Duct work help

[Chris47]

First of all I like to say to all new here and for some reason I cant explain Ive always been drawn to HVAC so here goes.

At the end of my trunk on a split system I have a 48x9x7 piece i would like to make smaller for head room in a lower bath room, within that piece I have a six in round running 20 feet to up stairs livingroom. If I find the volume of the piece which is 3024 and just come up with a different configeration like 48x16x4 which is 3072 would that have any affect on force. House is just under 1500 sf and I have a new 80000 btu furnance.

Chris

[Diceman]

So ya get 3 more inches of headroom?
I don't have my ductolator but it should work.
Make sure the round take offs don't stick down into the trunk.

Drawn into hvac????
Really??

[PapaFuse]

You are standing too close to the return.