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  1. #1

    Humidity problems

    Several years ago I purchased a bowling alley with rooftop HVAC units. Heating and air conditioning seems to work, however we always have a humidity problem in the building. Summer time I can easily maintain a cool temperature, but the humidity is terrible. Looking for ideas on what could be the cause. Units have been checked, filters good, everyone baffled........any ideas where to start?

  2. #2
    Join Date
    Apr 2007
    Location
    Upstate NY
    Posts
    107
    Humidity problems are typically caused by oversized equipment. They don't run long enough to dry the air, but cool it off quickly. Try running a couple of the units and shut a couple down to see if they work better. Also if there isn't much ductwork attached to the unit, the fan speed could be to high because no one set it up properly. High airflow causes higher evap. temps whih don't dehumidify as well.

  3. #3
    Join Date
    Mar 2007
    Location
    Madison, Wisconsin
    Posts
    2,260
    Get a load calc done by a quality service co. There could be a number of issues.

  4. #4
    Join Date
    Jul 2007
    Posts
    33
    Quote Originally Posted by Yovert View Post
    Several years ago I purchased a bowling alley with rooftop HVAC units. Heating and air conditioning seems to work, however we always have a humidity problem in the building. Summer time I can easily maintain a cool temperature, but the humidity is terrible. Looking for ideas on what could be the cause. Units have been checked, filters good, everyone baffled........any ideas where to start?
    Agree. Re-calculation of the cooling load must be given priority.

    Re-assessment of the building vicinity must be considered.
    How humid is your ambient condition?

    I suggest take an initial reading of the air properties of the building while all of the units are operational specifically take this reading during peak load.
    Take the reading of your outdoor/ambient air, if you have no digital psychrometer you can use a sling psychrometer with wetted wick cloth on the other sensing bulb of one thermometer.
    The temp measured by the thermometer with wetted wick cloth is the wet bulb temperature and the temperature measured by the other thermometer without the wetted wick cloth is the dry bulb temperature.

    Plot the measured properties in the psychrometric chart to determine the indoor/outdoor humidity.


    If you have Digital psychrometer, well and good, read directly indoor and outdoor air properties.

    The measured air properties are enough to determine the moisture build up. This shall be useful in sizing the proposed solution below:

    Proposed solution:

    A dehumidifier (if your location is closed in a body of water, like rivers or coast) you really require one (dehumidifier) to allow moisture removal on indoor air.

    Sizing can be done only by a qualified HVAC consultant. Since, psychrometic properties of air are plot on the psychrometric chart.

    If you understand what is happening to the building then you can do it your own. If not, hire a consultant to have the sizing done.

    If you adjust fan speed, you will require adjustable frequency drives and probably change your fan motor to at least a motor winding insulation suitable for Adjustable Speed Drive (ASD).

    Compare also initial costs from having a dehumidier or having the motor speed
    adjustable. which is more reliable and resolve the problem? that will be base
    on the assessment of the HVAC consultant.


    yp5

  5. #5
    Join Date
    Apr 2002
    Posts
    11,808
    Calculate the load first, find out how much is humidity, how much is temperature control so you know what you are really up against.

    People are a little active when they bowl, could have a bit of humidity generated inside, in addition to the moisture in the ventilation air.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

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