Air filters are an important part of your cooling and heating system. They protect your HVAC equipment from build-up of dust and other particles, and they can remove potentially harmful pollutants from your indoor air.
But not all air filters are created equal. They come in various forms made of various materials and achieve various levels of effectiveness. The filter you select will help determine how well your HVAC system functions and how clean your indoor air remains.
The first thing to know: When you’re shopping for a filter, look for its MERV rating. The Minimum Efficiency Reporting Value rates the effectiveness of air filters on a scale of 1 to 20, with 20 being the most effective.
There are two main kinds of air filter: mechanical and electronic. Both can be installed in your HVAC equipment or used in portable units.
Electronic filters use “electrostatic attraction” to trap charged particles. They don’t, however, remove gases or odors. They also can produce ozone — a concern for some homeowners.
Mechanical air filters come in two types: panel, or flat; and pleated, or extended surface.
- Panel filters are usually made from glass fibers, animal hair, vegetable fibers or synthetic fibers. The material is coated in a substance that causes particles in the air to stick to the material as the air passes through. Other panel filters are made of material with a permanent electrostatic charge, which makes them better at capturing smaller particles.
- Pleated filters are a step up, able to trap smaller particles than panel filters. Pleated filters use materials such as fiber mats, glass fibers, synthetic fibers, cellulose fibers and wool felt to catch particles. High Efficiency Particulate Air (HEPA) filters are a type of pleated filter. These have high MERV ratings, but not all HVAC equipment has the airflow capacity to accommodate them. Check your owner’s manual if you’re considering a HEPA filter.
Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems). For more information about air filters and other HVAC topics, click here to download our free Home Comfort Resource guide.