What is a filter MERV rating?
[back to top] The job of the filter is to capture particles. The better the filter is at capturing, the cleaner your air you breathe, and provide greater protection for your HVAC system. The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRE) conducts reliable and verifiable tests including a calculation of the average particle size efficiency (PSE) of filters. The results are used to determine the MERV (Minimum Efficiency Reporting Value) rating, which is expressed in ranges (1-4, 5-8, etc.), on a 20 point scale. The higher the number, the more effective the filter is in capturing small particles. The smaller the particle, the more difficult it is to capture. Most harmful particles are less than 5 microns in size and they are not visible in the air. It is the tiny particles that are inhaled. What MERV rating should I use? [back to top] At the bottom of the efficiency scale are the traditional 1-inch fiberglass or polyester filters. These inexpensive, disp
