Plenum in HVAC

A plenum is part of an HVAC system, a box or duct that brings in or distributes air. Each home has two plenums. A supply plenum takes in the new air from the heater or air conditioning system and distributes it through the HVAC’s ductwork. A return plenum pulls in used room air and sends it back to the core HVAC system.  

Example: Thanks to the plenum, air is brought in, is run through the system for filtering and conditioning, and is distributed evenly throughout your home. And like the rest of your HVAC system, when the plenum is kept clean, it helps the system in your home or business run more efficiently, saving you energy and money.