What is a plenum box?
HVAC plenum boxes form a crucial part of the ductwork in any ventilation system. The plenum boxes connect grilles and square or round diffusers to air duct systems, by mean of flexible ducting of directly to ductwork. Plenum boxes are usually situated on either side of the fan or heat exchanger and have the important function of bringing in, distributing, and removing air. The plenum box can be made with acoustic insulation to reduce the sound into the system. They are the air’s first stop after being heated or cooled and its last stop before going back into your AC, heat pump, or furnace. Almost all systems have two plenum boxes: the supply plenum box and the return plenum box.
What is a supply plenum box?
The supply plenum box connects to the supply outlet of your furnace, heat pump, or AC unit. It receives the newly heated or cooled air directly from the unit, then distributes it to your ducts to be circulated through your home.
What is a return plenum box?
The return plenum box receives used air from the return vents and distributes it to your HVAC unit to be heated or cooled again. The used air must pass through a filter before entering the return plenum, ensuring that it’s clean before it reenters your AC, heat pump, or furnace.