I'm new here, and have a question about a construction material HVAC contractors in the area are wanting to use. I've got a new central air and evap. coil, and it's different height/width than the old unit, so the original sheetmetal plenum has to be replaced. I'm trying to avoid ductboard, but finding local HVAC folks that do sheetmetal fab. is tough, everyone wants to use ductboard or flexible duct, and a few want to use this stuff.
My question is: has anyone here ever used foil-faced polyisocyanurate foam insulating board to make a plenum? It's foil-faced on one side like ductboard, but it's foam in the center. The heat ratings that I've seen on the stuff in home centers sounds more than adequate for a heating system, and shouldn't be a problem with a/c.
Is it becoming common for this to be used?
Is it safe? (RE: flammability, toxic gases, etc)
I may have the plenum part incorrect; its the area from the top of the evap. coil housing that connects to the main sheetmetal duct system that runs throughout the house. I think some folks call it a trunk line as well?