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Thread: A/C retrofiting

  1. #1
    Join Date
    Jun 2006
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    We bought a house without A/C that is 12 years old. It's a two story with the basement half way in the side of a hill. Essentially, that makes the house a three story.

    We retrofitted the house with A/C - but the upstairs still doesn't get good A/c airflow - in fact, the heat doesn't work so well in the winter - so I think there might be something wrong with either the size of the ducting to the rooms or maybe the fact that there's only one air return upstairs.

    Does anyone out there have any ideas on how I might be able to improve the airflow upstairs? Any way to force air into the return with a fan of some sort, or do I need to think about major work and upsize the ducting to the rooms and add more returns?

    I'd appreciate any ideas.

  2. #2
    Join Date
    Feb 2006
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    Get a contractor...

    An AC system will be useful, if it is sized properly, matched properly, and fitted with the right ductwork. You have to call three contractors (or more) for price bidding.

    You have to specify these to them:

    1. Heat gain and loss calculations using Manual J, and

    2. Duct sizing using psychrometrics and Manual D.

    They will give you recommended sizes and brands for the AC.

    Check that they have done proper load calculation and duct sizing as per (1) and (2).

    They might provide you with the top of the line AC with highest efficiency. But, that might not be economical for you in the long run.

    Ask them if they have other, lower (slightly) efficiency ACs.

    Do a simple total ownership cost calculation, and choose the right one for you . Here's a brief guide:

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