What is the MERV Rating on Air Filters and How to Choose the Right One

The Minimum Efficiency Report Value (MERV) rating for an air filter measures how effectively the filter prevents dust and other contaminants from passing through the filter and reaching the air stream. Filters with higher MERV values trap small particles more effectively than filters with lower MERV scores. An official website of the United States government, Official websites use.gov, belongs to an official government organization in the United States. The Minimum Efficiency Report, or MERV, values indicate the ability of a filter to capture particles larger than 0.3 to 10 microns (µm).

All air purifiers require periodic cleaning and filter replacement to work properly. Follow the manufacturer's recommendations for maintenance and replacement. MERV stands for Minimum Efficiency Report Value. MERV ratings are a classification system designed by ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers) to report on the effectiveness of air filters. Not all filters are made the same way; the higher the number, the better the filter.

However, your HVAC system may not handle a larger number. MERV 13 air filters even provide additional filtration power against fine particles compared to MERV 11 filters. You might think that an air filter with higher MERV ratings would be more beneficial, but in some cases, it's not. Choosing the right MERV rating for your oven filter has a big impact on indoor air quality, the air conditioning system and, most importantly, the well-being of your family. A higher MERV rating may mean slightly more restricted airflow; however, most current HVAC systems are capable of handling a MERV 11 air filter without increasing system voltage. Unlike other scales, which emphasized the need to increase the amount of particles that pass through an air filter, the MERV was designed to offer a balance between particle filtering and energy efficiency.

While MERV ratings reflect a filter's ability to trap microscopic and macroscopic particles, MPR ratings only rate a filter based on its ability to remove particles from 0.3 to 1 micron. In standard cases, a MERV 8 air filter is considered a more than adequate option, but it may not be sufficient when it comes to combating increased outdoor air pollution, pet fur and dander, or triggers for asthma and allergies. Selecting the correct MERV rating for your air filter is a balancing act between the capabilities of your HVAC system and the indoor air quality you want to achieve. Newer units should not have airflow problems with higher MERV ratings, although older models may work more with a MERV 13 filter installed than when they originally had a MERV 6 filter in the air intake. If your filter has a high MERV index, you know that it's very effective in preventing things like pollen, bacteria and pet dander from circulating throughout the house; however, it can be too effective in preventing air from circulating, which is a bad thing.