Trane XV80 Fan Speed
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  1. #1
    Join Date
    Oct 2007
    Posts
    20

    Trane XV80 Fan Speed

    Could you please assist me in understanding how the XV80 is supposed to work in the heat mode. I have a 2.5 ton x19i condenser, XV80 model TUD080R9V3K (gas), and the TN803 thermostat. In the cooling mode, the Comfort R is brilliant, operates at a very low speed most of the time --- a truly variable speed fan, no noise whatsoever.

    In the heat mode (dip switches set for low airflow setting), the fan speed appears to work just in two speeds: low (Stage 1 heat) and high (Stage 2 heat). The speed in Stage 1 heat appears to be as high as that of the cooling cycle in Stage 2. The speed in Stage 2 of Heat is really annoying noise-wise.

    Should I assume that the heat cycle has no fan speed variabilty built into it to keep the air flowing relatively fast so that the heat exchanger does not get fried. Or is there anything messed up with the furnance fan speed issues?

    Any suggestions for mitigating the noise issue?

    Thanks - JR

  2. #2
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    You are right, in heating there is no "Comfort-R" going.. The heat must be removed from the heat exchanger.

    Now if the air noise is really bad, you may have poor duct design.

  3. #3
    Join Date
    Oct 2006
    Location
    Vallejo, CA
    Posts
    154

    Hmm Enlarge Return

    Is the noise from the supply registers or the return?

  4. #4
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,604
    the heat fan speed is adjustable

  5. #5
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,604
    you need a service tech to adjust it to check temp rise

  6. #6
    Join Date
    Oct 2007
    Posts
    20

    XV80 Fan Speed

    Quote Originally Posted by kellyr24 View Post
    Is the noise from the supply registers or the return?
    It appears to be mainly on the return (on some on the supply side on registers close to the blower)

    --JR

  7. #7
    Join Date
    Oct 2007
    Posts
    20

    Trane XV80 Fan Speed

    Quote Originally Posted by catmanacman View Post
    you need a service tech to adjust it to check temp rise
    There appear to be four speed settings High, Medium, Medium-Low, and Low selectable via dip switch settings. Is there any other way that the tech could adjust the fan speed setting?

    Thanks -JR

  8. #8
    Join Date
    Jul 2006
    Location
    Virginia
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    4,604
    dip 1 2 ac size dip 3 4 airflow 350 400 450 per ton dip 5 6 comfort r on off dip 7 8 heat air flow

  9. #9
    Join Date
    Oct 2007
    Posts
    20

    Trane XV80 Fan Speed

    Quote Originally Posted by catmanacman View Post
    dip 1 2 ac size dip 3 4 airflow 350 400 450 per ton dip 5 6 comfort r on off dip 7 8 heat air flow
    Yep, figured that out. Dip 7 on and dip 8 on gives HIGH airflow (jet engine like), I have it on LOW ie. dip 7 off and dip 8 off (that should get me low air flow, correct?) but still compared with NORMAL air flow on cooling, it appears quite high. But I suspect, that's a design feature?

    Thanks again -JR

  10. #10
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,833
    I have the same furnace. On low fire, the airflow is about like cooling is for my 2 ton. But on high fire, and the furnace is oversized for the house, it does sound like a jet engine. I have those switches set to low as well. Morale of story, don't oversize - but when I put mine in, that was the smallest model. Now they have a 60K version. Fortunately, I could do without high fire and usually have it turned off with a switch.

  11. #11
    Join Date
    Oct 2007
    Posts
    20
    Quote Originally Posted by BaldLoonie View Post
    I have the same furnace. On low fire, the airflow is about like cooling is for my 2 ton. But on high fire, and the furnace is oversized for the house, it does sound like a jet engine. I have those switches set to low as well. Morale of story, don't oversize - but when I put mine in, that was the smallest model. Now they have a 60K version. Fortunately, I could do without high fire and usually have it turned off with a switch.
    Thanks. Quick questions:
    - is the airflow on low fire the same as airflow on LOW Stage 1 or High (Stage 2 cooling). Mine on low in cooling is simply inaudible. Very, very quiet. Per documentation, I assume the fan is working at 30% speed of LOW cool setting.

    - are are sw 7 and sw 8 set to both on?

    Thank you JR

  12. #12
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    Quote Originally Posted by jrhvac711 View Post
    Yep, figured that out. Dip 7 on and dip 8 on gives HIGH airflow (jet engine like), I have it on LOW ie. dip 7 off and dip 8 off (that should get me low air flow, correct?) but still compared with NORMAL air flow on cooling, it appears quite high. But I suspect, that's a design feature?

    Thanks again -JR
    I am a homeowner but have a AUD080R9V4 furnace, very similar. I am fascinated by machinery and how these things work, but won't advise you to do things a pro needs to do. With this furnace I got a "Service Facts" technical manual X340989P09 which describes airflow choices for both your model and mine. Page 12 specifically covers your model. With the "080" furnace size, high stage airflow can be set to...

    1) approx. 1240 cfm on "normal", with a rated temperature rise of 48 degrees F
    2) ~1400 cfm on "high", with rated rise of 42
    3) ~1090 cfm on "low", with rated rise of 55

    With your 2.5 ton XL19i and the usual 400 cfm/ton airflow, your system would flow approximately 1000 cfm. There are options to use lower or higher airflow, but all choices would be equal or less than high stage heating airflow. So yes, it is natural the furnace on high fire will move more air and make more noise.

    >>Dip 7 on and dip 8 on gives HIGH airflow

    My manual does NOT support that. If I am not mistaken you are reading the documentation on DIP switch settings 7-8 wrong, and are set to "high" when you would prefer "low". IMO this just begins to cross the line where asking your pro to set these would be a superior solution. You have paid a pretty penny for the top of the line Trane equipment, let your pro be a consultant and help you out here. In addition to interpreting the manual correctly (and being responsible under his insurance if he makes errors), he just might advise you on something pleasing to reduce your noise level. I am thinking of adding return capacity but there might be other solutions such as return grille modifications.

    Hope this helps -- Pstu

  13. #13
    Join Date
    Oct 2007
    Posts
    20
    1) approx. 1240 cfm on "normal", with a rated temperature rise of 48 degrees F
    2) ~1400 cfm on "high", with rated rise of 42
    3) ~1090 cfm on "low", with rated rise of 55


    >>Dip 7 on and dip 8 on gives HIGH airflow

    My manual does NOT support that. If I am not mistaken you are reading the documentation on DIP switch settings 7-8 wrong, and are set to "high" when you would prefer "low". I am thinking of adding return capacity but there might be other solutions such as return grille modifications.

    Hope this helps -- Pstu[/QUOTE]

    Indeed, thanks for pointing this out. SW7 and SW8 should be ON for LOW airflow setting. I'll be talking to the contractor to discuss in more detail.

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