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Thread: hvac sizing

  1. #1
    Join Date
    Sep 2007
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    20

    Hmm hvac sizing

    I know manual J is what most people are going to say. I am just curious if a new home in KY with cellulose in walls and ceiling at r50 and it has 1988 square feet in it could get by with a 2.5 ton system. one trey ceiling and on 18x18 cathedral ceiling. An opinion>>>>

    Thanks

  2. #2
    Join Date
    Apr 2008
    Posts
    31
    I live in North Carolina, my house is a 2235 square feet. I have a 2.5 ton ac unit in my house. Mine does great. It is a track house so everything far as the insulation in house is at bear minimum.

  3. #3
    Join Date
    Jun 2001
    Location
    Louisville, KY
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    12,189
    Quote Originally Posted by newblade View Post
    I know manual J is what most people are going to say. I am just curious if a new home in KY with cellulose in walls and ceiling at r50 and it has 1988 square feet in it could get by with a 2.5 ton system. one trey ceiling and on 18x18 cathedral ceiling. An opinion>>>>

    Thanks
    Could be over; could be under; could be right.

    It all depends the direction and number of windows.

    I've seen a 2000 sf ranch take 5 tons because of huge SW glass exposure.

    I've seen a 2000 sf ranch take 2 tons.

    Only the a proper load calculation will tell.
    Perhaps you should have read the instructions before calling.

  4. #4
    Join Date
    Jan 2004
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    PA
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    You can guess, and waste thousands of dollars to be miserable.
    Or you can have the load calc done, and be comfortable.

    In another thread, there is a member with 4000 sq ft home, he has a 2 ton A/C. It might even be over sized a little.
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  5. #5
    Join Date
    Dec 2006
    Location
    Middle Tennessee
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    11,347

    *

    Quote Originally Posted by beenthere View Post
    there is a member with 4000 sq ft home, he has a 2 ton A/C. It might even be over sized a little.





    .

  6. #6
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    PA
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    Screen name paul42.
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    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    Jan 2007
    Location
    Minneapolis, MN
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    415
    Will anyone consider infiltration? Let's guess... it's tight.

  8. #8
    Join Date
    Sep 2007
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    20

    Confused

    Thanks for the replies. Does anyone know if there is an online manual j calculator that you don't have to download or an explanation of how to do it manually? Also anyone know the numbers for KY?

  9. #9
    Join Date
    Jun 2001
    Location
    Louisville, KY
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    Why isn't your contractor doing a load calculation?
    Perhaps you should have read the instructions before calling.

  10. #10
    Join Date
    Jan 2004
    Location
    PA
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    No.
    But it doesn't take long to download teh hvac calc program.
    Plus you can then use it to see if adding first would decrease the size of the unit you need.
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  11. #11
    Join Date
    Mar 2008
    Location
    Houston, Texas
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    352
    Is there anyone here who is a master of percision guesswork? I'm a pretty good guesser, but haven't recieved my MGL yet.

  12. #12
    Join Date
    Sep 2007
    Posts
    20

    Wink

    Sometimes you need to do things yourself so that you know they are done correctly.

  13. #13
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,189
    Who's your contractor? I might be able to provide some insight.

    Don't post it. Shoot me an email.
    Perhaps you should have read the instructions before calling.

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