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  1. #14
    Join Date
    Sep 2002
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    Do you have the ability to increase the blower speed / CFM across the indoor coil?

    Wait a minute! Did you replace all the 2.5 ton sized old ductwork? If not; you are never going to get the proper airflow.

    For that matter: exactly how do you know that you have 1400 CFM now?

    BTW: What kind of program was that for the heat gain? It seems odd that it would indicate the need for 6.5 tons but recommend 4 tons.

    PHM
    ------------




    Quote Originally Posted by Skyhawks View Post
    The calculator I used showed a cooling load of 65K BTUs at 95°F outside, but recommended a 4 ton unit. The house originally had a 2.5 ton, but it never kept up at all.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  2. #15
    Join Date
    Jan 2004
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    Quote Originally Posted by Skyhawks View Post
    The calculator I used showed a cooling load of 65K BTUs at 95°F outside, but recommended a 4 ton unit. The house originally had a 2.5 ton, but it never kept up at all.
    How much above set temp did the house get with the 2.5 ton A/C.
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  3. #16
    Join Date
    Nov 2018
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    Thread Starter
    Quote Originally Posted by Poodle Head Mikey View Post
    Do you have the ability to increase the blower speed / CFM across the indoor coil?

    Wait a minute! Did you replace all the 2.5 ton sized old ductwork? If not; you are never going to get the proper airflow.

    For that matter: exactly how do you know that you have 1400 CFM now?

    BTW: What kind of program was that for the heat gain? It seems odd that it would indicate the need for 6.5 tons but recommend 4 tons.

    PHM
    ------------
    I didn't change the ductwork, but it was oversized to begin with. I'm measuring the 1400 CFM by converting DeltaT over an electric plenum heater. I'm sure I can bump it up to 1600 by increasing the return air a bit. I just didn't think it was important, because the return line is already running at just over room temperature, so I figured there wasn't much additional heat to transfer.

    The calculator computed 65K BTUs, but that was at 95 degrees outside. I'm guessing the 4.0 ton recommendation has something to do with my location (we rarely get up to 95 degrees).

  4. #17
    Join Date
    Nov 2018
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    Thread Starter
    Quote Originally Posted by beenthere View Post
    How much above set temp did the house get with the 2.5 ton A/C.
    It would get up to 80 in the house on 85 degree days, then cool to 70 by morning just in time to start warming again. It pretty much ran 24/7 all summer long.

  5. #18
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    Jan 2004
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    Quote Originally Posted by Skyhawks View Post
    It would get up to 80 in the house on 85 degree days, then cool to 70 by morning just in time to start warming again. It pretty much ran 24/7 all summer long.
    What size is the house? Sounds like its massive.
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