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  1. #1
    Join Date
    Nov 2010
    Posts
    156

    No screws holding metal duct together?

    Regarding my new system install in progress.. the contractor isn't using any screws to hold the KD metal duct together, just VentureTape 1599B around the seams (no mastic either). I thought it was standard practice to at least put a screw into each connection to mechanically secure in case someone bumps into the duct work while doing other construction in the attic. Or is this the "new modern trend" to just use tape to hold it together? Basically my reason for posting this is to better understand how big of a deal to make this when I talk to my contractor next week, or if I should stay quiet about it and move on to other things.

  2. #2
    Join Date
    Jan 2009
    Location
    Fairfield county Connecticuit
    Posts
    778
    They use Pittsburgh locks, ears and drives tape to seal no need for screws on trunk need them on the ATD's

  3. #3
    Join Date
    Nov 2010
    Posts
    156
    Quote Originally Posted by Danimal535 View Post
    They use Pittsburgh locks, ears and drives tape to seal no need for screws on trunk need them on the ATD's
    The male KD connections are just the typical crimped KD ends that slide into the smooth end. I didn't see any Pittsburgh locks or ears or anything fancy like that on these ends. Just tape is holding it together. When they lifted it up to make a modification the whole thing seemed to flop around like the tape was flexing at the joints.

    I have a feeling the contractor might tell me that they're going to strap it to the ceiling joists instead over the top of the insulation. Is that an acceptable way to do it?

    p.s. I am paying $18,000+ for this system. I did not go with the lowest bidder, instead I went with the guy who "appeared" to be most meticulous with quality. So I want to get what I'm paying for..

  4. #4
    Join Date
    Jan 2009
    Location
    Fairfield county Connecticuit
    Posts
    778
    The KD should be in two pieces when the two pieces are put together with the Pittsburgh to become one duct. Then say on a rectangular duct at the end were another piece of duct meets the top and bottom usually the wider part has slips which the two ducks join, on the narrow part drives which lock it together and then are banged over the slips then tape to seal for any air leaks

  5. #5
    Join Date
    Jan 2009
    Location
    Fairfield county Connecticuit
    Posts
    778
    http://t2.gstatic.com/images?q=tbn:A...CF31W_SbuCp-JQ

    See joint on left that is a locking drive

  6. #6
    Join Date
    Nov 2010
    Posts
    156
    Quote Originally Posted by Danimal535 View Post
    http://t2.gstatic.com/images?q=tbn:A...CF31W_SbuCp-JQ

    See joint on left that is a locking drive
    Mine are all round KD duct with slip-together fittings (one crimped end, whatever that is called). No locking grooves, just the tightness of the rounds pushed inside each other + tape holding it together..

  7. #7
    Join Date
    Jan 2009
    Location
    Fairfield county Connecticuit
    Posts
    778
    I would have them screw round duct together no doubt and tape joints.
    KD is flat duct Knock down KD two pieces

  8. #8
    Join Date
    Sep 2002
    Location
    Northeast Ohio
    Posts
    4,842
    We tape first, then 3 screws per joint.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  9. #9
    Join Date
    Nov 2010
    Posts
    156
    Thanks guys. If this was your house, would you insist on the contractor taking apart the insulation and putting screws in there?

    I am worried the tape will come apart if my electrician or some attic worker accidentally kicks the duct when it is missing screws to hold is secure.

  10. #10
    Join Date
    Jul 2010
    Location
    georgia
    Posts
    562
    Can you snap some pics before they cover up their work? Could be useful later if needed.

    You may want to get a second company to come out and give the install a look over before making payment.

    Again, voice your concerns -- take notes and bring these issues up now or wait until they request payment. Also make sure it passes local inspection before payment.

  11. #11
    Join Date
    Sep 2010
    Location
    phoenix
    Posts
    73
    I was taught (35 years ago) that you put a minimum of 3 screws up to 12 inch ducts. And 5 screws in ducts 14 inches and above.... that was a rule of thumb back then....
    I know I would not want my ducts held together with just tape... but thats just me...

  12. #12
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    4,930
    Quote Originally Posted by ScorpionLeather View Post
    Mine are all round KD duct with slip-together fittings (one crimped end, whatever that is called). No locking grooves, just the tightness of the rounds pushed inside each other + tape holding it together..
    KD whos and whatsa?

    Is it rectangle or round? Souns like it's round.

    Rectangle duct, is s-lock and drives. Drives hold the pieces together.

    Round, is a raw edge, going overtop of a crimped end.

    If it's round, it needs screws,

    If it's square, it doesn't.

    You sure their not screwing it, and then taping? Thats how I run round pipe.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  13. #13
    Join Date
    Jan 2007
    Location
    N.E. Ok.
    Posts
    1,363
    Quote Originally Posted by rbelisle1 View Post
    I was taught (35 years ago) that you put a minimum of 3 screws up to 12 inch ducts. And 5 screws in ducts 14 inches and above.... that was a rule of thumb back then....
    I know I would not want my ducts held together with just tape... but thats just me...
    That's 1 rule of thumb you can bank on, it needs screws and would fail inspection around here.
    Bead of mastic on female end 3 screws on smaller pipe than mastic connection and seam of pipe and elbows.

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