What Is A Plenum Box Used For In A HVAC System

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Forced air HVAC systems tend to be the norm in today’s home construction or renovation. Through a series of ducts and vents, warm or cold air is pushed through from the unit’s blower fan. In order for everything to work properly, the HVAC unit requires a plenum to accomplish the tasks.

What is a Plenum

The plenum within this form of heating and AC unit is an air distribution box. It is directly connected to the supply outlet. On top of passing through a filter to remove dirt, dust, and other contaminants, the air pushed through the ducts must go through the supply plenum.

Hence, this is the reason the air filters must be replaced or cleaned on a regular basis. When these get too dirty, the warm or cool air may get to the supply plenum but not any further. Thus, what comes through the vents is reduced, if anything comes out at all.

In addition, if it’s coming from the air conditioner, the blockage will freeze the inside of the plenum. In turn, other components behind it will shut down as well and damage both the HVAC unit and the outside cooling fan.

In addition to a supply plenum, there’s also a return version of the box. When fresh air is pumped into the rooms, the used air is sucked back into the ducts and vented to the return plenum. Since there are air filters in this unit as well, the return air gets cleaned and recycled into the supply plenum for delivery.

In the end, you can think of the supply plenum as the recirculating air system on a vehicle. When that is activated, outside air is no longer collected from the air conditioner unit. Instead, the system reuses the original air that’s pushed through to continue cooling the vehicle’s interior.

The best way to maintain the supply and return plenums is to keep air filters clean. As mentioned previously, dirty filters block both the supply and return of the air. For the former, it means new hot or cold air does not reach the desired vents. For the return, it means a potential for contaminants like mold spores to spread in various rooms.

Keeping these filters clean helps to maintain the proper operations of a plenum. In addition, a regular cleaning of the vents will also help maintain the plenum’s abilities as well as its longevity. Call us today at 408-295-2182.

Hiring a mechanical engineer for building retrofits, rebuilds, additions, or enhancements is the quickest and surest way to obtain the ideal facilities for supporting your operations. Are you ready to make your workplace more modern, efficient, or compliant? If so, we can help.

Call us today at 408-295-2182.


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