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  1. #1
    Join Date
    May 2019
    Location
    Detroit, MI
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    8
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    Hanging Spiral Duct

    I have Sammy's with 3/8" threaded rod dropped from the joists every 8' to hang some 12" spiral. How do you guys go about attaching threaded rod to your duct. I originally wanted to use steel wire, but the builder decided to drop the ceiling where my run is so now I only have 9' (might have to resize now too ... ). I know a lot of people hang their ducts directly from the rod, but how do they secure it? Do you just use a locknut? I'm worried it'll eventually loosen from vibrations. Maybe I'm overthinking it. I do think it'd look better than the 16 gauge 2" double/single-rod hangers, and it'd buy me a little space.

    Oh yeah ... first post

  2. #2
    Join Date
    Dec 2009
    Location
    maroon lazyboy
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    2,664
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    You could wrap it with a strip of heavy gauge sheet metal, hole in each end goes on the threaded rod, with nut and fender washer above and below.

  3. #3
    Join Date
    Dec 2009
    Location
    maroon lazyboy
    Posts
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    Welcome to the site

  4. #4
    Join Date
    Apr 2007
    Location
    Tucson, Arizona
    Posts
    1,280
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    Ive used cables, single sling or both sides. I have a chart somewhere that lists sizes and weights the cable can support. Also used metal strapping, but for my personal shop I drilled a hole both top and bottom and nut and washer underneath. Ive used the same method on jobs that had limited height.

    There are two ways to do things, Right and Again.

  5. #5
    Join Date
    May 2019
    Location
    Detroit, MI
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    8
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    Thread Starter
    Thanks guys. I think I'll pop it through the bottom and hit the threads with some blue Loctite to make sure it doesn't work itself loose. I'll throw a 1" fender washer on it for good measure. The load shouldn't be more than 50 lbs. for each support so that should be pretty solid. The strip of sheet metal would be nice, but these people are really picky and I don't think they'll go for it. We'll see what the building inspector says Thursday.

  6. #6
    Join Date
    Apr 2007
    Location
    Tucson, Arizona
    Posts
    1,280
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    I would spend too much time with loctite or lock nuts, maybe double nut the bottom. Mine has been hanging for 12+ years TONS of vibration from high HP engines, air compressor, and Im near the Air Force base (some of these planes shake the entire house). None of mine have fallen off or loosened anything noticeable.
    There are two ways to do things, Right and Again.

  7. #7
    Join Date
    Mar 2015
    Location
    Medford, N.Y.
    Posts
    6,108
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    Check out the Sheet Metal Connectors,Inc. catalog, pg.17/18 or so.

  8. #8
    Join Date
    Mar 2013
    Location
    Treasure coast, FL
    Posts
    7,910
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    I can't imagine running the threaded rod through the duct is a kosher practice for a professional installation.

    Don't they make similar hangars to what plumbers use? Where the threaded rod goes into a circular sheet metal strap type apparatus?

    Sent from my Moto Z (2) using Tapatalk

  9. Likes Zamoramax liked this post
  10. #9
    Join Date
    Jul 2018
    Location
    Wisconsin
    Posts
    1,100
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    Forget the rod. Use cable, faster, easier and cleaner looking

    Sent from my SM-G960U using Tapatalk

  11. Likes lions_lair liked this post
  12. #10
    Join Date
    Jul 2018
    Location
    Wisconsin
    Posts
    1,100
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    .

    Sent from my SM-G960U using Tapatalk

  13. #11
    Join Date
    May 2019
    Location
    Detroit, MI
    Posts
    8
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    Thread Starter
    I usually use cable, but I dont have clearance for this install. I was originally thinking just punch it through the top so the rod isnt exposed underneath, but itd still be able to sway. For plumbing I typically use clevis or Milford hangers, depending on the size of the pipe. Ill probably just go with the clevis hangers and switch to saddle diffusers with scoops to make up for the drop ... I was trying to avoid a change order, but Im not really excited about dumping another $800 in material into the job either 😐

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