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Cleveland HVAC Blog

Making Sense of Choosing the Right Air Filter—Just Ask MERV!

Posted by Paul Wadsworth on Mon, May 07, 2012 @ 01:18 PM

In order to learn how efficient an air filter is, just ask MERV—the MERV rating, that is! MERV is the Minimum Efficiency Reporting Value, telling you what size particles a filter can effectively remove. Your indoor air quality is directly related to the quality of your air filter, so choosing the right MERV-rated filter can improve your comfort, savings and health.

air filter merv ratingsThe MERV scale was developed by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE). Most residential MERV-rated filters fall on a scale between 1 and 16 (with higher being more efficient), but some go as  high as 20.

It’s important to look at MERV ratings, because many filters that come with HVAC equipment are very low efficiency, MERV 4 or less, and are primarily intended to protect the equipment itself. Without a filter, large particles build up in the system, reducing efficiency and increasing friction. Unfortunately, this low rating isn’t enough to protect your indoor air quality.

ASHRAE itself recommends using a MERV 6, and the U.S. Department of Energy recommends at least a MERV 13. Performance of MERV-rated filters varies:

  • MERV  1 to 4 – captures less than 20 percent of particles from 3 to 10 microns (large particles).

  • MERV 5 to 7 – captures between 20 and 69 percent of large particles.

  • MERV 8 to 10 – captures about 85 percent of large particles, and about 50 percent of particles as small as 1.0 to 3.0 microns.

  • MERV 11 to 16 – captures over 90 percent of the largest particles, and between 70 and 90 percent of the smallest particles, from 1.0 to 3.0 microns.

  • MERV 17 to 20 – captures the smallest particles, smaller than 0.3 microns.

Obviously, MERV-rated filters of 16 or higher are the most effective at trapping the tiniest pollutants, but not every filter is right for every home. More efficient air filters can restrict airflow and that can damage equipment and reduce system effectiveness.  So it’s important to choose one that won’t impede the performance of your HVAC system and yet filter the air effectively.

If you’re choosing a new MERV-rated filter, give P.K. Wadsworth Heating & Cooling a call with any questions. Helping Greater Cleveland area homeowners improve their comfort is what we do best.

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Photo Credit

Paul WadsworthPaul Wadsworth is the President and Owner of P.K. Wadsworth Heating and Cooling. For 37 years, Paul has been providing heating and cooling services to the Greater Cleveland area. P.K. Wadsworth has been a trusted Cleveland HVAC service company for 75 years. The company understand the area's construction and local heating and air conditioning needs. Paul has an MBA from the University of Michigan and a B.S., Industrial Engineering from Purdue University. He's been President of the Cleveland Air Conditioning Contractors of America and a founding member of the local chapter. Paul was born and raised in Cleveland and has been active in the local community. He resides in Cleveland, Ohio with his wife and two sons.

The opinions and statements contained in this article are for general informational purposes only and are not instructions. Only trained, licensed and experienced personnel should attempt installation/repair. The author assumes no liability for the opinions/statements made in this article. Any individual attempting a repair or installation based on this article does so at their own risk of loss.

Topics: merv ratings, air filters, hvac equipment, indoor air quality, MERV-Rated Filter

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