Quote Originally Posted by vstech View Post
This is TOTALLY incorrect.
you have to radius the inner bend on a 90 to have ANY effect on airflow. without it, turning vanes are still needed...

radiusing the outer bend only saves metal costs...
Seems to be a professional difference of opinion on this point.

I'm not an engineer but I think I have a basic understanding of fluid flow. If I were building the return drop in its present location, I would have made it the full 20X25 size of the filter box all the way up. and included turning vanes.

With the overall leakage of the panned joists, I'm not sure if this would just be perfuming the pig, though.

Thank you for any more thoughts.