Understanding HVAC Air Filter Ratings

July 19, 2016

Understanding HVAC Air Filter Ratings | Lozier Air filters in your heating and cooling system serve the important function of helping to clean your indoor air. As air flows through your HVAC system, it passes through the filters. Particulates such as dust, pollen, fibers, and other material are trapped in the filter media. Filter effectiveness depends on the HVAC air filter rating.

MERV Ratings

The industry standard for filter effectiveness is the filter's MERV rating. MERV stands for Minimum Efficiency Reporting Value and represents how well a filter traps and holds particulates. The MERV rating indicates how effectively a filter captures particulates between 0.3 and 10 microns in size. To give you an idea of the tiny scale involved, keep in mind that human hair is about 100 microns wide on average. Standard MERV ratings span the numbers from 1 to 16, with higher numbers representing more effective filters.
  • MERV 1-4: These filters are usually very inexpensive, but their performance will be limited.
  • MERV 5-8: Filters with these MERV ratings are considered medium quality and are best of removing particulates of 3 microns or larger.
  • MERV 9-12: These filters are high-quality filters and are effective in most residential settings. They trap particulates of 1 micron or larger.
  • MERV 13-16: These very high quality filters can remove small particles below 1 micron. These are the highest filter ratings used in standard HVAC equipment.

HEPA Filters

If you need filtration at even higher levels, you can find air filters rated at MERV 17 to 20. These High Efficiency Particulate Air (HEPA) filters are used where indoor air quality is extremely important, such as in medical or technical environments. These filters can be very thick and will usually require specialized mountings. You should make sure your HVAC system can produce enough airflow to use HEPA filters; otherwise, restrictions in airflow could damage the system. Lozier Heating and Cooling has been a premier provider of heating and cooling in Des Moines for more than 100 years. Contact us today for more information on HVAC air filter ratings and for expert help choosing a filter for your heating or cooling system. Our goal is to help educate our customers in the greater Des Moines, Iowa area about energy and home comfort issues (specific to HVAC systems). Credit/Copyright Attribution: "Palto/Shutterstock"