PLENUM BOX

WHAT IS A PLENUM?
If you've ever had work done on your furnace or air conditioner, you may have heard your contractor mention a problem with or relating to something called a "plenum." No, it's not a made-up word created to upcharge you! The plenums in residential HVAC systems serve very important functions. Read on to learn more about this vital component of your home's heating and cooling.

What Is A Plenum Box?
In residential HVAC, plenums are more accurately referred to as "plenum boxes," which form a crucial part of the ductwork in any forced air system. Generating hot or cold air is only half of your AC, furnace, or heat pump's job. Once it has heated or cooled the air, it must then move that air through ductwork, circulating it through your home. After the heated or cooled air circulates through your house, it comes back to your HVAC unit, which draws it in to heat or cool it once more. 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. 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.