"zephyr" wrote in message
. ..
Hey all,

I have a kitchen and living room separated by a load bearing wall that has
3 ducts and 1 cold air return running thru it.
I'd like to remove the wall and put in a beam. The new beam and the wall
removal I can deal with, but,
moving duct work is going to be a new challenge.

Currently there are 3 ducts coming off the main trunk line (in the
unfinished basement ) at separate spots in intervals of 16 inches (so the
lines fit up the wall cavities) they run west @ 6 feet off of the trunk
line before they turn up thru the wall I want to remove.
I'd like to take out the ducts, and run 1 large line off the main trunk
line. this new line would exit the main trunk line 1 foot north of where
last of the 3 current ducts located. (trunk line runs N/S)
I'd then remove the majority of the existing wall, then this new line
will run 6 feet from the trunk line then turn up next to the "stub" of the
remaining wall. Then when the new line reaches the ceiling turn it back
south in a ceiling bulkhead to rejoin the remaining duct work that runs
thru the floor of the second floor. The current ducts all open into the
same room which currently gets too much air with all the vents open.

I understand that running angles at 90' will really cut down on air flow
but, I don't think I have much of an other option.
My question is, If I remove the 3 lines and consolidate them, should the
sq footage of a cross section of the new square duct be larger / smaller
or the same size as the sum of the 3 existing ducts.

ie. given 3 pipes at 6 inch round then (6*6 / 2) *3 = 54 inches so new
square line off the trunk line should be 6x9 or so.


thanks in advance for any advice.

Dave
Dave Area for circle is Pi x r squared 3.1416 x 9 x 3 pipes is 84.9.
Been out of school over 60 years so someone may correct this. WW