Air filters are a vital part of our home’s indoor air quality and how well our HVAC system functions. Over the last decade, the technology behind air filters have improved and homeowners have several options to choose from. Now, everyone knows (or should know) that air filters are supposed to be changed at least every 1 to 3 months; the more your system runs, the more frequent you may have to change it. However, when it is time to change your air filter, what is the best type of filter that you should use? To answer that, we will discuss the available air filter options on the market and how they are “graded”.
MERV stands for Minimum Efficiency Reporting Value and are the grading system of air filters. Air filters are typically given a MERV rating or number between 1 and 16. The higher the number, the more airborne particles the air filer is able to trap. Higher MERV rated filters are capable of trapping smaller airborne particles including bacteria and allergens, while lower rated filters only trap larger airborne particles like dust and pet hair. MERV ratings are applied to most types of air filters available for purchase in retail stores.
Types of Air Filters Available
- Fiberglass Filter – These are a cheap throwaway air filters that is one of the most common types available. The fiberglass is layered over each other and enclosed in a metal grating to keep the rectangular form. It is made in a variety of sizes to fit just about any sized air conditioning system.
- Polyester and Pleated Filter – The second most common type of filter used is the pleated polyester filters. Made in a similar design to the fiberglass filters with metal grating to hold the design, the polyester filter is layered and then pleated in order to capture and hold onto smaller airborne particles than the fiberglass is capable of.
- HEPA Filter – HEPA, or High Efficiency Particulate Arrestance, level filters are filters that meet a very stringent standard set by the U.S. Department of Energy. They are typically comprised of fiberglass fibers that are layered and arranged so that it is capable of capturing 99.97% of all particles sized 0.3 microns or larger. For size comparison, a human blood cell is roughly 5 microns across and a human hair is typically 75 microns across.
- Reusable Filter – There are many designs and styles of reusable air filters, but the best kind are those labeled as Electrostatic Air Filters. They are 10 times more efficient than your standard throwaway air filters and can be washed (or hosed down) and used again once dry. These filters use static electricity to capture 94% of the air particles that pass through it. They can be expensive but if you routinely wash it out every 3 months, it should last you up to 5 years.