Alternative Cooling

Discussion in 'HVAC Heating & Cooling' started by RRW, Jul 17, 2007.

  1. RRW

    RRW New Member

    Jul 15, 2005
    Anyone have experience with the Mitsubishi through the wall units or with the portable cool/heat units that breathe through a window?
  2. geniescience

    geniescience Homeowner

    Nov 27, 2005
    humid summers hot, humid winters cold
    are you referring to "split" units? I have seen a lot of them. The noise is concentrated more outside than with window air conditioners. I don't see why they should cost so much more than window units.

    as for the portable units tha tyou can roll from one room to the next, i have heard often that they are like toys.

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  4. TangoBob

    TangoBob New Member

    Jul 18, 2007
    portable AC

    I installed a portable AC unit for a customer and it leaked on her hardwood floor. Fortunately it was discovered right away and no damage. I do not understand what is supposed to happen with the condensate. I was told the heat produced by the condenser is supposed to evaporate the condensate. I don't trust that. She had me take it out.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    I've seen some portable a/c units that have a tank (sort of like a dehumidifier) and some that have a built-in pump that I think might be more reliable. I bought a Whirlpool unit for my mother that had a tank, and I bought a low-profile condensate pump to move it outside. I got it last year as a floor model for $99 on a $550 unit. Seems to work fine. If the humidity is very high, unless it is being pumped outside, I think any unit might be subject to problems if it relied on evaporation of the condensate to evacuate it in the air stream.
  6. Furd

    Furd Engineer

    Jul 3, 2007
    Retired energy systems engineer
    Wet side of Washington State
    I worked in a small office that had a Mitsubishi Mr. Slim mini-split A/C unit. It was oversized but it worked quite well. As long as the lowest fan speed was selected the noise was insignificant.

    I own a portable A/C unit. Mine is a dual-duct model and I would advise not buying a single-duct model. The single-duct models use room air to cool the condenser and then exhaust that out the single duct. What this means is that you WILL be drawing in untreated outside air somewhere. The dual-duct models use outside air to cool the condenser and then exhaust this outside with no room air interchange.

    Most dual-duct models also use a pump to move condensate over the condenser coil which both aids in cooling the condenser and evaporates the condensate which is then removed with the exhausted air. This works amazingly well and my condensate drain does not overfill even under high humidity conditions.

    Due to some abnormal weather this last week my inside humidity rose to about 80%. I ran this unit for most of yesterday and brought this inside humidity level down to 60% without any overfilling of of the condensate tank. That's not too shabby performance.

    Portable A/C units will be louder than a window unit because of an additional fan, the condensate pump and the compressor are all inside the room. The ducts are not insulated and they will radiate some of the heat back into the room. For these reasons a portable of any given size will not perform as well as a window unit of similar size. The window (or patio door) adapter for the ducts will also not fit as well as a properly installed window unit and there will be more air leaks.

    Using insulated flexible ducts will improve the operation of a portable A/C.
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