dpb wrote:
RicodJour wrote:
sid wrote:
I will visit HD or Lowes tonight.
Also, should I be concerned about adding these transitions and an
extra elbow ?
Will this add significant static pressure to this run ?

You have enough problems now with the four 90s in close proximity.
dpb's suggestion of using 4 45s would help with the static pressure.
I'd do the 45s in round duct and use the transitions just on the flat
rectangular run.
...
That would leave him still at the same bottom height once he made the
return to horizontal is the problem. He needs to get to the lower
profile earlier. He could do it in the transition, but I figured might
as well just go ahead and make the transition, then the detour.

That's not necessarily so. He'll be working it backwards from the
rectangular duct which is placed up tight against the beam. The
bottom of the rectangular duct will be the same as the bottom of the
round-to-rectangular transition.
http://www.pillsburysme.com/product_...arge/423-l.jpg
All of the height differential, connections and potential headroom
savings, will take place above that.

Reiterate what I said earlier and your agreement; this will be _less_
static pressure than previous using 4-90s. I don't see where OP gets
the "extra elbow" idea...

This I do not know. Maybe it's a time and materials job.

R