The main job of any air filter is to trap dust, pollen, pet dander, and other airborne particles in its fibers. This keeps the air you breathe, and your system’s evaporator coil, clean.
Higher-quality filters will trap more of those nasty particles, which is particularly important for people who suffer from allergies or respiratory conditions like asthma, but a higher MERV rating is no substitute for a clean, properly fitting air filter, and a higher MERV rating also means smaller holes, which can restrict airflow and damage your system.
The Minimum Efficiency Reporting Value (MERV) is designed to help you balance your Indoor Air Quality (IAQ) needs with your energy efficiency needs, so don’t overdo it...
The recommended MERV rating for home use is 8 to 13.
Keep in mind that, when an air filter becomes clogged, air will bypass the filter and contaminate the evaporator coil, thereby reducing the coil’s heat absorbing capacity. In other words, your HVAC system will have to work harder to cool your home, resulting in unnecessary wear and tear, and higher energy bills.