My trial and result:
I cannot make use of the Design-bar's Duct to create duct model for some sharp-turns. I tried with Menu-bar's Modelling with solid extrusion at Floor Plan. However, I cannot make it (say "A" the duct made by solid extruction) at the correct elevation to match the duct (say "B") created by Design-bar's Duct. Change of offset value of A does not change the elevation; It stay in same position by 3D views. Trial on changing setting in Element-Properties did not change elevation neither.
Question:
Create vent-duct by [Modelling\Create\Duct Fittings is a right way?
Thanks for help!
Revit MEP 2009 user