What is a Furnace Filter Efficiency or MERV Rating?
What is MERV? MERV or Minimum Efficiency Reporting Value is the airborne particulate filtering efficiency rating of an air/furnace filter/air cleaning device that is arrived at through an efficiency evaluation process by applying the ASHRAE Standard 52.2 Test procedure. The filtering capability is determined through a comparative count of airborne particulate matter by taking measurements both upstream and downstream of the filter being tested. The MERV rating is based upon the worst case performance of the filter recorded through six different stages of dust loading with 0.3 to 10 micron size particles to assure the best performance over the life of the air filter.
