What Exactly is a MERV Rating?

merv rating

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The filters you use in your HVAC system improve the indoor air quality of your home. If you let your air conditioner filters become clogged with dust and dirt, it increases the work the fan has to do.

This decreases the efficiency and performance of your HVAC system.

Your fan works harder depending on how clean the filter is and its Minimum Efficiency Reporting Values (MERV). Do you know the MERV rating of your air filters? The rating of your air filter is important because it impacts the effectiveness of the filter and the air quality in your home.

Read more about MERV ratings for filters, how often to change the air filter, and everything else you need to know below.

What Are MERV Ratings?

MERV is an acronym for Minimum Efficiency Reporting Value and is the industry standard to evaluate the effectiveness of air filters. MERV rating is a simple way to determine how well your filter will catch pet dander, dust particles, air pollutants, allergens and other particles in your home’s air.

The values of the ratings depend on the size of the holes in the air filter. The size of the gaps between fibers lets you know the size of the particles that can escape into your home.

What Are the MERV Rating Scales?

MERV rating scales range from 1 to 16. One is the least efficient and 16 is the most effective. If you’re wondering, “Which MERV rating should I use?” just remember that the lower the MERV rating, the bigger the holes in the filter that allow particles through.

The United States Environmental Protection Agency has a MERV rating chart for air filters. The information can help you decide which one is the best for your home.

MERV 1-4

Air filters with a MERV rating of 1 to 4 provide minimal filtration. These filters capture less than 20 percent of 3.0 to 10.0-micron particles. You have to replace them frequently.

These filters collect contaminants, such as pollen, carpet fibers, dust mites, and cockroach debris. You usually find these filters in residential window air conditioning units.

MERV 5-8

Air filters with MERV ratings of 5 to 8 capture from 50 to 85 percent of 3.0 to 10.0-micron particles. They collect mold spores, animal dander, dust mites, hair spray, fabric and dusting spray. These filters are commonly used in homes, businesses and hospital laboratories.

MERV 9-12

Air filters with MERV ratings of 9 to 12 are usually the most efficient air filters used in homes. They can capture 50 percent of particles as small as 1.0 microns and 65 to 90 percent of 3.0 to 10.0-micron particles.

They capture bacteria pathogens, mineral dust from humidifiers, lead particles, flour dust, auto emission pollutants and sneeze droplets. These filters are used in homes, business and hospital laboratories.

MERV 13-16

Air filters with MERV 13 to 16 ratings can trap up to 75 percent of 0.3-micron particles and 98 percent or more of particles of 3.0 microns or greater.

They collect bacteria, sneeze droplets, cooking oil, cigar, and cigarette smoke, pest control dust, cosmetic powder and paint coloring pigments. They’re used in home, businesses and hospital settings.

Which Air Filter Should You Choose?

While it’s important to choose an effective filter, it’s also important to remember that it’s not always about the highest MERV rated filter. When the spaces between the fibers are small, it causes resistance to the airflow in your air conditioning system and furnace.

If your HVAC system wasn’t made to handle MERV 13 filters or higher, it can lead to malfunctions in the system. So, it’s important to choose the highest MERV rating that your system can handle. If you’re not sure about what you should use, ask an HVAC professional or consult your owner’s manual for the information.

Most residential furnaces and air conditioning units use MERV 8 filters up to MERV 12 filters. If someone in your family has allergies, asthma or respiratory problems, bump up the to a MERV 13 filter if your system can handle it.

MERV 14, 15 and 16 are usually used in medical offices where germs, medical conditions, and clean air are important to minimize health risks.

Tips on Purchasing and Changing HVAC Air Filters

If you’re purchasing your air filters from your local home improvement store, you could be making the air quality in your home worse. Did you know that many filters sold in home improvement stores usually have a MERV rating less than 7?

Also, before you purchase a filter check the fit. Filter size varies depending on your system. Check the dimensions of your old filter before choosing a new one. When you install the new filter, it shouldn’t have any gaps on any of the sides.

When you take out the old filter, make a note of the direction it faces. If you put the air filter in the wrong way, it will affect the efficiency of the filter. It could restrict the airflow in the unit.

Rather than purchasing the wrong filters or an inefficient filter for your air conditioning system, ask your HVAC company for the best options and MERV ratings for your system.

How Often Should You Change HVAC Air Filters?

For the best performance, change your filters every three to six months depending on your indoor air quality and how much you use your system. By changing your filters regularly, you can avoid costly repairs if your system is overworked from blocked filters.

Clogged filters also raise your energy bills each month as your system struggles to produce quality air. This can put a strain on components in your system causing them to wear down sooner than normal.

Keep Cool With Regular HVAC Maintenance and Clean Filters

Remember that regular HVAC maintenance and clean MERV rating filters are the best way to make sure your system is reliable and efficient for many years.

Transition periods are good times to have your HVAC maintenance schedules, such as between the heating and cooling seasons in the fall and spring.

Contact us for all your heating, air conditioning, and humidification needs. We can help you find the perfect air filter for your home to ensure your family has clean, high-quality air.

John Daner
John Daner

HVAC Technician with 12+ years experience in the field.

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