There are many options when it comes to choosing air filters for your AC system. There are your cheap and basic fiberglass filters. There are more expensive options that provide superior filtering of air born particles and do not need to be replaced as often. Although it may be easy to assume that the more expensive filters are the best way to go, there are a few things to consider.

 

Filters are categorized by their MERV rating. MERV stands for “minimum efficiency reporting value”. The basic fiberglass filter typically has a MERV rating of 3 to 4. Higher end filters for home use will go up to 12. Filters that would be used for hospital operating rooms or cleans rooms where electronics are manufactured will have a MERV rating of 16 to 20. The higher the MERV rating is, the more effective the filter is at removing particles from the air.

 

The main purpose of the air filter isn't for improving indoor air quality. It is there to prevent dirt from clogging up the AC system and allow it to work as it should. Higher MERV rated filters will do a good job at filtering the air as well as making your system work harder. The thicker filter will do a better job at preventing particles from moving through it, but it will also make it harder for air to move through.

 

A pleated MERV 6 filter will give better filtration than a basic fiberglass filter while maintaining good air flow to your system. Pleated filters are folded like an accordion and provide more surface area for air to flow through, making them ideal for filters with MERV ratings above that of the basic fiberglass filters.

 

If superior indoor air quality is a priority, the best option is to go with a media filter. Media filters are pleated filters that are much thicker than the typical 1” filter. Media filters are usually 4” thick. This allows much more folded filter material to fit inside and provide more surface area for air flow. The increased surface area makes it possible to have a high MERV rated filter without extra stress on your system. In addition to the improved air quality, media filters do not need to be replaced as often as 1” filters.

 

Media filters require a cabinet that can house the larger filter. For new systems, it is highly recommended to install one. For existing systems, it depends on how your existing AC system is setup. It may be possible to retrofit a media filter cabinet.