When shopping for an air filter to use in your heating, ventilation and cooling (HVAC) system, you should consider the minimum efficiency reporting value (MERV) rating. Whether pleated or fiberglass, air filters typically feature a MERV rating. You can use it to determine how much particulate matter an air filter remove will remove.
What Are MERV Ratings
MERV ratings reflect the minimum size of the particulate matter that an air filter can remove. All air filters are designed to remove particulate matter. As air flows through them, airborne particulate matter will accumulate on the surface of an air filter. Some air filters, however, are capable of removing smaller pieces of particulate matter than others.
The MERV formula was developed by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) in 1987. It uses a scale ranging from 1 to 16. The higher the MERV value, the smaller the particulate matter an air filter can remove. Air filters with a MERV rating of 16 can remove particulate matter as small as 1 to 0.3 microns.
What’s a Good MERV Rating?
You might be wondering what MERV rating to choose when shopping for an air filter. Air filters with a MERV rating of 1 to 4 offer the least amount of protection from airborne pollutants. They can typically remove pollen, dust and small fibers from carpet or upholstery, but many other forms of airborne debris will pass straight through them.
You can usually find air filters with a MERV rating of 1 to 4 on window air conditioning units. For a central HVAC system, however, you should choose an air filter with a higher MERV rating.
A MERV rating of 6 to 10 is more common for central HVAC air filters. With this range, air filters can remove smaller particulate matter. They can still remove all of the particulate matter as previously mentioned, but many of them can remove mold spores, dander and other ultra-small pieces of debris as well.
If you or someone in your family suffers from respiratory allergies, you may want to choose an air filter with an even higher MERV rating. Respiratory allergies are often triggered by small airborne pollutants. Something as simple as switching to an air filter with a higher MERV rating may offer relief.
Keep in mind that a high MERV rating can have a negative impact on airflow. It will restrict airflow through your HVAC system, which can lead to other problems. Therefore, you may want to avoid choosing an air filter with a MERV rating of 14 or higher.
