HVAC/ Tin knockers? Anyone here install for a living?

[M-technik-3]

I am redo my home's central AC/Heat ducts and need some pointers and tips.

[10Toes]

http://www1.resnet.us/conference/2009/presentations/Stroer-ACCA_Manual_J_Load_Calculation-An_Overview_for_the_Energy_Rater.pdf

[M-technik-3]

That is great but I have newer high efficiency unit but was installed with no regard to second floor. I plan to use a mini-split on the second floor for cooling but would like to add a floor return from my second floor to scavenge heat /cold air.

I am currently at a stand still with building my return box. I need one that will pull from two rooms so my plan was to purchase a unit that has room to have an extra duct come into the return.

Understand?

http://www.ductworks.net/xcart/home.php

found this site trying to review some stuff here.