The type and maintenance of air filters in your Twin Cities area home’s HVAC system can have a big impact on the quality of your indoor air, as well as heating and cooling performance. Selecting an appropriate air filter type, ensuring that it has been properly sized and fitted, and keeping it well maintained (either through routine maintenance or regular replacement) will improve your indoor air quality, while also improving your HVAC system’s longevity, performance and operating efficiency.
When shopping for a new air filter, you may notice that each carries a (Minimum Efficiency Reporting Value) MERV rating, a graduated scale from one to 20 that rates filters according to how effective they are at capturing different sized ai
rborne particles. The larger the value, the better the air filter is at capturing smaller particles. If the MERV rating isn’t on the packaging, look for other information on the packaging that indicates what type and size of particulates the filter removes.
Understanding MERV Ratings
Air filters with a MERV rating of 17 to 20 are known as true high-efficiency particulate absorption (HEPA) filters, which have been tested for removing a minimum of 99.7 percent of all particles that are .3 microns or bigger. These filters are used in medical facilities and similar industries where the cleanest of rooms is critical. When used in the home, they’re usually found in stand-alone air cleaners or HVAC systems that have been modified to use them.
Most new furnaces come with filters carrying MERV ratings of four or lower. These low-efficiency filters can only block 70 to 80 percent of all airborne particles that are 10 microns or larger. While this prevents larger dust and dirt from entering HVAC equipment and infiltrating a home’s indoor air, these filters are not capable of capturing the smaller pollen and dust that can significantly reduce your indoor air quality.
The ideal efficiency for homes is a mid-efficiency air filter with a MERV rating between seven and 12. While they do a good job of cleaning your indoor air, they have less chance of preventing impeded system airflow, something you’ll need in order to keep your system operating smoothly and efficiently.
To learn more about air filters, please contact Marsh Heating & Air Conditioning today.
Our goal is to help educate our customers in Minneapolis-St. Paul, Minnesota about energy and home comfort issues (specific to HVAC systems). For more information about air filters and other HVAC topics, download our free Home Comfort Resource guide.
Image courtesy of Shutterstock