How to Factor MERV Ratings into your Buying Decision
Air conditioner filters help your heating and cooling units run at peak efficiency while providing your home with clean, quality air. When you’re shopping for an air conditioner filter, you can use MERV ratings to help you narrow down your search to just the right filter.
What is a MERV rating?
MERV is an acronym that stands for “Minimum Efficiency Reporting Value”. Filters are assigned a Minimum Efficiency Reporting Value rating or MERV rating to indicate their performance level. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) designed this system by creating numbered ratings that range from one to 20. The higher the number, the smaller the particles the filter may be able to catch. A higher MERV rating also may indicate a longer-lasting filter. MERV ratings do not reveal the filter’s ability to trap gasses.
Lowest MERV ratings
Air conditioning filters rated between one and four typically are used to protect heating and cooling equipment from debris buildup on fan motors and cooling coils but not for producing quality indoor air, according to the U.S. Environmental Protection Agency. Filters with the lowest ratings can't trap smaller airborne particles as well as filters with higher MERV ratings. These particles may include but are not limited to pet dander, dust mites, bacteria, viruses and some mold spores. Filters with MERV ratings between one and four can be found in disposable or washable aluminum mesh varieties. Window air conditioner filters are available in MERV ratings one through four as well.
Basic Protection
A MERV rating of four offers basic protection and can be a budget-friendly option. Not a reusable air conditioner filter, these flat panel filters can cost less than higher rated filters may cost. They are available in multiple sizes and two different thicknesses. A basic filter will protect the HVAC unit coils from becoming coated with grime and dust, which can lower the efficiency of the HVAC system.
General Filtration
With a MERV rating of eight, pleated panel filters are more efficient than the lower rated flat panel filters. The pleated filter media features synthetic fibers that are thermally charged and bonded. These filters will resist microbial growth while catching dust, dirt, pollen, some mold spores and other particulates, helping to improve your home’s indoor air quality. This level of filter may help increase the life of secondary filters, thereby saving you money. It typically will last longer than a filter with a lower MERV rating as well.
Filtration for Pet Owners
Pet owners often battle fur on furniture, carpets and more. Pet dander can cause more allergy problems than flyaway fur can. Opting for an air conditioner filter with a higher MERV rating may help limit the amount of pet dander moving through your HVAC system and circulating throughout your home. A filter with a MERV 11 rating can remove more than 85 percent of particulates sized between three and ten microns.
Maximum Filtration
For anyone suffering regularly from allergies and/or asthma, investing in a filter with a MERV rating of 13 or higher may help significantly improve your indoor air quality. A custom air conditioner filter is not needed to reduce allergens such as pollen, dust mites, mold spores, pet dander and more. Look for a MERV rating of at least 13 to capture these allergens. Filters with a MERV 13 rating can last up to three months.
When shopping for any HVAC filters, always keep in mind the MERV ratings. The EPA states that filters rated between seven and 13 can be almost as effective in delivering clean, healthy air as a High-Efficiency Particulate Arresting (HEPA) filter.
