Timeline for How to run a flex duct branch through a unreachable trunk?
Current License: CC BY-SA 4.0
12 events
| when toggle format | what | by | license | comment | |
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| May 11, 2021 at 0:36 | comment | added | K H | @VickyP You could ask him what concerns he has, probably because it's better for the inside of the duct to be smoother. A duct worker would be more likely to access tools to do an awkward cut or simply take down a section of the duct temporarily. That said, I've seen numerous wrong holes being put into ducts, and if it's prohibitively expensive to replace that section of duct, they just get permission to patch it. If you weren't sensible about the size and location of the hole, you could decrease the rigidity of the duct. | |
| May 10, 2021 at 16:07 | comment | added | PowerTech | @K H, One of the HVAC guy came and said, its not good to make a hole from bottom and then patch. Why he would have said that ? | |
| May 6, 2021 at 3:08 | comment | added | K H | You can use those to line the flange up and drop it into place, pop screws into a few other holes, then pull the nails and replace them with screws and paint some more mastic onto the outside. Awkward to reach, but usually quite doable. | |
| May 6, 2021 at 3:06 | comment | added | K H | I'd try to figure out a way to install it from the outside as then you'll only need a single 5" hole saw cup. You could hole saw both holes, then use a long bit to drill pilot holes around the top side hole and get someone to hold the flange in place while you mark those holes on to the flange. Take the flange off and drill holes to match and then you should be able to mastic and screw it in place by reaching with a stubby screwdriver to the top side. A trick to get the holes aligned would be to mastic the face of it and get someone to hold a few fine nails up through the hole in the duct. | |
| May 6, 2021 at 3:02 | comment | added | K H | I'm not sure if it's allowed, but I would not use mastic alone to attach it. Use self tapping hex head screws with a magnetic socket and extension bit and use the mastic to seal. A cursory search would seem to indicate it's OK to use mastic on the inside of a duct although it will smell until it cures and it's less smooth so there may be extra dust buildup between cleanings. You probably need a 5.5" hole saw to attach it from the inside for the hole the neck passes through and a 6.5-7" holes saw for a bottom hole large enough to get a flange through. | |
| May 5, 2021 at 23:07 | comment | added | PowerTech | Thanks I gotch you . can I use mastic sealant from inside to attach collar ? | |
| May 5, 2021 at 22:55 | comment | added | K H | @vickyP If you're attaching the flange from the outside, you only need a 5" hole to make a 5" hole with a holesaw. If you're attaching it from the inside, the bottom hole has to be large enough to fit the wide part of the flange that overlaps the edges of the upper hole. It's sheet metal so an option to reduce total hole size is to bend it, put it in and unbend it. | |
| May 5, 2021 at 16:18 | comment | added | PowerTech | @K H. i didn't understand your last statement "unless you fold the flange to get it in and then somehow unbend it ship in a bottle style" ? | |
| May 5, 2021 at 4:14 | comment | added | K H | @VickyP actually now that you make me think of it, a 5" hole would probably allow you to screw in and mastic the flange from the inside with aircraft bits and then all you'd have to do on the top is reach over and get a compression clamp and a wrap of tape on. You'd need a significantly larger hole on the bottom side though unless you fold the flange to get it in and then somehow unbend it ship in a bottle style. | |
| May 5, 2021 at 3:51 | comment | added | PowerTech | I would prefer to go with 2nd option. First cut a bigger hole from opposite/bottom side to make the required hole to the top from inside. install a collar and duct to the top. then patch and seal the bottom hole with metal sheet. only problem is how to seal/tape the collar from the top. | |
| May 5, 2021 at 3:13 | comment | added | Platinum Goose | I think your first paragraph is the right answer. If a 90 degree drill adapter is used that has the added benefit of reaching further into the joist cavity. Looking at the first picture with the tape measure it appears the center of the hole is 30 inches from the soffit. Even a larger person should be able to get their arms into the joist cavity far enough to reach the center of the hole with a drill using a 90 degree adapter with a low profile hole saw. Drilling up through the bottom is also a good option. | |
| May 5, 2021 at 2:13 | history | answered | K H | CC BY-SA 4.0 |