Can I put a "U" turn in my range hood exhaust duct?

Question

In the photo below The red arrow represents the direction of the exhaust, as you can see there is a load bearing joist in the middle which I can't cut. I'm planning to build a recessed ceiling on that spot, so I can bend the exhaust in a 'U', going down and then up again, using 4 elbows.

I have had somebody say it wasn't a good idea because the grease will accumulate there, and be a fire hazard. What are your opinions on this? I'm kind of running out of ideas here and this feels better that cutting any kind of hole in that joist.

Answer 1

The person that told you grease will collect there was correct. The other issue is each bend creates flow restrictions reducing the flow from the blower. Everything may work fine with 1 or 2 elbows but 4 is beyond the norm and your hood may not work well plus the built in grease trap.

I would try and lower the hood 4” and box that in it may look “different “ but a straight run until you can go up would be a better plan.