Replacing the air filter on your HVAC system regularly is an excellent way to help keep your system working efficiently and maximizing its lifespan. The primary purpose of the air filter is to protect the evaporator coil and other components from accumulating a layer of dust, dirt and debris. A dirty coil cannot transfer heat efficiently which causes the system to work harder to heat and cool your home. This translates into higher costs and more wear and tear on the system. In addition to protecting your HVAC system, the air filter can help improve indoor air quality. Replacing the air filter is an important part of any HVAC system maintenance program.
Air filters are available in different efficiency ratings called MERV which stands for Minimum Efficiency Reporting Value. The higher the MERV, the better the filter is at catching smaller airborne particles. The standard fiberglass air filters that are the original equipment on most HVAC systems typically have a MERV rating of about 1 to 4. These fiberglass filters do a good job of capturing large dust particles and pet hair, but are not effective at collecting smaller particles, pollen, and other airborne contaminants.
High efficiency pleated filters have MERV ratings from 8 to 12 and can capture much smaller particles including mold spores, pollen, dust mites, and pet dander. It is possible to have too much of a good thing with regard to MERV. Air filters with a very high MERV will reduce airflow through your system and reduce system efficiency, especially when they are dirty. They also clog very quickly and should be changed more frequently than standard air filters.
If you choose to go with a high efficiency filter, it may be a good idea to avoid the filters with the highest MERV rating unless you are certain that your system is designed to operate efficiently with the reduced air flow. A pleated filter with a more modest efficiency rating will do a much better job of protecting your system and reducing airborne contaminates than standard fiberglass filters while having a minimal effect on air flow.
