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  1. #1
    Join Date
    Aug 2011
    Location
    Central Arkansas
    Posts
    1

    New System suggestions

    Hello all, I have received a few estimates and the size of system seems to vary per contractor.

    I have a single story, on a slab, all brick, just under 1500sq ft house that needs a new system. Current system is 17yrs old and there is a refrigerant leak. It is in central AR where is has been up to 118* this summer but normally high 90's and low 100's and it gets humid here.

    What size system would you suggest?

    Is there a recommended brand or one to stay away from?


    Thank you

  2. #2
    There must be thousands of threads on this all ready. All of the replies go something like this:

    Choose your contractor on expertise not equipment brand.
    Throw out all bids from contractors who do not do an energy evaluation and or load calc.
    Cheaper is not necessarily better.

    Do a site search you'll find the answers you are looking for.

  3. #3
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,422
    Recommended practice would be to have a manual J heat load done on your home. If it's low on insulation, it is far cheaper to fix this than over-cool to overcome the heat gain. Have the home checked over by a reputable HVAC company, and see their figures on the manual J computations. Start there because you'll find most will just put in what you have and then you'll get what you've gotten in the past. Doesn't mean the old unit sizing is correct, but most will take the easy way out!!

  4. #4
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,881

    Do First Things First...

    Far too many factors in these equations to guess sizing from here.

    At 2.5%; Little Rock AK, summer design is: 96 dry bulb; 77 wet bulb, around 43% RH.
    111.54 grains of moisture per/lb air; better reduce air infiltration.

    A Home Energy Efficiency Audit would be called for, after retro-work do a Manual J for equipment sizing. A manual D duct design is also an excellent idea toward achieving optimal energy efficiency performance.

    There is a proper sequence to follow before you decide on the H-VAC contractor & equipment...
    Last edited by udarrell; 08-30-2011 at 01:44 PM. Reason: Little Rock AK.

  5. #5
    Join Date
    Jun 2009
    Location
    Albuquerque NM
    Posts
    2,484
    1. Because of how contractors like to size, it's very likely that the larger sizes proposed would be oversized for your house.
    2. You're probably going to be in the 2 to 3 ton range (see #3 below).
    3. You need a load calculation done.
    4. Oversizing results in poor humidity removal and decreased comfort (see #1).

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