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  1. #1
    Join Date
    Dec 2007
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    Question Curious about Central A/C & Heat & Dehumidifying

    I have a question about central air conditioners/heaters and dehumidification. I live in an apartment right now, but in the future would like to have a house with central air. Do any central air units include dehumidifiers where you can just set the level of humidity you want and walk away? Or do you have to purchase a separate dehumidifier? Can a separate whole house dehumidifier be hooked up with central air? I would like to be able to control the humidity level without very much noise and without having to empty buckets or drain into an interior floor drain.

    Thanks for any information!

  2. #2
    Join Date
    Aug 2007
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    The Great White North
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    Default Re: Curious about Central A/C & Heat & Dehumidifying

    Central air conditioners are basically a large dehumidifier while running.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    Dec 2007
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    Default Re: Curious about Central A/C & Heat & Dehumidifying

    Thanks for your response.

    I'm also wondering about times when I wouldn't have to run the AC or heater but when it is too humid...

  4. #4
    Join Date
    Jul 2009
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    Northeast
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    Default Re: Curious about Central A/C & Heat & Dehumidifying

    They make whats called a bypass humidifier that has the air moved through a water panel by the Blower motor in you furnace and a power humidifier that has a fan installed in it that draws the air through a water panel. These two have water supplied via a line that's installed to the home water supply and a drain that goes to a condensate pump. They have a summer winter damper so it can be closed during the summer along with the 1/4 inch saddle valve. It's not a bad idea to have a PM agreement with your Heat and A/C System and this way the your HVAC Guy can change the water panel when it's needed. Most also have a humidistat which works basically the same way as a thermostat only it regulates humidity instead of heat. These are usually installed on the supply plenum or main trunk but I have seen them on the return plenum.
    An A/C System is a big Dehumidifier, it takes the warm humid air back through the return wrings it out, cools it down and sends it back through the supplies.
    Your top of the line A/C Systems such as Carrier/Bryant will run at a low RPM until the humidity is out of the house and then ramp up to high RPM for the cooling.
    Humidifier brands include AprilAire, Honeywell and, GeneralAire to name a few.
    I hope this was helpful, Good Luck!!!
    Last edited by Sten; 01-20-2010 at 11:01 PM. Reason: sp.

  5. #5
    Join Date
    Jan 2010
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    163

    Default Re: Curious about Central A/C & Heat & Dehumidifying

    There will likely be very few times when the humidity is high enough to be uncomfortable while at the same time you would not need to run either the AC or the furnace.

    Operating either one will reduce the house's relative humidity.

    When the time comes that you actually have an HVAC system installed, do not make the mistake of installing an over-sized AC unit. This is perhaps counter-intuitive, but bigger is not better with AC.

    If you install an over-sized unit, say, a 3-ton unit where a 2-ton would work, the unit short-cycles. This results in the unit shutting off before it has had a chance to condense humidity out of the air. A properly-sized unit will run all thru the heat of the day on the hottest days of the year, and will actually use less power and give greater comfort than an over-sized unit.

    Hire an HVAC contractor who knows how to do an accurate load calculation for the house. HVAC systems should NEVER be sized by rule-of-thumb methods. (Like X-tons per XXX-square feet.)

  6. #6
    Join Date
    Jul 2009
    Location
    Northeast
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    661

    Default Re: Curious about Central A/C & Heat & Dehumidifying

    A properly sized unit also should not run all through the day, if this is happening the unit would be undersized. It should work the way your furnace does, gets the house to temp, then shuts off till it needs to get the house to temp again. The amount it runs also depends on your stat settings, the lower the setting the more it will run. I keep mine at 74 degrees and once the humidity is gone we are more than comfortable but that is more a personal preference. Good Luck!!!
    Last edited by Sten; 01-21-2010 at 08:30 PM.

  7. #7
    Join Date
    Dec 2007
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    Default Re: Curious about Central A/C & Heat & Dehumidifying

    Thanks for the very useful advice! It really is helpful.

  8. #8
    Join Date
    Dec 2007
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    17

    Default Re: Curious about Central A/C & Heat & Dehumidifying

    The reason I'm asking is because I had a bug problem with some bugs who like humidity. I have to keep the humidity lower than 43% in order to make sure I do not have a problem with them again. Also, I live in Southern California where heating isn't always necessary, but dehumidifying is in order to keep it as low as I want it. I'm not sure if I'll continue living in an environment where heat isn't as necessary in the winter, but even in more northern climates, there are times in the spring and fall when the temperature is pleasant enough, but it's too humid...

  9. #9
    Join Date
    Feb 2010
    Location
    Iowa, Quad-Cities area
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    129

    Default Re: Curious about Central A/C & Heat & Dehumidifying

    Quote Originally Posted by me1717 View Post
    The reason I'm asking is because I had a bug problem with some bugs who like humidity. I have to keep the humidity lower than 43% in order to make sure I do not have a problem with them again. Also, I live in Southern California where heating isn't always necessary, but dehumidifying is in order to keep it as low as I want it. I'm not sure if I'll continue living in an environment where heat isn't as necessary in the winter, but even in more northern climates, there are times in the spring and fall when the temperature is pleasant enough, but it's too humid...
    If humidity levels are too high (even with the A/C system running) you may want to install a seperate whole house
    de-humidifier.

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