BS_ncarb Vignette 1st try, please comment!

[jyll]

1. Does the arrow pointing to supply and return duct mean anything?
I am connecting the supply air duct opposite from the arrow direction.
2. Is it important for main duct to NOT overlap beams and girders? meaning going in between them?
any min. distance requirement?


also, any suggestions of alt vignette will be much appreciated.