What Is Static Pressure In HVAC?

Static pressure is the resistance to airflow in the ductwork, which heating and cooling systems need to circulate warm and cool air throughout the home.

So, why does static pressure matter to homeowners? High static pressure can wreak havoc on your HVAC system, causing fans and blowers to work harder than they need to. High static pressure must be corrected once it is noticed.

High Static Pressure Signs

High static pressure brings on persistent noise within your system. It may be just a bit louder than normal, but in some cases it can become quite loud. This happens when airflow is restricted and it worsens when the system heats up. The noise you hear can be coming from anywhere in the system.

Warm air carries contaminants more easily, so the air quality can decrease. The air will carry more contaminants to the next room if it must pass through a restricted pathway. When there is high static pressure, the heat may only blow to one area of the room. This can create hot and cold spots, making it hard to feel comfortable no matter where you sit in a room.

High static pressure can result in higher energy bills. The higher the pressure, the larger the workload for your system. Energy bills will likely skyrocket and the system’s lifespan will shorten.

High Static Pressure Causes

Let’s take a look at the three main culprits of high static pressure below.

Dirty Indoor Coil

As air passes through the indoor coil, it is either heated or cooled. The coil is where dust accumulates and if the filter is not up to snuff, you may experience static pressure building up. This happens because the dirty coil has a hard time moving the air.

This situation can worsen if the coil is dirty or too restricted on top of already having a higher output than its return can accommodate.

Air Filter Is Clogged

A clogged filter will slow down airflow. Static pressure ultimately rises when the airflow is slowed. “Too restrictive” means the filters are too small for your system. It’s crucial to use the proper size filter to prevent this from becoming a problem.

Air Returns Are Undersized

The air returns in the room should be sized appropriately to match the air output of the system, typically measured in cubic feet per minute. If an undersized return is related to an oversized output, high static pressure will occur.

This problem is actually quite common. Thankfully, it can be resolved quite quickly by simply installing a return that better matches your system.

Conclusion

High static pressure can lead to a decreased lifespan for your system. Higher workloads will, of course, wear down your unit. For instance, when fans and blowers work harder to push air, they can overheat and burn out. The compressor could also take on too much pressure and wear down.

Always be wary of the static pressure within the system. This can lead to a lot of damage. It’s important to keep the return vent properly sized and clean the filter and coil regularly.