The best I have seen is the ASHRAE self directed course material. Costs a bit but well worth it. Check ashrae web site. Subjects from Controls, to Fundamentals to Air Systems and more. Very well laid out and easy to understand.
russmech beat me to it but he is absoutely correct. The Taylor article is one of the best available on return vs relief fans. Speaking of minimum outide air . . .the April 2002 ASHRAE Journal has a pretty good article by Larry Felker. And finally, check out the Kele Controls web site for VAV...
Check out the ASHRAE Duct Fitting Database. Like the SMACNA data, there is a cost involved however. www.ashrae.org Also, engineering libraries may have a book "Handbook of Hydraulic Resistance" by Idilchik. University Libraries would be the best bet to find it.
