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Thread: Plenum question

  1. #1
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    Plenum question

    Would ducts at the end of a plenum (on sides) have a tendency to pull more air? because they are at the end?

  2. #2
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    Yes. Path of least resistance. Are we talking about a plenum or a trunk (rectangular) duct? Balancing will take care of this problem

  3. #3
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    no just a plenum with traditional round metal ducts attached.

    I assume that the premium way to distribute the air would be a sophisticated trunk system, or is this over kill for a residential system?

  4. #4
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    Quote Originally Posted by stardotstar View Post
    no just a plenum with traditional round metal ducts attached.

    I assume that the premium way to distribute the air would be a sophisticated trunk system, or is this over kill for a residential system?
    Maybe we are talking about 2 different things. A plenum to me is the square duct rising up from the furnace/AH. The duct that runs horizontally acroos the basement or attic is what I call the trunk.

  5. #5
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    Probably my bad, talking about the supply side after the furnace where the air is distributed to duct lines?

  6. #6
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    Quote Originally Posted by stardotstar View Post
    Probably my bad, talking about the supply side after the furnace where the air is distributed to duct lines?
    You have an extremely basic form of a distribution system.

    You have a box on top of the furnace, and a bunch of round pipes attach to it, yes?

    That works well for certain applications.

    In a traditional residential home, you would find the box on top of the furnace (the plenum). Then square, 8 x whatever ductwork. Then from that square duct work, comes the round pipe.

    This is a good duct setup.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  7. #7
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    Horizontal system in attic, yes.

  8. #8
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    Quote Originally Posted by stardotstar View Post
    Horizontal system in attic, yes.
    How big is attic space?
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  9. #9
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    The take offs near the end will have better airflow

    If the extended duct (same size) doesn't leak then the airflow will be better because as the air is removed, the velocity in the trunk is reduced and the air has an easier time making that 90 degree turn at the take off.

    look at the take off fitting values close to the begining and after the 2nd, 3rd of more hits with no size change
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

  10. #10
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    Quote Originally Posted by hvacvegas View Post
    How big is attic space?
    about 1700 square feet<

  11. #11
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    Sounds like long flex runs.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  12. #12
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    The current duct work is metal and the longest run to the back bedroom with the lowest volume is about 30 feet.

  13. #13
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    star dot star

    Is that the old CPM86 *.* reference?
    You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!

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