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  1. #1
    Join Date
    Aug 2019
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    1
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    Auditorium high humidity

    I'm a facility manager for a 400 seat auditorium. I'm not the maintenance person and can't control the KCM software. For 5 years or more, the humidity during the summer with the A/C on runs between 75-80%. Room setpoint is 68*F. There is ZERO water dripping down the drain from the evaporator coil. When the space is full of people, the humidity doesn't go down. I've been using a data logger recently.

    I originally thought it was a fresh air issue. Iowa summer. But the fresh air intake is closed at the mixing box.

    There are two sets of pipes coming from the compressor. But I've NEVER seen the second "side" come on from the compressor. It's a Trane system with a Honeywell DA controller and that looks to be set up for 4 stage cooling. But it's like stage 3/4 never come on. (don't quote me on this, could be low room load when empty.) I've spent lots of time watching the thing and feeling pipes lol.

    What the maintenance people have done is put in two 70 pint dehumidifiers ... that does nothing. I've been told this is the best they can do. The problem is, theater equipment is starting to rust. Curtains are damp and starting to smell like mold. Wallpaper is peeling. I was told, you run the events, I'll run the heat ... The building was new in 2009.

    Other than installing a dehumidifier in the system, shouldn't this be able to keep it under 80% even when there are no people? I need to be able to pitch an idea, or have an intelligent conversation with another HVAC company because the maintenance manger has everyone believing this is just how it works. He's said the HVAC installer said it is fine so that's were it gets left ... I mean the inside of the fan box of the AHU is wet and black like soot. That can't be normal.

    I can provide more equipment info and settings if need be.

  2. #2
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    9,473
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    Get out the building and find a new job. Your humidity may be high but the IQ of the mechanic is low. About as low as the IAQ in this facility is.
    Try a mold test or monitor the CO2 levels when the facility is full of people.
    ASHRAE says the %RH should be low 60% to avoid growing biologicals that make people sick. The CO2 levels are suggested to be 1,000 ppm.
    This problem will real bad with the high outdoor dew points till sensitive people will get sick inside the home. The is problem is documented in the ASHRAE IAQ manuals. Becareful you do not lose your job as you create awareness.
    400 occupants will add 100 lbs. of moisture per hour. The building it self needs 100 lbs of dehumidification per day per 3,000 sq.ft. of building when unoccupied to maintain <60%RH.
    Is this a government building? Whole cares?
    Keep us posted and be careful.
    Regards Teddy Bear
    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"

  3. #3
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    22,950
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    Do you have the As Built Documentation?

    For a theater you need a mechanical contractor.

  4. #4
    Join Date
    Jun 2012
    Location
    Northern NV
    Posts
    1,761
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    Curious, does it maintain setpoint when fully occupied?

    As the FM, you should have the authority to access the controls software and also to call in a competent mechanical contractor to assess the system for you...

  5. #5
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
    Posts
    3,476
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    Quote Originally Posted by pecmsg View Post
    Do you have the As Built Documentation?

    For a theater you need a mechanical contractor.
    This.

    And locate the Sequence Of Operations, which should be on the Controls Prints. There should be a statement about dehumidification that will have the humidity setpoint that will put the system in Dehumidify Mode. That number will hopefully give you the advantage in conversations with the Maintenance Manager and, if needed, with your common supervisor. Good luck.
    In honor of RichardL: "Ain't 'None' of us as smart as 'All' of us".

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