Understanding MERV
The ASHRAE Standard 52.2 ANSI/ASHRAE Standard 52.2 features many improvements over the 52.1 standard. In 2009 ANSI/ASHRAE 52.1 “Dust Spot” efficiency testing was removed from the standards while two other parts of the 52.1 Standard were adopted into the 52.2 Standard, allowing for the 52.1 to be retired. The two parts of 52.1 adopted by 52.2 are “Arrestance …