28-2006 at 11:48 PM]

That's just plain sad. How the hell do you not know to take the instructions out? Wonder if it has ever burned a house down? Anyone know of that happening?

[mark beiser]

Originally posted by seatonheating
That's just plain sad. How the hell do you not know to take the instructions out? Wonder if it has ever burned a house down? Anyone know of that happening?

I don't know of one causing a house to burn down, but I have found a lot of them that were chared through selveral pages.
The closest to causing an actual fire was one where the instruction book and plastic envelope on a Trane furnace got to smouldering enough for the smell to get sucked into the system through a knockout in the blower compartment that was left sucking attic air.
They smelled something burning, so they shut the heat off and called the fire department.
When I got there, I found the top 1/3 or so of the literature package burned away and scorched paint on the furnace, lol.

[lksmith]

Hi Mark,

The COMPLETE model numbers for the coils are:

2TXCB036AC3HCAA
2TXCA024AC3HCAA

Sorry I didn't get that right on the first try...I assume with those suffixes you would still be concerned about running Comfort R in warmer weather?

As I mentioned in an earlier post, there is a note in the installer guide under "Service Facts" for a UD-V furnace that says:

"7. For heat pump systems Y and O must be connected to the low-voltage terminal board."

Does that mean Y to Y and O to O, or Y and O jumpered on the furnace board? If your answer is Y to Y and O to O, would correctly hooking up those wires alleviate your concerns about the Comfort R in the heat mode?

Thanks,

Larry Smith

[morris nj]

I have an XV80 and a XL14i with a Vision Pro 8320. It was recommended on another post that the CPH for both stages of the heat cycles be changed fron 5 to 3 ??? Just a little comfused.

[mark beiser]

Originally posted by lksmith
As I mentioned in an earlier post, there is a note in the installer guide under "Service Facts" for a UD-V furnace that says:

"7. For heat pump systems Y and O must be connected to the low-voltage terminal board."

Does that mean Y to Y and O to O, or Y and O jumpered on the furnace board? If your answer is Y to Y and O to O, would correctly hooking up those wires alleviate your concerns about the Comfort R in the heat mode?

Yes, that means that the correct wiring per the instructions is to have Y and O from the thermostat connect to Y and O on the furnace control board with no jumpber between Y and O.

Wired that way the blower won't run at 80% for 7.5 minutes in the heat mode of the heat pump like it will the way it is wired now. It will run at 50% for 1 minute, then ramp up to 100%, wich is the way Trane officially wants it to operate.

[mark beiser]

Originally posted by morris nj
I have an XV80 and a XL14i with a Vision Pro 8320. It was recommended on another post that the CPH for both stages of the heat cycles be changed fron 5 to 3 ??? Just a little comfused.

You misread the post.

The default is 3 CPH for the heat pump, and 5 CPH for the gas heat stages. Leave them there unless there is a problem with it set like that.

[lksmith]

OK Mark,

Last question for you then I'll let you go on and have a life other than sorting out my hvac problems.

Is getting this wiring changed a critical event--like it needs to happen NOW, or can it wait a week until I get back in town and can get the techs back out here? I don't want to play DIY but I can if this is a serious issue that needs immediate attention. Temps here in ATL are supposed to be between 45-70 F this next week.

Thanks again for all your help. You have been a real life saver. I must say that I wonder how many other folks have furnace/heat pump installations done incorrectly because either the installer was unfamiliar with the set up or just didn't take the time to look at the schematics.

Larry Smith

[mark beiser]

Originally posted by lksmith
Is getting this wiring changed a critical event--like it needs to happen NOW, or can it wait a week until I get back in town and can get the techs back out here? I don't want to play DIY but I can if this is a serious issue that needs immediate attention. Temps here in ATL are supposed to be between 45-70 F this next week.

I wouldn't call it an emergency situation at all. It is very likely that you will never have a problem if it is left wired the way it is now.
I just prefere to observe a systems operation in mild temps before I leave one wired like that.

I must say that I wonder how many other folks have furnace/heat pump installations done incorrectly because either the installer was unfamiliar with the set up or just didn't take the time to look at the schematics.

Sadly, it is very common.
Most of the time that I work on a multistage/variable speed system I havn't worked on before, I find at leat one thing not per manufacturers specs with the control wiring, dip switch settings, or thermostat setup.
Sometimes it is something that makes sense, like not connecting O to the indoor unit on a heat pump. But usually it is just FUBAR.

[lksmith]

Mark,

I guess my concerns are long term. What if...this issue causes a problem 5-10 years down the road that otherwise would not have occured? There could be expenses that just don't need to happen. I'd rather have it "by the book" than take a chance. I've got a lot of money invested in these new systems, I need them to work a LONG, LONG time!

Thanks again for all of your help. I'll just get the techs back out in the next week or so. Have a good day.

Larry Smith

[mayguy]

Originally posted by mark beiser

Originally posted by morris nj
I have an XV80 and a XL14i with a Vision Pro 8320. It was recommended on another post that the CPH for both stages of the heat cycles be changed fron 5 to 3 ??? Just a little comfused.

You misread the post.

The default is 3 CPH for the heat pump, and 5 CPH for the gas heat stages. Leave them there unless there is a problem with it set like that.

Mark,

3CPH is best for any gas heat, 5 is too short of cycle, and it cycles often. Lot of the guys here has said this else where as well.