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  1. #1
    Join Date
    Aug 2006
    Posts
    139
    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

  2. #2
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    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.
    If more government is the answer, then it's a really stupid question.

  3. #3
    Join Date
    Aug 2006
    Posts
    139
    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

  4. #4
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    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?
    If more government is the answer, then it's a really stupid question.

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,889
    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

  6. #6
    Join Date
    Aug 2006
    Posts
    139
    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

  7. #7
    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?

  8. #8
    Join Date
    Oct 2003
    Location
    Washington
    Posts
    7,405
    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...

  9. #9
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    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.
    If more government is the answer, then it's a really stupid question.

  10. #10
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    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 50 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 50 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]
    If more government is the answer, then it's a really stupid question.

  11. #11
    Join Date
    Oct 2003
    Location
    Washington
    Posts
    7,405
    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?

  12. #12
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    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.
    If more government is the answer, then it's a really stupid question.

  13. #13
    Join Date
    Aug 2006
    Posts
    139
    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

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