So you think it's more important to have a 1.18" (pipe/runner ID) spacing between bell mouth and plenum wall than maximizing runner length?
I guess should put a plexiglass lid on top of the plenum, put a vacuum cleaner on the pipe and have a source of smoke for the plenum inlet and have a look at the flow pattern around the bell mouth as I move it towards/from the plenum wall.
Finn
(Printing it with bell mouth up now, hoping it won't collapse or sag).
On 9/19/2019 11:40 AM, lehanover
lehanover@aol.com wrote: