How Do HVAC Filters Work?

HVAC filters are essential for the operation and longevity of your equipment, maintaining good air quality in your facilities, and for the health of the people in it. Changing air filters is a commonly known part of routine commercial HVAC maintenance. How HVAC filters work isn’t, but it’s useful for understanding the HVAC needs of your building.

What do HVAC Filters do?

Normal air contains a wide variety of contaminants like dust, dander, dirt, mold spores, pollen, hair, fibers, particulate matter, and so much more. Those particles can interfere with optimal operation of the HVAC system, so air filters capture the contaminants to protect the system. Filters usually feature pleated material to provide greater surface area for trapping particles and can be made in layers to further capture particulate matter. Electrostatic filters, fiberglass filters, and HEPA filters are other options.
How do HVAC Filters Work?

Air is either warmed or cooled after it is pulled into an HVAC system. Filters capture particulates as air is moved through the blower and then is pushed out through ducts, so those contaminants don’t build up and interfere with operation. Additionally, filters also improve air quality because they trap those particles.

HVAC air filter efficiency is measured as MERV, which stands for Minimum Efficiency Reporting Value. This provides a uniform metric for evaluating the performance and efficiency of HVAC filters.

The scale for the MERV rating is usually 1 at the low end and 16 on the high side. The greater the MERV rating, the more efficient the filter is at removing airborne contaminants with 16 being the routine high end of the scale, though some filters have been rated higher. When selecting HVAC air filters for your workplace, the higher filtration level you’re seeking, the greater the MERV rating you should select.

Hospitals and surgical centers routinely use HVAC air filters with MERV ratings of 13-16. Due to COVID-19 concerns, all facility managers and commercial building owners should consider a minimum MERV rating of 13 according to ASHRAE, with a MERV rating of 14 or greater recommended.

However, the HVAC system’s capabilities must always be a factor. High air filter efficiency can cause a pressure drop in the system, which, in turn, can cause decreased air flow, which then leads to increased fan (and energy) use to compensate. If a top-rated MERV filter can’t be used in the HVAC system, select the highest one possible.

What HVAC Filter Should I Use?

The choice of HVAC filter depends upon the type of system you have, the facility it’s serving, and operational needs. Manufacturer recommendations are the first place to start when selecting HVAC filters.

However, if your facility has specialized needs, such as high tech with clean rooms or surgical facilities and hospitals will need greater air filtration than the average office building. Even when buildings require more sophisticated air quality solutions such as HVAC UV light purifiers, choosing air filters with the right MERV rating is a key decision that needs to be discussed with your HVAC maintenance provider. Our experts at Donnelly Mechanical can evaluate your facility’s needs and make recommendations.

How Often Should Commercial HVAC Filters Be Changed?

As with the type of HVAC filter, how frequently those filters are changed will depend upon system manufacturer recommendation, the type of facility it serves, and its business needs. Typically, commercial HVAC filters are changed 3-4 times a year. Depending upon circumstances, and even the local environment can be a factor, a more frequent pace could be recommended. For example, hospitals and surgical centers might require HVAC filters to be changed every month or two for the best results.

Donnelly Mechanical Are the Experts in Commercial HVAC

At Donnelly Mechanical, we have an experienced team who are experts in HVAC systems and indoor air quality. If you are concerned about air quality or want to improve air quality within your facility or office building, call us at Donnelly Mechanical. We even have specialized solutions for hospitals, rehab facilities, data centers, corporate buildings, etc.

In addition to better air quality, we can also discuss upgrading your commercial HVAC system to help lower energy costs and improve the overall quality of life of the people using your facilities. With more than 30 years of experience, Donnelly Mechanical has NYC’s leading team of experts in commercial HVAC system efficiency. Contact us today.

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