sid wrote:
....
Can I find pieces that will replace the current elbows ?
All this contractor did was elbow it down under the joist and back up.

Prefab, probably not, at least at the box stores.

I see several choices depending on what your actual situation is wrt
routing.

The "best" would probably be to go back some distance on either side of
the glulam and insert a round to rectangular transition, go to a 45, add
sufficient length to reach the next 45 to horizontal transition, carry
it under the 'lam then reverse the sections on the other side. This
will give you the clearance at the low point with the side benefit of
minimizing and reducing existing pressure drop in the existing 4-90's at
the cost, of course, of making the transition on both sides longer.

Sorta' like (you'll need non-proportional font for this to have any
chance at all)...

| |
O O O - -- | | -- - O O O
\ |_| /
\-------/

where the "O" is the round and the "-\/" are the rectangular sections
and the arrows indicate the transitions. You could, of course, do the
first to elbows in round and transition going down but am assuming
you'll need that to be as tight as possible.

You may need the rectangular 45s made at a tin shop; the rounds should
be readily available or could use the adjustables if not.

A good tin shop is your friend...

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