What is a MERV?

What is a MERV Rating and Why is it important?

Filter GroupThe filter in your HVAC system plays two important roles in keeping the unit operating at peak efficiency. First, it protects the system’s interior against damaging dust, and second, it helps maintain indoor air quality.

Your home’s location, square footage, and living conditions will usually determine filter replacement frequency. Experts recommend monthly filter inspections, and replacement; for homes that have pets, or homes that run the unit more than six months per year. Otherwise, replacement every three months may be adequate.

Air filters range from, inexpensive and moderately effective, to expensive and very effective. MERV ratings can help you choose the proper filter for your air quality needs. MERV– which stands for “minimum efficiency reporting value”- measures how effectively a filter removes particles from the air. These ratings range from one to twenty, with one performing the lowest and twenty the highest.

MERV Definition

MERV 1-4

Filters with this rating provide minimum protection. They’re flat and made of fiberglass. They catch particles at least 10 microns and up. Pollen, dust mites and roach debris would be the type of particles trapped by this filter. They don’t last as long as the better filters, and do little to improve indoor air quality.

MERV 5-8

These medium-quality filters trap between 20 and 70 percent of everything larger than 3 microns. This includes pet dander, mold spores, and dust mite droppings. According to the U.S. Environmental Protection Agency, filters with MERV ratings of at least 7, are almost as effective as HEPA filters when it comes to removing hazardous pollutants.

MERV 9-12

These are the best-quality air filters that an unmodified residential HVAC system can accommodate. They trap up to 90 percent of particles between 3 and 10 microns and up to 70 percent of particles between 1 and 3 microns. A filter of this quality can help control or minimize COPD, allergy symptoms, and asthma attacks.

MERV 13-20

Hospitals and manufacturing operations use these filters. They remove particles down to .3 microns, including all bacteria and viruses. Residential systems will require modification to accommodate filters with these ratings.

MERV Chart

If you’re considering upgrading to a better filter, it’s essential to check the specifications of your system to determine the highest MERV rating it will accommodate. The proper balance between your indoor air quality needs and your system’s airflow will prevent overheating and ensure peak efficiency. Don’t let price discourage you from using the best filter possible. A number of companies sell discounted filters. Discount Filters, on average, will save you money and work just as well as their higher priced counterparts. 

4 thoughts on “What is a MERV Rating and Why is it important?”

  1. It seems to me, the denser the filter, the more dust it would capture. Therefore, wouldn’t this also mean the less efficient the central air system would be?

    • Hey Theresa! Unfortunately, the AIRx Odor Filters are limited to 1″ thick filters. We offer MERV 8 and MERV 11 varieties for our 4″ pleated filters though. Hope this helps answer your question.

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