Understanding HVAC Air Filter Ratings

When considering the correct air filter for your needs, there are some things to consider. Using the air filter ratings written on the boxes will help clue you in to which air filter would be best for your home needs. There are two main acronyms to familiarize yourself with:

MERV – MERV, or the Minimum Efficiency Reporting Value, measures how effective the filter is at catching particles. The scale goes from 1 – 20, where 20 is the most effective and best-performing filter.

HEPA – The HEPA scale, or the High-Efficiency particulate arrestance scale, tells you just how much the filter traps. In the higher ranges of the scale, the filters can catch up to 99% of the particles going through them. These aren’t recommended for residential use because they restrict so much air flow, but they exist for places that cannot allow any sort of particles to get through, like a biochemical lab. This scale is also 1 – 20, where 20 is the best performing filter.

If you’re unsure which filter to purchase, ask your HVAC technician or check the MERV rating that comes with your filter. If you’d like a short guide on which filter to pick, we have provided one below:

  • Ratings 1-4: These filters mostly consist of fiberglass, which are mostly used to keep large harmful particles out of the HVAC system. They aren’t meant to severely improve the air quality.
  • Ratings 5-13: These filters have a higher surface area than the flat fiberglass ones and tend to be pleated. The higher end of these “medium-density” filters can trap up to 95% of particles down to 3.0 microns in size.
  • Ratings 14-16: These filters are typically only used in professional environments because they restrict so much airflow. If these high-end filters are what you need, you may need to modify your existing HVAC system to tolerate the reduced airflow.

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