When the combustion air duct is connected directly to the return plenum for a furnace, the blower fan on the furnace pulls outdoor air in to the return plenum. To supply this air to the furnace room, ...

Incorporating a plenum can have its design advantages, but corridors serving adjoining areas of health care occupancies are prohibited from being used for a portion of an air supply, air return, or ...

As many contractors attest, a supply air plenum is a sheet metal box attached to a furnace or air handler’s outlet and is used as a central manifold connector for other ductwork. As the air blows from ...

Q: I’m confused about maintenance of my crawlspace, which also serves as a cold-air return plenum for an oil furnace. No cold-air return ducts, just crawlspace. The crawlspace looks quite dirty, and ...