Think a High-Efficiency Air Filter Doesn't Make a Difference? Think Again

by Greg Leisgang on August 20, 2013

Posted in: Indoor Air Quality

air filter-Butler County, OhioA critically important factor affecting the indoor air quality of your greater Cincinnati area home is the selection and maintenance of your HVAC system's air filter. Choosing the most appropriate type of air filter, ensuring that it's sized and fitted correctly and maintaining it at regular intervals will not only improve your indoor air quality, but also your HVAC system performance, longevity and operating efficiency.

Each air filter sold carries a specific minimum efficiency reporting value, or MERV rating. This is a graduated scale running from 1 to 20 that rates filters according to their ability and efficiency at capturing various sized airborne particulates. Larger numbers indicate the capability of trapping smaller-sized particles.

MERV ratings, broken down

MERV 17 to 20 filters, also known as HEPA filters, are able to remove a minimum of 99.97 percent of all particles 0.3 microns or larger. HEPA filtration is used primarily in medical facilities or industries where clean rooms are required. They aren't typically recommended for use in residential HVAC systems because of their inherent airflow restriction, though they are used in some vacuum cleaners and air cleaning or purifying equipment.

Many new-home HVAC systems come with an air filter carrying a MERV of 4 or lower. These are able to block 70 to 80 percent of airborne particles 10 microns or larger. While these are generally effective at capturing dirt and dust that could otherwise harm your HVAC equipment, they do little to improve the quality of the air you breathe at home. These inexpensive fiberglass filters must be replaced with a higher MERV-rated filter to significantly improve your indoor air quality level.

For most homes, filters with MERV ratings of 8 through 12 are ideal. MERV 9 through 12 filters are considered high-efficiency, capable of filtering up to 95 percent of all particles between one and three microns or larger. Filters must be precisely fitted so as not to allow air to bypass them. They should be checked monthly and replaced or cleaned when dirty.

For more information about MERV, air filters or any other home comfort concerns, contact the pros at JonLe Heating & Cooling. We have more than 50 years of experience providing expert HVAC services to Butler County and the greater Cincinnati area.

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