I have a low pitched roof, and a 7" branch duct that crosses the main access
route. The branch has gotten crushed on several occasions. The original duct
was cardboard type material.
I built a little "shelf" to protect it, but it would be nice to have a
little "play" in the duct.
It's about 7' from the trunk to the stackhead.
I've thought of a few options, but I'm not sure which would be best.
- Use insulated flex for the entire 7'.
- Use 3' to 4' of insulated flex right off the trunk, and use 3' to 4' of
round metal pipe to the stackhead.
- Use 7' of round metal pipe, and hope it lasts longer than the old duct.