How-To Connect Flex Duct to a Collar - The Duct Shop

In this video we show you the correct way to connect flexible duct to a round collar to ensure no air leaks into the attic. Once you've separated the inner (black) jacket from the insulation and outer jacket, slide the inner jacket over the collar, ensuring it slides over the entire piece. after completing that, secure with a zip tie and tighten with a panduit gun. Secure and seal the connection with flex fix tape. Unroll the insulation and outer jacket, then secure with a zip tie and flex fix tape as demonstrated.
The Duct Shop.com offers a full range of HVAC ductwork and accessories for your next job, check us out today!!!

[@PeerEnergyCorporation]

In a humid climate compressing duct insulation will make it sweat. Panduits can only be used on inner liner and the outer liner cannot be crushed or touching other ducts. This method might work in the northern zones but in Florida, the Mech cons

[@danejensen6064]

This is why some people have mold problems from people who don’t know how to correctly fit hvac equipment

[@jenko701]

Great video , there are a lot of ways to do this . I like to tape the inner liner first making sure that the tape is making contact with both the inner liner and the metal equally, then I put a strap around it , next I pull up the outer and insulation. I make what looks like a suction cup by folding the inner liner inside the insulation so no insulation is exposed , the put the last strap . It won’t ever leak and looks good .

[@audrybella6405]

Thank you for this clear and concise instructional video.

[@marvinosegueda157]

We put mastic at the collars first Then we tie and then tape and seal with mastic again

[@ronherkey148]

Thank you for setting that straight

[@tomfrantz]

Thank you. Great directions!!!

[@BD-bd8cs]

Any different method when connecting flex to an adjustable elbow? There is no neck ridge to protect the panduit (zip) to fall off the elbow.

[@hup4030]

Appreciate the instructions on how to build the ducts, but you didn't mention Mastic Sealant to make them air tight.

[@pauljewel6988]

Reading through the comments there are many many different ways to do this, I have been written up for not doing it the company way and have been berated for not doing it the Texan way. If you are a Sheetmetal worker check with your Forman to see the way the the company you are working for at the time does it. fair warning.

[@lv5960]

Thanks a lot !!!

[@ZimZam131]

Let's start by getting our terms right. The "inner liner" is called FLEX DUCT. All the material around the flex duct is the INSULATION. Next, you want to attach the flex duct to the boot, zip tie it so it doesn't pull off. Then apply mastic to seal the air in. You can substitute the mastic with HVAC tape if you can get a good seal around the boot, but the result generally is not as high performing. Pay attention here: DO NOT ZIP TIE THE INSULATION. All you're doing is crushing the insulation, destroying the R value, and a zip tie can't really grip insulation anyway. You can simply use aluminum HVAC tape to seal the insulation to the insulated part of the boot (register box). And you're done!

[@jstriker623]

Bringing a handheld mirror would help to know if the other side of the duct looks good.

[@tangamandapio9013]

Good

[@idanny76]

I have high static pressure on a new 3.5 ton heat pump. I know for sure the flex duct is the issue. I have two 12" coming out of the supply in opposite directions. I know I need an 18" for a 3.5 ton heat pump. I did a diagram layout of the duct in the attic. What would happen if I just replace the two 12" to 18"? Ignoring the downstairs, because everything is between the walls. The problem was even worse with an undersized return. The original and only return was a 24x18. The total static pressure on the unit was .9 W.C. I was able to drop the TESP to .66 by making the return 30x24. Since there is so much static pressure and the unit TESP is a .2 and I need an 18" for a 3.5 ton for 1400 CFM. How big does the supply plenum should be and what shape? Should the supply plenum split to 3 18" going out to each of the 3 distribution boxes? Do the other three distribution boxes also need to be larger? Looking at the triangle shaped supply plenum I have very little room up for a rectangle plenum. I think a 3 feet ductboard supply plenum should work. There is a foot from the Air handler to the ceiling and I think 2 feet from the attic floor to the roof. Now I am looking at two types of designs. Design #1 keeps the 18" ducts straight by having a single 18" coming out of the supply and then a distribution box splitting it to three 18". The sides would be coming out straight to the to side boxes and one going to the third box with a slight curve. Design #2 splits to three right at the supply plenum and goes to each box individually, but all three will have a slight curve. I will not be using any metal plenums..... it will be all flex duct and ductboard boxes, because of budget. I am not trying to make a perfect system, but trying to remove the restriction from the 12" undersized ducts installed and replacing the flex duct that was patched with mastic with new ones. Another question about the installation..... I have the flex duct running up and strapped to the roof for support. Since the supply plenum is low to the floor due to the roof..... Can the flex duct be run on the attic floor? Can you tell me which layout makes more sense and less restrictive? Thank you. Layouts: Current i.ibb.co/Ld9kmPM/Flex-Duct-Layout-and-Size.jpg Option #1 i.ibb.co/GHyS00g/2022-07-05-0002.jpg Option #2 i.ibb.co/PNN8mSB/2022-07-05-0001.jpg Air Handler Specs ibb.co/17VvF4B Video of attic kzbin.info/www/bejne/n3rReoFubtZrfbc

[@diaperdood1]

What size is the inlet on the register and the size of the flex duct?

[@jaimebonilla7750]

Butter the inside zip tie and zip tie the outside your done ✅

[@diaperdood1]

So am 8 inch flex duct would connect to an 8 inche duct register?

[@xmtowntyx]

Inner liner, then tape it, then ziltie then pull putter down and tape that to the duct

[@happypedro12]

ok so silly question: why do you need the panduit gun? Can I just use nylon zip ties and then just hand tighten them? Thanks

[@kentaltobelli1840]

It tightens much more than what you can achieve by hand to compress everything against the metal collar.

[@MenacingMoto321]

I have a register I am removing as we removed the wall it was connected to, how do I plug the existing duct work? Not really any need to cut it all off, but I want to just plug the flex duct.

[@vinnymac8127]

You shouldn't just plug the flex duct it's definitely not the right way to do it. Remove the entire piece of flex duct and the collar that's in the trunk duct. Cut a piece of sheetmetal that's at least two inches bigger than the hole each direction and screw it over the hole in the duct with sheetmetal screws. For example, if you have a 6" round hole in the duct, just cut your metal 8" by 8" so it overlaps an inch each direction and screw it. Then seal it completely with mastic and put a piece of insulation over it so it doesn't sweat. Tape the insulation on good and you're done.

[@yauck1]

Vinny Mac usually plenums have insulation inside so don’t forget to mend it too.

[@envieddesigns]

I have one vent in a room that I just know it’s not blowing properly all other vents in the house I can hear significantly air blowing but this one vent is not. I had a tech come out today because I felt some cold air leaking from where that vent connected to the air handler in the attic. They came out an put tape around it to seal it better but I’m still not satisfied. Now thinking that that duct may have a kink in it maybe where the strap is holding the duct to one of the beams in the attic. Could that cause less air flow and how would I check that. Should I drop the strap that’s holding that duct up?

[@skydemon02]

I have the same problem

[@rolandedrummer9723]

What are the local inspectors insist you take first on the collar. He will fail it for sure if you don't.

[@mohammedshamshuddin2298]

Hello

[@JillofAllTrades2]

No mastic?

[@MrUrbman]

Good thing your ballcap is protected by your safety glasses!

[@dmize6794]

Tape first then strap then insulation then strap again

[@kenk8215]

Good video. BTW it's pronounced "duct" not "duck".

[@jstriker623]

Ken K Quack Quack. It's duck! Aflack!

[@darwincarranza4698]

LOOKS LIKE NO INSULATION WAS GRAB BY THE ZIP-TIE AT ALL

[@joefleming3023]

Yep. That part of the duct will sweat heavy in a humid attic or interstitial space.

[@rickmcphee4206]

Shoddy work

[@SM-ok3sz]

To any viewers: if a flex duct tutorial doesn’t include mastic, they’re not doing it right and you should find another video

[@MrCoolrush]

sorry but you are wrong if you zip tie out side of the flex you kill the r value not sure what state you are in but in the state of florida that will not fly

[@hvacrookie6208]

Agreed. I did this sort of work in FL for a little bit. You have to be careful with your insulation down there. I am not sure whether the box is internally lined, but that should be insulated, as well (at least for FL). You also need to be careful not to create kinks in the flex. It should be able to extend straight up from your box/diffuser and not be angled in the way the final product was in this video. I can tell he works hard and takes pride in his work, but I think those small details will make a difference on a large project.

[@adamscan4u682]

I was wondering this same thing. Plus I noticed it made the edge of the insulation flare out and away from the takeoff

[@nym5635]

Ive had to change my ducts every year because in the winter months there are buckets of water in my ducts what can I do to remedy that ? 25 ft of duct is 124 dollars and it's really annoying me now .. did the guys who installed it made a mistake somewhere , should I close my ceiling vents In the winter ?

[@decliv]

@@nym5635 the insulation need to be push all the way touching the collard or you will have condensation. Oohh and mastic of course.

[@kendalgee5808]

@@nym5635 They say if you don't use mastic when installing the plastic duct onto the metal, it will sweat causing moisture, which eventually will saturated all of your insulation. So, brush a nickel thickness of mastic around the metal duct, then slide the plastic duct over it, this will create a waterproof seal and stop gaps for moisture to enter. Then clamp over it, then , pull up the insulation and foil, and foil tape it. Don't quote me, im not a pro. Just my .02 cents.

[@turboflush]

1:46 taped down.. to what? Itself? All your taping is the plastic duct to the plastic duct. Like taping someone to a chair but only wrapping the tape around the skin and never to the chair. The banduit is silly. It will help hold. Bit tape will hold and seal. Also compressing the insulation... is a no go.

[@kameronharrison3397]

For sure this duck will condensate terrible connection

[@tylerdirden3416]

how so, what would you do better. i like perfection, explain pls.

[@kameronharrison3397]

I've been installing and service for over 20 years in Florida when you put that Panduit strap on the outside of that duct liner you are killing the insulation value that duck will condensate you should only silver tape and maybe some Mastic let me explain one more time by you putting a Panduit strap on the outside of the installation of that duck you are destroying the R-value right where that Panduit strap is at on the outside of that duck will condensate and fail inspection in Florida other than that pretty good video

[@brandonluker4285]

@@tylerdirden3416 compressed insulation no longer insulates. So you have to wrap the connection with more insulation or that part of your ducting will be cold and condensate like a cold drink does

[@kirkey99]

Hah! Joke's on you! This is actually a chicken!

[@MohdImran-kf7gv]

It's not good way to put flexible. It's use aluminium tape only he didn't use clamp. It's a temporary way.thanks

[@tmuxor]

He did use a zip tie strap at around 1:20

[@diaperdood9369]

Why can’t we just zip tie it only?

[@chrissugg6781]

Terrible

[@jodykershaw7701]

Ya who cares if its not air tight…. 😂😂😂

[@chimpchaser341]

What's the point of the tape over the panduit? What i normally do is put the liner of the flex halfway down the collar, tape it from the base of the collar so that both half the collar and flex liner are taped. Then panduit and tightent the half that's on the collar. Otherwise, what you did seems to only have been putting tape over the liner and panduit, having it attached to nothing but that.