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  1. #1
    Join Date
    Jun 2008
    Location
    NE Illinois
    Posts
    78

    VisionPro IAQ A/C Dehumidify interaction question.

    I have a question on how the a/c and dehumidify interact when both are commanded. When the a/c brings the temperature down to it's desired value and the humidity is still too high does it continue to run the a/c at it's full run speed or does it the drop the speed to the lower fan speed if it's wired for it.
    Since they are relay controlled I plan on hooking both the fan and dehum terminals to the low speed fan setting.

    Thanks

  2. #2
    Join Date
    Jun 2008
    Location
    NE Illinois
    Posts
    78
    Doing more research I found that in the Dehumidify mode it activates the G & Y terminals (fan & cool). The furnace controller will automatically set the fan speed when the Y is activated and ignore the G until the Y turns off.

  3. #3
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    Depends on what's the make/model of furnace and A/C you have.

    I have a single stage A/C on a variable speed furnace, and the blower will run 80% speed if humidity is too high, and if humidity still above set point after the room temp has met temp setting, the system will keep cooling untill set of humidity or cool up to 3˚ below temp set point.

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,741
    Do you have a VS blower?
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    How many times must one fix something before it is fixed?

  5. #5
    Join Date
    Jun 2008
    Location
    NE Illinois
    Posts
    78
    Thanks for the replies,

    I have a Goodman with VS motor, single stage A/C. Fan only will run at 56% of the A/C 100% speed.

    Like with my old system, I assumed that if A/C and Fan is commanded at the same time the furnace controller would run the motor at 100% A/C speed. I'll have to make a phone call and ask although it's probably something that's going to be hard to find out, maybe it will be easier to just try it.

    Thanks again

  6. #6
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,304
    If the dehumidiity is wired up to the furnace, the blower should run slower to remove the humdity in the air.. If it's running 100% when the humidity is above set point, then it's not wired up right.

    Also, if the humidity is 5% above set point, then it will try to "Overcool" up to 3˚ to bring the humidity down.

    Only time the blower run 100% if the humidity is below set point.. (I set mine at 45%.)

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,741
    Call your contractor, and have him come out and check to make sure he wired everything up right.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Jun 2008
    Location
    NE Illinois
    Posts
    78
    Thanks!

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