hello, a couple of weeks ago I posted a question regarding raising the main
rectangular duct trunk up 4 inches to gain headroom in my basement. Thanks
to all who responded. Raising the main trunk will be the easy part. It's
the transition piece that I am unsure of...
I will need to get some sort of galvanized 4" riser. If I make one myself,
how long should the riser be? In other words, to help the airflow, I don't
think I should use an elbow. My thought was the riser should gradually
taper up 4" over a couple of feet. Also, if I screw this up, any ideas what
it would cost a sheet metal guy to make one of these? The duct is
rectangular 18" x 10".
Thank you for your time.