Have you ever heard the term “static pressure” in connection with your heating and cooling system?  Most homeowners will answer no to this question, but now you’re wondering what it is.  Much like our blood pressure gives some indication of our cardiovascular health when we visit the doctor, static pressure offers insight into the health of your HVAC equipment and ductwork.  As Austin heat and air contractors, we think it’s important for homeowners to understand what static pressure is and why it matters.

Static pressure occurs in the air ducts or ductwork of your system; if the static pressure is high it typically indicates the system is under an abnormal amount of stress.  This means your equipment has to work harder, as some issue with the system or ductwork is literally dragging it down.  Basically, the furnace fan moves cooled or heated air through the ductwork, delivering it to your indoor spaces. When this movement becomes sluggish, it creates high static pressure.

Some of the “symptoms” you might notice if static pressure is too high include:

Uneven airflow.  Whether it seems that the conditioned (heated or cooled) air is hovering in one spot or that there is very little air coming from registers, it could indicate high static pressure.  Many homeowners refer to this as hot and cold spots in their homes.  Certain areas may feel warmer or cooler than others; comfort isn’t consistent.

Noise.  We all prefer a system that runs quietly, however if the static pressure is too high you will notice more noise due to airflow restrictions.  Each time your system comes on you might hear a very noticeable “whooshing” sound.

In severe cases high static pressure can result in failure of components such as the compressor or blower motor, or even complete failure of your system.  Essentially, the more static pressure increases, the more it will drag down your HVAC system and prevent the air from moving around properly.

What causes high static pressure?

There are a number of things that can cause static pressure to become high.  It could be faulty installation of your ductwork or a problem with its design.  When there are numerous turns, dips, or bends in the ductwork it can impede good airflow.  Ideally, the solution would be to replace the existing ductwork.  If this isn’t a viable solution, consider generating improved airflow by replacing a traditional blower motor with one that offers variable speed.

It could be something as simple as your filter.  Those 1″ pleated filters are commonly used to filter the air, however it’s better to use a media filter with low pressure drop.  There’s a lot of air trying to come through a small filter, so those high MERV or thick filters designed to filter out tiny particles and pollutants restrict the airflow even further.  If nothing else, be sure to replace or clean your filter often.  A super dirty filter can contribute to high static pressure.

Does your HVAC contractor routinely check static pressure when inspecting your system or making repairs?  If you aren’t sure, just ask!  This is an important factor that can impact not only your comfort, but the longevity of your system and how much you pay in energy costs.

For all of your heating and cooling needs, count on the Austin HVAC experts at Schneider Mechanical.