I'm stumped, trying to design a zone system with a variable speed blower utilizing manual D but lookin at the vague info. they give in the booklet isn't helping at all. Its the american standard 16 seer, 4TEE3F65 for 5 tons but what they give for 2000 cfm on the airflow performance chart doesn't make any sense. I feel like I have to work this one out backwards and guess the ext. static aviailability. Any one have a solution?