I've known I need to replace the 12" return air ducting in my attic for a while, insulation is falling off in several places. So, got to looking around and I notice that there are holes around the ducts where they connect to the return air 'box' on top of the unit. The box was built with what appears to be duct board and also needs replaced. I'm going to DIY it, since that's my way.
The hole at the top of the furnace is 20x20. They reduced that down to about 18x18 and went to the attic with that.
My dad, by some random chance has a new, extra, galvanized steel box from when they built their house. It is 16x18x47. I'm thinking I'll build a flange that will reduce to that and use it. I figure the dimensions for the metal box are close to what's there insofar as inside measurements.
Questions
1) any reason I should not do what I'm planning?
2) what should I use to insulate the outside of the galvanised plenum box? Can I just wrap it with some plastic-faced batts or would that create condensation issues?
Any thoughts are appreciated.
The hole at the top of the furnace is 20x20. They reduced that down to about 18x18 and went to the attic with that.
My dad, by some random chance has a new, extra, galvanized steel box from when they built their house. It is 16x18x47. I'm thinking I'll build a flange that will reduce to that and use it. I figure the dimensions for the metal box are close to what's there insofar as inside measurements.
Questions
1) any reason I should not do what I'm planning?
2) what should I use to insulate the outside of the galvanised plenum box? Can I just wrap it with some plastic-faced batts or would that create condensation issues?
Any thoughts are appreciated.
