Results 1 to 6 of 6
  1. #1
    Join Date
    Aug 2004
    My parents want to upgrade the Heatpump and indoor unit, they claim that it runs constantly on hot days, it is a 23 year old house and the insulation isnt the greatest, I dont want to replace it with a reccomended size for the insulation issue, how much bigger of a unit may I step up to befoe short cycling occurs, I have also heard of swaping reccomended size units between indoor unit and out door unit The house is a bi level house approximately 2800 square feet 1500 up stairs and 700 down stairs with a single garage below the master bedroom (square footage listed did take out the garage space)

  2. #2
    Join Date
    Aug 2004
    your asking for someone to guess it doesn't work that way you need to have a pro. do a heat load calc on the house to determine the correct size unit

  3. #3
    Join Date
    Aug 2004
    What part of the world do you live in ? tall are ceilings ,how many windows ,to many variables to do over comp. But if this helps in TX we go off 400-450 sq ft per ton for those 115 degree days

    [Edited by e_giles on 08-26-2004 at 09:24 PM]

  4. #4
    Join Date
    Dec 2003
    "the insulation isnt the greatest"

    First and cheapest place to start. Then caulking and weatherstripping.

    A properly sized unit DOES run all the time on a very hot day. What does it do the rest of the time?
    "That's good enough..." usually isn't.

  5. #5
    Join Date
    May 2000
    Yes, running a lot is proper for AC/heat pump. You can do your own heat loss/gain calculation with HVAC-Calc

  6. #6
    Join Date
    Jun 2004
    4H: Hot, Humid Houston H.O.

    What size unit for a home

    Your question is just a little like asking "how big an engine does my truck need?". Like several others I would pony up $50 and get a copy of HVAC-CALC, and use it to do a load calculation. That's what I have done for my house and it gives me a certain amount of confidence what is the right size heating or AC unit.

    The program is easy to use, as promised. There is a whole thread about HVAC-CALC with generally high praise. There are other programs out there but I don't know of one as easy to use at this price.

    One thing I have learned, is inadequate AC performance by no means tells you the unit is "undersized". Most of the time it tells you there is a duct problem or other craftsmanship issue. Makes the problem thornier but different, maybe cheaper but definitely more work to solve.

    Once again, I cannot emphasize enough how important it is to get a load calculation done. If you really don't want a do-it-yourself program, then get a few HVAC companies to do a load calc as part of their bid, before you buy anything else. And keep your "baloney detector" working <g>!!!

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