Ductwork 101???
 

Reading the post about the pitfalls of closing off hvac ducts in unused space reminded me of the mess of ducts in my crawl space - i have a long rectangular discharge duct for my heat pump with a series of 6" round flex ducts, one for each floor outlet, tapped off it in rows on both sides of the rectangular duct - they hang like a mess of snakes in the crawl space.
I wanted to consolidate 2 of the flexducts that go to closely spaced registers in the same room by blanking off one at the larger rectangular duct and enlarging the other to 8" and tapping both registers off it but was told by a ductwork guy that it just wouldn't work - claiming they simply arn't designed that way.
Do you really need a separate line tapped in sequence off the main trunk for each register? The duct guy even said the spacing of the taps was done with a complicated formula. I think its done with budweiser in my case !
Anyone with any help on this? Maybe a pointer to a simple Ductwork 101 primer?

Just Google " balancing HVAC ducts" or something similar. It is science, but not super complicated to do. While you're at it, do an energy audit. Contractors charge lots of money to do this not that difficult task.

How to Balance a Residential HVAC System