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  1. #1
    Join Date
    Oct 2009
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    Mukwonago, WI
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    Fan-Powered VAV box?

    Still trying to figure this one out. Inline fan on the discharge of the "VAV box" blowing into it from the ceiling space. There are multiple of these setups.


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  2. #2
    Join Date
    Nov 2006
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    SE Wisconsin
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    Might be some sort of series fan powered box?

    Ken

  3. #3
    Join Date
    Apr 2016
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    Maryland
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    Is this an actual vav box commercially manufactured or something someone field built ?

  4. Likes Nuclrchiller liked this post
  5. #4
    Join Date
    Jul 2010
    Location
    Melbourne / Victoria / Australia
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    It's not ceiling space return air and the fan only runs in heating mode does it?

  6. #5
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
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    Quote Originally Posted by CHILLERSVCMAN View Post
    Is this an actual vav box commercially manufactured or something someone field built ?
    It does look like somebody modified a VAV box. Tried to give it a single stage of heat, using return air.

  7. #6
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
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    I agree with Nucirchiller. It looks like a pneumatically controlled VAV converted to electronic controls with a fan added for ceiling space heat recovery. If so the modification was probably a waste of money. With the fan off in the cooling mode I would check for leakage into the ceiling plenum.

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  9. #7
    Join Date
    Oct 2009
    Location
    Mukwonago, WI
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    Thread Starter
    The fan is into the ductwork, not the VAV box. The ceiling space is not used as a plenum, has transfers out to the lobby with a central return grill.

    The fans are disconnected and just dumps air into the ceiling space. Ceiling space is like 55, all boxes are like this. WTF hahaha

  10. #8
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
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    We realized the fans were in the duct. You didn't say they were disconnected. Bottom line it was a bad idea that instead of getting the desired results it made things worse.

  11. Likes Nuclrchiller liked this post
  12. #9
    Join Date
    Sep 2015
    Location
    Southern California
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    That's a wattsinhel model FPBS2020 common in several parts of the Country
    Here is the breakdown.
    Wattsinhel = What in the Hell
    Model. FPBS2020 = Fan Powered Bull Spit
    2020= see it clearly
    Across the Country= Hacks Everywhere

  13. Likes CHILLERSVCMAN, Nuclrchiller liked this post

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