Trimming duct work

[Lee Schierer]

I need to shorten a top outlet from the main distribution duct in my hvac system. It is an 6" diameter outlet and the duct is tight up against the bottom of the floor joists. I cannot take down the main trunk line. I have an opening that is 9" high x 13 wide and the outlet sets in the center on an 18" wide duct that runs perpendicular to the floor joists. Any suggestions on how to trim off about 2" of the metal outlet duct?

I'm open to suggestions.

[Jim Becker]

Since you cannot remote it (at least that's what it sounds like), I think you're going to have to drill a starter hole and nibble it away with shears.

[Jerome Stanek]

this sounds like a job for a multitool or grinder

[Lee Schierer]

The tin snip idea is what I did on the first one and it was a pain to do but it eventually got the job done. I'm going to try the multi tool to start this time. It will be loud with my head up between the floor joists and the multi tool at head level. I may end up back at the tin snip method.

[Jim Becker]

The biggest challenge is to do this without ripping the flesh of your hands and writs so you look like a Halloween zombie... :D

[Lee Schierer]

Well, the job is done. The Oscillating tool (mine is a variable speed Bosch) worked quite well. Fortunately I could rotate the collar so I didn't have to reach over the sharp edges. I just sort of rocked the blade back and forth across the surface and it cut pretty quickly with the metal cutting blade. Just a few sparks. The new elbow is in place and the heat is back on.