Quick Guide to Air Conditioning Filter Types and Ratings
The air filter that you periodically change out on your central air conditioning (AC) system must be the correct type for your AC system in order for your home to be as cool as possible. Here’s a guide to the various types of air filters and air filter ratings:
Disposable Fiberglass Air Filters
Disposable air filters are composed of a sheet of fiberglass filtering material enclosed in cardboard. Disposable fiberglass filters are good at catching large particles up to 40 microns in size from the air. Fiberglass filters remove up to 10 percent of large air pollutants from the air. These are the cheapest filters available, so you can change them often.
Disposable Pleated Air Filters
Disposable pleated air filters are folded (pleated) sheets of filter material surrounded in a lightweight cardboard or other frame. The filter can be made of biodegradable material, including paper. Some of the better disposable filters may also have cells or fins incorporated into their designs. Disposable pleated filters help remove large particles from the air, but the filters also screen for smaller particles like mites and mold spores.
Disposable pleated filters can remove up to 45 percent of air pollutants in a residence depending on the number and size of the pleats. Filters with more pleats remove more particles from the air since more airflow occurs through the multiple pleats.
Both fiberglass and pleated disposable filters are available in high-efficiency versions that claim to remove up to 85 percent of pollutants in the home. Some high-efficiency filters are treated with anti-microbial agents to inhibit the growth of bacteria and mold.
Electrostatic Air Filters
Disposable electrostatic filters are made of fibers that are electronically charged. Both tiny and large particles are attracted to the surfaces of electrostatic filters.
Reusable electrostatic filters are permanent air filters. The fibers in reusable electrostatic filters are electrically charged just like the material in the disposable electrostatic filters. Reusable filters can be cleaned with a hose and placed back in use without having to purchase more filters in the future.
However, permanent electrostatic filters don’t remove as many small particles as disposable types of electrostatic air filters.
HEPA Air Filters
High-efficiency particulate air (HEPA) filters remove the most particles from household air. Up to 98 percent of air pollution is removed with some brands of HEPA filters.
Don’t place true HEPA air filters on your central AC unit without talking with your Mauzy AC professional first. A HEPA filter restricts the air flow in the AC system, and most standard central AC systems don’t provide enough air pressure to overcome the huge loss of air flow.
HEPA filters should only be used in approved applications. A separate HEPA filtration system is needed to use HEPA-type air filters in your home. A Mauzy HVAC pro can explain how a HEPA filtration system works if you want extra clean air in your home or suggest other alternatives.
MERV Air Filter Ratings
All types of AC air filters are rated with a minimum efficiency reporting value (MERV). The MERV scale ranges between 1 and 13 to help you gauge the best choice of air filter for your home.
MERV ratings for various air filter types include:
• Fiberglass: 1 to 4
• Pleated: 10 to 13
• High-efficiency: 14 to 16
• HEPA: 17 to 20
Higher MERV ratings correspond to higher efficiencies at particle trapping. Experts recommend you purchase air filters with MERV ratings of at least six to ensure most large particles are removed from your AC system.
If you’ve changed the AC air filter and the cold air’s still dusty or not flowing right, contact Mauzy Heating, Air & Solar for a complete checkup of your AC system. We serve residential air conditioning customers throughout the San Diego, California, region.