[-MG-]

I am finishing a room (except ceiling which has been painted black), and I am installing a vent hood and the end of this duct work is about 2 inches too long. It looks like there is about 3' of extra ductwork that doesn't go anywhere, the last vent is in the picture:

So can this be cut and capped off like it is now? How would you cut it? I only need to cut maybe halfway down the first portion of before the support bracket.

 

[ben's plumbing]

we use a nibbler...you could left ,right,and straight cutters...electric shears,,or you could remove last section of trunk line cut cap and reinstall it..ben sr

 

[-MG-]

And it's no big deal to do that? My only question is why did they install the extra portion.?

 

[jagans]

If you dont have a nibbler, and most DIYers Dont, Maybe you have a right angle grinder? Bosch makes a great one. Install a thin sheet metal blade, square down and across and cut that sucker right off. Wear safety glasses and don't start a fire.

 

[carmon]

If you dont have a nibbler, and most DIYers Dont, Maybe you have a right angle grinder? Bosch makes a great one. Install a thin sheet metal blade, square down and across and cut that sucker right off. Wear safety glasses and don't start a fire.

oh my.....

 

[bobinphx]

you could also use a jig saw with a metal cutting high tooth per inch count blade. I would not use a grinder unless you have about 12 to 24 hours to perform an onsite firewatch!!!! or wet down the whole area after you are done. (father in law was a safety inspector and taught me some things!!)

one other thing to do, since you are in there, is to get some duct mastic and seal up inside as far as you can reach into the duct, then do all the outside seams of the duct, prior to installing the ceiling!!! good stuff that mastic, saves you money in the long run (but its messy to work with!!!)

as to why the duct end is so long.... here is a quote from this site

http://www.rses.org/assets/serviceapplicationmanual/630-148.pdf

Never start a branch run from the end cap of an extended
plenum. For best results, the starting collar of
a branch run should never be any closer than 24 in.​

from the end cap.

have fun and be careful of your fingers, toes, eyes and ears!!!!

 

[jagans]

Well if you use a jig saw, wear a mouth guard, because your teeth are going to rattle. :laughing::laughing::laughing:. Platen snips are great too, once you get a starter hole. I have these in left and right, wiss, of course. I just thought he might have a grinder. Right on re the fire watch, but this is sheet metal, not much mass like grinding red iron. If he sprays water with a simple sprayer he should be fine, besides it gives him a chance to stare at the ceiling while having a beer, or a glass of schnapps. :wink: Or even a bone if hes in CO!

 

[ben's plumbing]

And it's no big deal to do that? My only question is why did they install the extra portion.?

they did not want to do what you are trying to do ...cut trunk off:laughing::laughing::laughing: ben sr