What MERV Ratings Mean for Your Air FiltersWith so many HVAC air filters on the market, it can be difficult finding one that’s not only the best fit for your home’s central heating and cooling system, but is also effective at keeping dust and other types of airborne particles at bay. If you want to know which air filter works best at keeping your indoor air clean, you’ll want to learn about MERV.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) came up with the Minimum Efficiency Reporting Value, or MERV for short, to measure air filter performance. Under MERV, air filters are rated on a scale of 1 to 16 (with 17 to 20 reserved for true HEPA filters). The higher the rating, the more thoroughly an air filter can capture airborne particles as small as 0.3 microns.

Here’s a small sample of what you can expect an air filter to pick up at each MERV level (at each higher level, a filter generally can capture everything that lower-rated filters can remove):

  • MERV 1-4: Most types of dust, pollen and dust mites
  • MERV 5-8: Mold spores and pet dander
  • MERV 9-12: Car exhaust particles and Legionella bacteria
  • MERV 13-16: All bacteria; most smoke, face powder and paint pigments

According to the U.S. Environmental Protection Agency, filters with a MERV of 7 to 12 are just as effective as true HEPA filters at removing most airborne particles.

Keep in mind that a higher rating does not automatically mean better performance. As MERV ratings rise, the pores within the air filter shrink in size. This generates more resistance in air flow, which can cause a HVAC system not designed for that particular filter to work harder. Not only can this potentially damage your HVAC system, but it also degrades indoor air quality due to the reduction of air flow through the filter. For this reason, the National Air Filtration Association recommends filters rated at MERV 9 to 12 as the highest for residential systems.

To learn more about MERV and the impact it has on air filters, contact us at Mowery Heating, Cooling and Plumbing. We proudly offer our expertise and services to the Greater Indianapolis area.

Our goal is to help educate our customers in Brownsburg, Indiana and surrounding areas about energy and home comfort issues (specific to HVAC systems). 

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