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  1. #1
    Join Date
    Jul 2011
    Location
    NEW YORK
    Posts
    58

    Confused Dehumidification Control

    Dear Forum Friends,
    Need advice and have been off awhile with a sick family member. Do a job where there is a humidity controlled space.
    Main AHU has sup humidiity but no dehumidification sequence in place.

    1-So we have Ret Fan Heat Coil, Humidification Bundle, Coil Coil than supply fan.

    2-As you knew we will supply 62F Sup temp in winter mode, and 55F sup temp in summer mode from the AHU to the boxes. VAV's & CAV boxes where they have HW Reheats.

    3-Each JC Stat is reading Temp and Humidity.

    4-We have one wall mounted humidistat.

    The specs show and elect heater will be used for heating and dehumidification control, submittals show heating will be used for heat and dehumidiification.

    But where?
    a) The main air handler unit has the heating coil before the cooling coil so we cannot dehumidify that way.

    b) Would it be at the box zone itself with programming thru the BAS? We have JC Metasys.


    Just wondering, if there should have been an additional heater within the AHU?

    Fear a supply temp reset at the main unit, and waste energy in the space.

    Would welcome anyone's advice and feed back.

    Sincerely,
    Bob

  2. #2
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    961
    is this a chilled water system?

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,338
    Humidity control with reheat is a waste of energy. Electric reheat is <1 lb. of moisture per KW of electricity. Suggest a high efficiency whole space dehumidifier and a good desigh engineer. High eff. dehus are upto 8 lbs. per KW. Chech out the Ultra-Aire systems.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  4. #4
    Join Date
    Jul 2011
    Location
    NEW YORK
    Posts
    58
    YES

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