What is MERV? A MERV Rating? A MERV Filter?
MERV stands for Minimum Efficiency Reporting Value. This is a system used to check the efficiency of an air filter catching particles of varying sizes. MERV ratings are the filter’s effectiveness at filtering particles of different sizes. The higher the MERV rating, the more effective the air filtration capabilities of the filter.
In the 2019 Residential Building Energy-Efficiency Standards you will find information on the MERV Rating in Table 150.0-A. The code states in (m) Air-Distribution and Ventilation System Ducts, Plenums, and Fans – Section 12C: “The system shall be provided with air filters having a designated efficiency equal to or greater than MERV 13 when tested by ASHRAE Standard 52.2, or a particle size efficiency rating equal to or greater than 50 percent in the 0.30-1.0 μm range and equal to or greater than 85 percent in the 1.0-3.0 μm range when tested by AHRI Standard 680.”
Accordingly, to use a 1″ filter, you must size per table equation 150.0-A AND must have pressure drop of no more than 0.1” w.c. The standard MERV 13 filter has a default size of 2″ thick. There are some companies developing filters with a smaller thickness.
Want to know more?
In brief, take a look at this article that the National Association of Home Building wrote on MERV Ratings and Air Filtration.
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