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Community and Q&A

How much does a 90 degree angle plenum actually effect air flow?

Aston01 | Posted in Mechanicals on

I’ve seen them used due to space constraints, but I was wondering how much of an impact it actually has on airflow as opposed to something like a pair-of-pants style?

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  1. Expert Member
    Akos | | #1

    If it is big enough, the shape of the plenum doesn't matter much. You should still watch your fittings, those takeoffs on the picture add 35 feet, a better takeoff would only be 10 and take up very little extra space.

    I have done larger non pants style plenum on low static units (0.15 in w.g.) without issues. A V shaped flow splitter in the middle is still a good idea if you have takeoffs on both sides. I don't remember the exact pressure drop through the plenum but it was small enough to not worry about it. This was with proper takeoffs and V splitter.

  2. Aston01 | | #2

    That was just a picture I found on google, but now you have me curious...what is considered a good quality takeoff?

    1. Expert Member
      Akos | | #3

      See attached.

      1. Aston01 | | #4

        Ahhh so they have a smoothed transition at the throat instead of a right angle. Thanks for the clarification.

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