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  1. #1
    Join Date
    Jan 2017
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    Flex ducting or solid ducting

    Hi,
    my question is,
    Can I use flexible ducts in 4-story commercial building, throughout the drop-ceiling spaces????

    Thank you

  2. #2
    Join Date
    Mar 2013
    Location
    Billington Heights, NY
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    14,907
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    maybe, if the commercial code in your area allows it. check with the building department.
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

    Jtrammel - "Im going to sell hvac systems derp derp derp"
    BBeerme - "every time he opens his mouth, he reminds me of a cow without the fart bag."

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  4. #3
    Join Date
    Aug 2016
    Location
    San Diego, CA
    Posts
    78
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    Usually one uses hard duct to get close to the register, then flex for the rest of the run. Makes it easier to remove the register in the T grid.

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  6. #4
    Join Date
    Apr 2017
    Location
    Houston, Tx
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    529
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    if you can afford steel duct, then IMO buy steel duct. at least for your trunks.

    is this a plenum space btw? Im not sure, but-just like cabling, i think some flex duct jacketing is plenum space rated and some is not.

    Here in my office there are random contractors running cable and conduit through the drop ceilings all the time... new leasers are always looking for new can lights, new serurity systems etc.

    I have a hard time imagining that these contractors are particularly concerned about disturbing the duct work, nor do the building maintenance people check on the new work. i will say though... for what reason the trunk is RIGHT ontop of the drop ceiling for some reason, so maby this is less of an issue with the duct more out of the way.

    If this place had flex duct im pretty sure there would be constant damage from all of the molestation, but thats just my opinion.

  7. #5
    Join Date
    Mar 2015
    Location
    Tx
    Posts
    887
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    Quote Originally Posted by HVAC_Marc View Post
    maybe, if the commercial code in your area allows it. check with the building department.
    Also if Plan & Spec job, Engineer will have to approve the flex trunk lines. Get that in writing.

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  9. #6
    Join Date
    Dec 2013
    Location
    TN
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    52
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    It usually ranges from about 5'-7' varies from state to state for commercial..But it would not be uncommon to find some 10' + length runs if you open a few tiles up and pop your head in the ceiling..Very common in remodeled hospitals..Even know I hate using the terms "sometimes you have to do what you have to do" but it's inevitable eventually...I do take alot of pride in my work it is a art to me reason why I started this field..I went through a sheet metal apprenticeship before I went through school to become a HVAC tech...So I tend to get picky about my ductwork...

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  11. #7
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    20,052
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    In commercial we are limited to 6 of flex per branch line. We run hard pipe in 5 lengths until we get close to the diffuser then flex from there.

  12. Likes DavidDeBord liked this post

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