Purpose:

A supply plenum is a sheet metal box that attaches to the outlet of a furnace or air handler, serving as a central manifold for connecting other ductwork. It ensures even distribution of conditioned air throughout the system.

Materials:

Typically constructed from galvanized steel for durability and resistance to corrosion. Some models may feature insulation to reduce noise and improve energy efficiency.

Insulation:

Not all plenums come with internal insulation. For instance, some models are unlined, while others may have foil-faced insulation or duct board linings. The choice depends on the specific requirements of the HVAC system and local building codes.