Hi,

I am going to install a vented(horizontal) range hood in my new house.
My builder setup the ductwork as following: range to duct and then
straight DOWN about 6 ft and then a 90 degree bend (another 6ft) to the
outside.

I don't think this would work. The efficiency is going to be very very
poor. I need some proof and support to convince my builder.

What do you think?

Thanks,

haucy