In remodeling my bathroom I had to convert a 6"x6" square duct underneath the floor joists in the basement to flex so I can get around my new toiler drain. I cannot for the life of me find a 6"x6" square to 6" round transition anywhere.
Do I need to fabricate one myself? I don't know what to do.
I am aware that a 6" round duct is smaller than 6"x6" square by ~20%. It feeds the foyer which I have kept the damper nearly closed anyways because it gets very hot/cold in that location.