A Plenum is an Air-Distribution Box attached directly to the supply outlet of the HVAC Equipment that heats or cools the air to make the room temperate. The Ductwork that distributes the heated or cooled air to individual rooms is connected to the Plenum Box.
DVAC Plenum Boxes are of 3 Types:
1- Slot Plenum
2- Linear Plenum
3- Plenum Box Diffusers