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  1. #1
    Join Date
    Mar 2013
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    72

    Balancing/improving performance of commercial duct system

    Hey all, the names jason and am new to the site and will be graduating this spring from tech school. Trying to get the post count up so I can apply for pro membership so here is my first question. I work at a large church and in the bookstore of the church the duct system is very noisy, what's are some effective or practical ways to dampen some of the noise? Off the main branch there are 6 supply branchs(flex) that are fed into the room. When I initially checked all six dampers on the supplies, they were all pretty much in the all the way closed position,opened some up/ adjusted and noise came into room instead of just bring in the ceiling, so it magnified the problem. Any advice would be greatly appreciated. Thanks.

  2. #2
    Join Date
    Jul 2007
    Location
    Mount Airy, MD
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    7,278
    Thread relocated to Tech to Tech

  3. #3
    Join Date
    Aug 2012
    Posts
    2,326
    Sounds like a air balance problem, you may have too small of a return or not enough supply a tesp test would give you some insight.
    Trying not to be a Hack.

  4. #4
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    5,821
    Noise usually means too much air forced through too small a duct (high velocity) .

    So now you must figure out why so much air is trying to go through those noisy ducts.

    And if the bookstore needs that much or if there is another design problem that is causing high static in that section of the trunk line (assuming that it has one)

  5. #5
    Join Date
    Mar 2013
    Posts
    72
    Thanks for the info. It's a wild return btw, I am going to check the temperature rise between the supply and return and go from there. What is a tesp test btw, not sure what that's an acronym for???

  6. #6
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    5,821
    Just put in a long reply that got erased.

    TESP is total external static pressure or the sum of both supply and return individual statics or SP for short.

    The individual readings will show if one side is worse or both equally bad.

  7. #7
    Join Date
    Mar 2013
    Posts
    72
    Thanks again for the info!

  8. #8
    Join Date
    Jun 2004
    Location
    St Paul, minnesota
    Posts
    1,015
    Quote Originally Posted by Jason2013 View Post
    Hey all, the names jason and am new to the site and will be graduating this spring from tech school. Trying to get the post count up so I can apply for pro membership so here is my first question. I work at a large church and in the bookstore of the church the duct system is very noisy, what's are some effective or practical ways to dampen some of the noise? Off the main branch there are 6 supply branchs(flex) that are fed into the room. When I initially checked all six dampers on the supplies, they were all pretty much in the all the way closed position,opened some up/ adjusted and noise came into room instead of just bring in the ceiling, so it magnified the problem. Any advice would be greatly appreciated. Thanks.
    need more information. size of AHU or RTU in tons or CFM'S. size of trunk line, size of 6 flex lines, and size of the room. Are you sure it only feeds the bookstore? If you're not sure of tons or cfms then post make & model #

  9. #9
    Join Date
    Mar 2013
    Posts
    72
    No it feeds some offices as well. I find that info n post it when I go back there. Thanks.

  10. #10
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    925
    someone closed the dampers to help with the noise most likely..you have to identify the noise, is it loose duct, turning vanes, fan belts, High static pressure, Is the noise air volume? or a rattle, does the unit have outside air. But like superfittertech said need more information. is the bookstore the only area that hears this noise?

  11. #11
    Join Date
    Mar 2013
    Posts
    72
    I'll be back at work today, I'll gather as much info/specs as I can then. Thanks.

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