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Thread: Sizing

  1. #1
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    Feb 2019
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    Sizing

    First off I am a new member.
    I have 12.5 ton unit supply a commercial building that was wide open. The tenants have now decided to try an lease it out and need ducting through out. The total square footage of the building is 3400' with 12 ceilings that are now going to be 8' ceilings through out with ceiling tile. I am trying to distribute according to room size but am running into an extra 1500cfm. How should I approach this?

  2. #2
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    You need to size by room load not size. You can have 2 rooms both 1000 sq ft and because of a variety of conditions one can take twice as much air as the other, or they may both be the same.

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  4. #3
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    May 2014
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    If you are distributing to room size, then you will never have anything left over.


    Quote Originally Posted by Bringtheheat View Post
    First off I am a new member.
    I have 12.5 ton unit supply a commercial building that was wide open. The tenants have now decided to try an lease it out and need ducting through out. The total square footage of the building is 3400' with 12 ceilings that are now going to be 8' ceilings through out with ceiling tile. I am trying to distribute according to room size but am running into an extra 1500cfm. How should I approach this?
    [Could this be another PSE trap?]
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

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  6. #4
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    ~ Waves at PSE ~

    Sent from my SM-G965W using Tapatalk

  7. #5
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    Nov 2008
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    Lol, definitely not PSE.

    Sent from my SM-G965U using Tapatalk

  8. #6
    Join Date
    May 2014
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    How so? Did he get incarcerated?
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

  9. #7
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    Nov 2008
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    Long Island NY
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    I speak with him time to time. Plus the OP gave too much info, whereas PSE doesn't.

    Sent from my SM-G965U using Tapatalk

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  11. #8
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    Feb 2019
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    Thread Starter
    I would say most the rooms are the same except for the one the contains the windows and another that has an exterior wall.

  12. #9
    Join Date
    Mar 2013
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    Billington Heights, NY
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    push all the extra into those rooms. it's the hack way. it'll be fine.

  13. #10
    Join Date
    Jan 2010
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    And what is the return air plan ?

  14. #11
    Join Date
    Jan 2004
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    Quote Originally Posted by Bringtheheat View Post
    First off I am a new member.
    I have 12.5 ton unit supply a commercial building that was wide open. The tenants have now decided to try an lease it out and need ducting through out. The total square footage of the building is 3400' with 12 ceilings that are now going to be 8' ceilings through out with ceiling tile. I am trying to distribute according to room size but am running into an extra 1500cfm. How should I approach this?
    Manual N.

    I think your forgetting to allow for the number of people, fresh air, and lighting heat gain.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

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