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  1. #1

    Dehumidifier Placement

    We are purchasing a 70 pint portable dehumidifier for our home. We keep our thermostat at about 82-84 and the humidity level typically stays between 50% and 60%, and even when though temperature feels comfortable you get that sticky feeling anytime you are moving around. We are hoping that lowering the humidity will make our home more comfortable with out having to lower the temp on the thermostat.

    We were considering different locations to place the dehumidifier for the maximum benefit throughout our home. One location that seems particularly attractive, is inside the wall cavity where the HVAC intake is. It is a large wall cavity with intake vents on both sides (one facing the front foyer and the other into the main hallway. There are two large intake ducts in the floor of this space, but plenty of empty floor space to one side. It would be easy to get electrical into this space as well as a drain hose for continuous drainage.

    I was wondering if it would be a good idea be dehumidifying the air immediately before it goes to the a/c for cooling or would this cause some sort of problem in the cooling or dehumidification processes.

  2. #2
    Join Date
    Jun 2001
    Location
    Oklahoma City
    Posts
    2,591
    I can't see using a dehumidifier with a set point higher than 78. I'd compare the amount of power it would cost to lower the thermostat to 78 or 80 vs. running the dehumidifier. If that's not enough, open the blinds/shades causing the A/C to cycle and dehumidify. Once you have exhausted those 2, then go for the dehumidifier...

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    5,303
    Quote Originally Posted by mseda View Post
    We are purchasing a 70 pint portable dehumidifier for our home. We keep our thermostat at about 82-84 and the humidity level typically stays between 50% and 60%, and even when though temperature feels comfortable you get that sticky feeling anytime you are moving around. We are hoping that lowering the humidity will make our home more comfortable with out having to lower the temp on the thermostat.

    We were considering different locations to place the dehumidifier for the maximum benefit throughout our home. One location that seems particularly attractive, is inside the wall cavity where the HVAC intake is. It is a large wall cavity with intake vents on both sides (one facing the front foyer and the other into the main hallway. There are two large intake ducts in the floor of this space, but plenty of empty floor space to one side. It would be easy to get electrical into this space as well as a drain hose for continuous drainage.

    I was wondering if it would be a good idea be dehumidifying the air immediately before it goes to the a/c for cooling or would this cause some sort of problem in the cooling or dehumidification processes.
    Tricky to locate the dehu in a spot that the dry air from the dehu circulates throughout the home. It should be an open spot in the home that the noise is not offensive. Putting it in the return require the a/c to circulate the dry air as opposed to natural circulation through open space.
    Dehus are excellent to maintain low humidity at any temperature. When a home is unoccupied, the dehu will provide <50%RH for much less electricity than an a/c.
    When there is cooling load, make sure that your a/c has a cooling coil temp that is 25-30^F below your space temperature to max the moisture remove while it is operating. Avoid fan "on" mode when a/c is short cycling. But with a/c short cycling, the dehumidifier will get you the <50%RH that will make you comfortable. Periodicly check your dehu to comfirm that is is removing the moisture is accordance with its specs. After you are through your first experience with a free standing dehu conside the more efficient high efficiency dehus like Ultra-Aire and Santa Fe. These can be ducted from out of the way locations to circulate throughout the home. And then the ultimate option is to add a small amount of fresh air to pruge indoor pollutants and renew oxygen. And maintain <50%RH.
    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
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,050
    You either have a lot of air leaks in your home, an oversized AC unit (far, far too common) or both. that's really high humidity for thsoe tmepratures... really high.

    It's pointless and inefficient to run a dehumidifier until the pace thats damp is already cooled to at least 75F. You'd be better off with a small portable window AC unit with long run times that will remove a lot of moisture than a dehumidifier.

    Actually many small protable AC units also function as dehumidifiers too.

    Consider the economics and comfort. You'll spend $100-$200 for a dehumidifer. It's could tke 2-3 years to recover that. Meanwhile you're uncomfortabel.

    You have a LONG was to go to get comfortable at 82F. You need RH down to close to 30%... or a dewpoint of about 45-50F to be reasonably comfortable at those temepratures.

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