MERV stands for Minimum Efficiency Report Value and is an industry standard that measures the overall effectiveness of air filters. It is a standardized system created by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) and used by all manufacturers of air filters. Rating values range from 1 (lowest efficiency) to 20 (highest efficiency).In simple terms, it sets the minimum amount of particles a filter must capture to obtain a specific MERV rating. For example, if an air cleaner can capture at least 20% of E1 particles, 65% of E2, and 85% of E3 particles, it will get a MERV 11 rating.
It should also be noted that filters at the lower end of the MERV scale are not even tested for their efficiency in capturing E1 and E2 particles. E1, E2, and E3 particles are particle range sizes used in air filter tests to determine a MERV rating. E2 particles range in size from 1.0 to 3.0 microns. Typical E2 particles include pet dander and PM2.5 particles having a diameter of 2.5 microns or less. A filter with a MERV rating of around 10 to 12 is sufficient to remove most allergy-causing particles from the air in your home. Filters are rectangular in shape, so there will be a length, width, and thickness (usually 1 to 2″ for residential HVAC systems).Choosing the right MERV rating is an important decision in terms of total cost, air quality, and product durability.
A higher rating means the filter can trap smaller air particles. A filter with a MERV 13 rating will capture 90% or more of them at their worst. Most people will need to change their filters at least every 2 months. If you have pets in your home, you will probably need to change the air filter more often. However, a high MERV rating on an air filter generally means that the filter is thicker and your HVAC system will have to work harder to circulate air throughout the house. Filters with a MERV 6 rating are more affordable and will provide the bare minimum for a home without furry pets.
When an AC fan is started, the movement of air can cause the filter to crash into the interior of the unit if it is not properly secured. It is recommended that you check your air filters once a month to see if they are dirty enough to need to be replaced. All air filters require periodic cleaning and filter replacement to function properly. Follow manufacturer's recommendations for maintenance and replacement. In conclusion, choosing the right MERV rating for your home is essential for maintaining good indoor air quality while keeping energy costs low. A higher MERV rating means better filtration but also higher energy costs due to increased airflow resistance.