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  1. #1

    Question Block load calculation question

    I'm using the Manual J "MJ8ae v1.08" spreadsheet to calculate the block load of a house.

    Is it possible to perform a block load without entering all room loads, i.e. just enter data about the house envelope, and any areas within, that are not conditioned?

  2. #2
    Join Date
    Jun 2004
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    4H: Hot, Humid Houston H.O.
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    Quote Originally Posted by unclebingo View Post
    I'm using the Manual J "MJ8ae v1.08" spreadsheet to calculate the block load of a house.

    Is it possible to perform a block load without entering all room loads, i.e. just enter data about the house envelope, and any areas within, that are not conditioned?
    I have done that using Hvac-Calc. Interesting to revisit that project later with a room-by-room version, and see some noise within the model. That was Manual J V7 so you may see a different and better model.

    Hope this helps -- Pstu

  3. #3
    So, to clarify. You used HVACCalc to perform a block load of the house envelope only, rather than performing a room by room load and have HVACCalc total up for a block load?

    Presumably the room by room approach is more accurate but more time consuming?

    Did you create any partition walls inside the house envelope between conditioned and nonconditioned spaces?

  4. #4
    Join Date
    Jan 2004
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    Lancaster PA
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    Block loads are good for sysing equipment for a bid.

    But, won't give you air flow for rooms, to size youor duct system.
    Contractor locator map

    How-to-apply-for-Professional

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

  5. #5
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
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    3,304
    Quote Originally Posted by unclebingo View Post
    So, to clarify. You used HVACCalc to perform a block load of the house envelope only, rather than performing a room by room load and have HVACCalc total up for a block load?

    Presumably the room by room approach is more accurate but more time consuming?

    Did you create any partition walls inside the house envelope between conditioned and nonconditioned spaces?
    Yes, pretty much as you describe. Would it help if I emailed you a copy of the report for you to see what was calculated? If so look in my profile for an email address.

    Did not create any partition walls, if a space was inside the conditioned envelope it was conditioned space (rooms like interior closets have very low heat gain and loss). Would you like to elaborate on where you might use a partition wall?

    I may be the most talkative on this thread but by all means study all the other replies as they usually are more knowledgeable.

    Hope this helps -- Pstu

  6. #6
    Thanks Pstu
    I would describe a partition wall to separate a conditioned utility room or den in the basement with a garage that sits within the house envelope. In that case there might also be a partition floor that sits atop of the garage space.

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