About Merv Filter Ratings

What Is MERV?
MERV stands for Minimum Efficiency Reporting Value. Or in English, “how effective is your air filter?” MERV ratings range from 1-16. The higher the MERV rating on a filter, the fewer dust particles and other contaminants can pass through it. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) designed the MERV scale to represent a filter’s worst possible performance at removing particles .3 to 10 microns in size (that’s really small!).

Some of the common particles that filters are tested for include pollen, dust mites, textile and carpet fibers, mold spores, dust, pet dander, bacteria and tobacco smoke. Most residential systems can adequately remove airborne contaminants with a filter rated MERV 7-12. MERV 13-16 is typically found in hospital and general surgery settings.

Higher Is Not Better
You might think that a higher MERV rating would automatically be better, but it’s not. The higher the MERV rating, the smaller the pores are for air to flow through an HVAC filter. This can create more resistance in airflow than a system is designed to manage, thus making it inefficient. Reducing the air flow in your system can actually worsen the air quality in your home and put a damaging amount of pressure on the fan of your furnace or AC system. So it is worth doing some research. Find out what the highest MERV rated filter is that still allows for maximum airflow in your system.

Change Filters Often
Filters with higher MERV ratings need to be changed more frequently (at least every three months) to avoid restricted airflow that can cause your system to work inefficiently or possibly even damage it.

How to Correctly Measure Your Air Filter Size