Vent Bowl Ducting

[threechrome]

It seems I am having trouble sourcing the 2.5 inch ducting like others before me.  Does anyone have any opinions about using silicone ducting?
The two options I was considering were 2.5 inch diameter silicone hose...or a 2.5 to 3 inch diameter silicone adapter? The adapter would just make it easier to find the 3 inch ducting. 

[edtbjon]

There are several ways of "solving" this. First, I did measure the exhaust temp during a roast at the exit point of the exhaust bowl and it wasn't very high (70-75C/160-170F), even with safety margins, you wouldn't hit 100C/212F. I.e you don't have to worry too much about the heat melting things at that point in the exhaust chain...
I personally found a 60mm aluminium hose used in cars for heat distribution (for connecting to the de-mister etc...). I had to cut that up a little bit and repaired it with some aluminium tape. A hose clamp and I was ready to go. I think that many of us simply take a 3inch hose and "shrink" it with a hose clamp to fit. (I was about to order a 2.5 - 3 inch silicone adapter with a 45deg bend, but then decided for a solution with a cyclone instead (but that's another story...).)

[threechrome]

Thank You for the temp. numbers. I ended up going with the silicone adapter.  I'm getting excited to get roaster fired up but one step at a time for me as I have a steep learning curve ahead of me. Has been fun.

[Wayneg1]

I use a standard dryer hose with a hose clamp.  The hose is crimped at the exhaust bowl but it seems to work fine and it didn't cost that much.

[hankua]

I've also used automotive exhaust adaptor's 2.5" to 3".