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Thread: Portable AC

  1. #1
    Join Date
    May 2008

    Default Portable AC

    We live in New England and have a comtemporary cape. It can get quite warm and humid in the summer, but it doesn't last long.
    We are looking to add one or two air conditioners. Our problem is that we have cantilevered windows which makes it hard to use a window air conditioner.
    The portables look nice. Our lower level living area is about 630 sq feet with a cathedral ceilng in the livingroom. We may try to adapt a window to accomodate a window unit. Would 1200 BTU's be enough?
    Our bedroom upstairs is about 192 sq feet.
    We are looking at an 8000 BTU portable unit.
    We would appreciate any suggestions. Thanks

  2. #2
    Join Date
    Aug 2007

    Default Re: Portable AC


    I have my doubts that a portable will meet to your satisfaction---they are designed to cool a small area.

    If you can have the cantilever mechanism & glass removed from the designated areas, a window unit in both cases would do a better job of cooling both areas.

    Ordinarily, AC units are roughly sized by assigning 20 btu of cooling per square foot---thus 630 X 20 = 12,600 btu/hr and for the smaller unit 192 sq.ft. X 20 = 4000 btu/hr.

    Since you have cathedral ceilings in the living room, you would have to do a heat gain calculation to determine the size of the LR unit--it may be best to get some estimates from an AC contractor (Yellow Pages--"Air Conditioner Contractors") for installation options--it makes no sense to simply buy something at a store only to have it not work out for you, or be the wrong size.

    If there are other unusual factors present in the area to be cooled, such as ceilings over 8-9', a lot of glass letting in sun radiation (particularly from south or west-facing walls), complete lack of insulation in exterior walls & attic, etc., these sizing calcs wouldn't apply & you would also have to do a heat gain calculation.

    For a more accurate calculation of needed capacity, Google "sizing a window AC" or "heat gain calculation".

    The small unit can perhaps be plugged into an existing electrical receptacle if it has sufficient capacity in a 15 amp circuit.

    The larger unit would have to be wired with its own line to the main electric panel with a 20 amp fuse/circuit breaker---even better would be a unit using 220v with its own line to the panel--this would save electricity over a 120V unit.

    Another option would be a "thru the wall AC" where an 18" X 30" hole would be cut high up on a wall for the installation.

    There are also mini-split AC's that have the condenser & compressor outside that may be appropriate, but they cost closer to $4k installed--but this option would eliminate any window modifications or large holes in the walls.

    The July issue of Consumer Reports has a good review of window AC's of different sizes---also enter "room air conditioner" in the epinions search box to get a review of numerous units at that site.

    Consumer Reports is available at local libraries if it's not on the newstand.

    Choose an AC that has a high EER (energy efficiency rating) of over 10 to save electricity, one that cools well & is quiet in operation.

    Last edited by JacktheShack; 06-19-2008 at 06:30 PM.

  3. #3
    Join Date
    Jun 2012

    Default Re: Portable AC

    yes 1200 BTU's is enough for 630 sq with a cathedral ceiling in the living room.

  4. #4
    Join Date
    May 2011

    Default Re: Portable AC

    I assume you mean 12000. That should be plenty. In your climate, 9000 might be adequate depending on how many windows you have and the amount of shade.
    1925 Two-Story Stucco Beaux Arts Neoclassical

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