Air Filters: How They Work and How They are Rated

Clean Air
Image from filtersfast.com

Changing your air filter is probably a job most homeowners are capable of doing on their own, but understanding why a clean fresh filter is important may change the way you think about this “simple” job. Despite what most people think, standard air filters do not have a significant effect on the quality of your indoor air, instead their main purpose is to protect the heating and cooling system from damaging particles and contaminants. In order to improve the air quality within your home, installation of a higher efficiency filter is necessary.

How are Filters Rated?

Air filters are rated using the Minimum Efficiency Reporting Value (MERV) system. The higher the MERV rating, the fewer contaminants and particles can pass through the filter. The system rates or measures in microns with a rating generally falling between 1 and 16, however some specialized systems can achieve a rating above 20.

Filter Comparison Chart
Image from qualityfilters.com

So now that you have a better understanding about filters and how they are rated, here are a few filtration choices to think about for your home A/C system.

  • Standard Efficiency Filters – These are the flat or panel style filters that are most common and are typically used with standard A/C systems. The MERV rating on this filter is usually found between 1 and 4. As we explained earlier, most of these filters are designed only to protect the system from contaminants such as dust and pollen. They are not designed to filter fine particles such as viruses, mold spores, bacteria or allergens.
  • Medium Efficiency Filters – These filters typically have MERV ratings from 5 to 13 and have been shown to be very effective at catching multiple air quality contaminates. In fact, they have been shown to be almost as effective as a true HEPA filter according to the U. S. Environmental Protection Agency (EPA). Filters in this category both increase overall efficiency and greatly improve home air quality especially for individuals with allergies or asthma. Filters with MERV ratings at a 12, are capable of trapping extremely small particles (less than 2 microns) and function very effectively at removing allergens including pet dander and pollen from the air system.
  • Higher Efficiency Filters – These filters are generally installed only through professional companies and have MERV ratings from 14 to 16. These are most commonly found in commercial health care operations, where air filtration, cleaning and purification are vital. For those out there who like details, these filters can remove up to 40% of volatile compounds and odors, filtering items less than 1 micron in size including bacteria and molds. While these filters are not commonly found in household applications, with custom design these filters can be used in residential application creating the most efficient option for home air quality control.

We hope this information has been helpful, and will give you a better understanding of your home A/C system and the role a clean correctly chosen air filter has in the heating/cooling/purification process. Please keep in mind, as with any change or upgrade to your home’s HVAC system, we recommended that you consult an expert prior to installing new components. Here at Taylor Refrigeration and A/C, we have dedicated technicians who can evaluate your system and recommend the best filtration product for your specific needs.

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