How do I build a return air plenum out of a sheet of duct board?

Question

My boyfriend and I are doing home renovations ourselves to save money. We got a new gas furnace and coil and placed it in the attic on a platform. We also have a metal plenum for the flex duct to connect to. We are putting the return air in the ceiling, therefore we need a fresh air type plenum to attach from the unit down (in a 90 degree angle) to the return air. My AC friend gave us a sheet of duct board and told us to make it ourselves (its easy). Now he is MIA? How do we do it?

Answer 1

I am from South Florida and do a/c work here but let me tell you a few things first flex duct with gas heat does not match up. the gas heat will melt the duct in the winter time and cause a fire. Flex duct is made of plastic and can not take the heat. do not try to saving money this way in the long run it might cost you a bunch more.

Answer 2

I could show you but it's not something that can be explained in a paragraph because if you only have one sheet,a small error will cause you to need another sheet very easily.

Call your friend that gave you the free sheet of ductboard.