A supply air plenum is a sheet metal box that attaches to the outlet of a furnace or air handler, and is used as a central manifold for other ductwork to connect to. As the air blows from the furnace or air handler, it flows through the supply plenum and any ductwork attached to it. The sizes of the supply plenums available here fit the furnaces and air handlers we sell. Each supply plenum consists of 5 sides that connect together for easy assembly. (If you are installing an air conditioner with a cased evaporator coil connected on top of the furnace, the supply plenum will attach on top of the cased coil.)
Watch the installation video, linked below, as a pro quickly assembles the supply air plenum and attaches it to the equipment, and shows you how to do the same. You'll have all your questions answered as you see how fast and extrememly easy it is to put together. Plenum assembles in about 5 minutes.