Trane Comfort-R vs. XL16i
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  1. #1
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    Trane Comfort-R vs. XL16i

    New install of xL16i (two-stage) AC with XV95 NatGas Furnace and T803 Tstat.

    My observation is that Comfort-R applies if AC is single-stage. The furnace install manual shows an "Enhanced" mode profile where blower runs at a reduced "humidity" level (I think it was for 7.5 minutes) at 80% speed before going to 100% to satisfy cooing demand. Its not clear that this applies only to 1-stage outdoor unit. So I watched my new unit.

    With my xL16i I noticed on a call for cool, the first stage of AC is engaged and ran at 80% blower for 10 minutes at which time 2nd stage engaged and blower went to 100%. Note that Tstat setting is 3CPH for 1st stage which gives 10 min ON and 10 min OFF.

    I called Trane Tstat hotline and they said that is how two-stage works that based on 1st stage CPH setting, that after the ten minutes if more cooling needed, 2nd stage engaged. Now since this setup ran 80% for 10 minutes vs. Comfort-R 7.5 minutes, does that imply better humidity removal?? I guess the complication is that two-stage compressor is also running at 75-80% which changes the SHR and hence humidity removal.

    If I was to change cooling CPH to 2, that would be 15 min ON / 15 min OFF, would this improve humidity removal due to longer run times in 1st stage, while resulting is larger temp swings???

    Trying to understand how this 2-stage/Varaible speed/etc all plays together.

  2. #2
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    Quote Originally Posted by wraujr View Post
    New install of xL16i (two-stage) AC with XV95 NatGas Furnace and T803 Tstat.My observation is that Comfort-R applies if AC is single-stage. Its not clear that this applies only to 1-stage outdoor unit.
    comfort-R applies to 2 speed as well

    also i will add, the 16i needs special attention when wiring control voltage!



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  3. #3
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    Did you mean to say 2-stage as in compressor or did you mean 2-speed as in blower. I certainly see how Comfort-R would also work with 2-speed blower (as opposed to VS blower), but what type of blower profile would you have if Comfort-R worked with with 2-stage compressor??? In first stage cooling, blower is already running at 80% so I don't see how "Enhanced" profile would work...

  4. #4
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    xL16i and TCONT803 Wiring

    The units were wired according to the diagram (fig. 8) in TCONT803 installer's guide (which specifically denotes 16 SEER two-stage/step compressor) and the diagram matched a "special" diagram the installer rcvd from Trane. Note that none of this matches diagram in gas furnace install manual.

    The various docs are somewhat confusing. I have added diagram from TCONT803 manual. Do you have an experience to indicate that this diagram is not the correct one??. I have also verified that the jumper (W19??) soldered on the furnace board was cut and the Tsat was set to 2H/2C (think it was parameter 170).
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    Last edited by wraujr; 09-11-2008 at 12:20 PM. Reason: Added diagram.

  5. #5
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    Quote Originally Posted by wraujr View Post
    Did you mean to say 2-stage as in compressor or did you mean 2-speed as in blower. I certainly see how Comfort-R would also work with 2-speed blower (as opposed to VS blower), but what type of blower profile would you have if Comfort-R worked with with 2-stage compressor??? In first stage cooling, blower is already running at 80% so I don't see how "Enhanced" profile would work...


    you were talking about variable speed blowers, so forget a 2 speed blower

    comfort-R ramps the motor up on start up

    comfort-R ramps the motor down on off cycle

    breaking BK should just lower fan speed 20%

    the problem with the 16i and its wiring, it leaves to much room for interperatation

    the wiring diagram you posted looks good except y is not wired to anything from the stat which could

    get confusing for a person inexperienced with the 16i


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    Last edited by Airmechanical; 09-11-2008 at 04:11 PM.

  6. #6
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    Yes, that now makes sense.
    When Tstat calls for 1st stage, BK is open which results in 80% blower. Then on call for 2nd stage (after 10 minutes due to 3CPH setting), BK is engaged since Y2 from Tstat engaged and blower goes to 100%.

    So it also sounds like the "Comfort R" feature is also responsible for ramping VS blower up and down which is happening.

    I agree Ylo being open at furnace board is confusing/concerning...
    But, the T803 tstat diagram, the 4TTX3036 (OD), and the "special" xL16i diagram all match (just the furnace diagram is different).

    No wonder so many report install issues. I imagine mixing xL16i or an xL15i with XV80 or XV90 or XV95 along with existing systems creates quite a number of combinations of wiring.

  7. #7
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    Quote Originally Posted by wraujr View Post
    I imagine mixing xL16i or an xL15i with XV80 or XV90 or XV95 along with existing systems creates quite a number of combinations of wiring.
    nope it's only the 16i that blows peoples mind when they actually figure out how to wire it

    the other thing about the 16i is unlike all other seer system's you cant slow the blower down for extra dehumidification through BK



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  8. #8
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    Who and How Control a BS Furnace Blower

    I've heard that said before and I'm trying to figure out what that means.
    As wired the xL16i in first stage has blower running at 80%, period. When you say "the blower can't be slowed down for humidity control", do you mean you can't get the blower to go to say 50% with the way its wired... BK seems controlled by the Tstat, so if Tsat was Honeywell IAQ could the blower be slowed to say 50% while xL16i in 1st stage??? If humidity became a problem, could the Honeywell IAQ provide better blower control. From the install diagram it looks like HW IAQ does not command VS blower.

    Or, is it the furnace (TUH2B) that does not allow for any blower control other than the 80/20???

    From a technical perspective, how does a tstat provide multiple blower levels. Does the signal on BK become a multi-level voltage or is it some type of digital signal that sends a blower level to the furnace control???

  9. #9
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    Quote Originally Posted by wraujr View Post
    I've heard that said before and I'm trying to figure out what that means.As wired the xL16i in first stage has blower running at 80%, period. When you say "the blower can't be slowed down for humidity control", do you mean you can't get the blower to go to say 50% with the way its wired... BK seems controlled by the Tstat, so if Tsat was Honeywell IAQ could the blower be slowed to say 50% while xL16i in 1st stage??? If humidity became a problem, could the Honeywell IAQ provide better blower control. From the install diagram it looks like HW IAQ does not command VS blower.

    Or, is it the furnace (TUH2B) that does not allow for any blower control other than the 80/20???

    From a technical perspective, how does a tstat provide multiple blower levels. Does the signal on BK become a multi-level voltage or is it some type of digital signal that sends a blower level to the furnace control???
    i don't want to get to technical in this forum, my e-mail is in my profile, leave your phone number if you want to discuss it!



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  10. #10
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    Thanks for the offer. Its just the electrical engineer in me wanting to know how it works. Obviously, the days of on/off signals have passed and some of these signals are approaching the complexity of a serial communications link. Autos have reached the same point. Thanks again.

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