MERV Rating Explanation
MERV stands for Minimum Efficiency Rating Value. This is an industry standard rating system. It allows you to compare filters made by different manufacturers. A MERV rating is a numerical value ranging from 1 (lowest efficiency) to 20 (highest efficiency). This rating system tells the consumer how well the filter captures and holds dirt. This is based on dust of a specified size range. The chart below shows the MERV ratings. It shows corresponding particle size ranges. It also shows air filter efficiency levels. Efficiency is measured by the percentage of particles captured.
The MERV air filter efficiency rating system was developed by the ASHRAE. ASHRAE stands for the American Society of Heating, Refrigerating, and Air-Conditioning Engineers. The rating system is referred to as ASHRAE Standard 52.2-2007. This method tests Air-Cleaning Devices for Removal Efficiency. The test is based on particle size. Standard 52.2 establishes a testing protocol. It ensures reliable and consistent testing of air filter performance. The performance is based on particles that are 0.3-10 micron in diameter. This Standard has lead to the creation of the minimum efficiency rating value, or MERV. This guideline determines a filters performance by particle size. The filter is assigned a value based on the test. This value is derived from the lowest efficiency for the filter. In many cases this is when the filter is first installed.
Higher= More Filtration
Generally, the higher the MERV (M), the better the filter performance in removing smaller particle sizes. M values 1 through 4 are designed to remove large particles. These filters are used primarily to protect equipment. They are used in light industrial and residential applications. For these values, the average particle size efficiency from 3 to 10 micron is less than 20%. Average arrestance is a measure of a filters ability to remove coarse particulate. It is used to determine MERV 1 through 4. A lint trap in a dryer is about MERV 2
M Value 5 through 16 air filters remove finer dust particles. These air filters are used to protect people or products from airborne contaminants. These particles could hurt health and productivity. The average particle size efficiency has three ranges. E1 is 0.3 to 1 micron. The E2 range is 1 to 3 micron. E3 goes from 3 to 10 micron. These 3 ranges determines the MERV Rating for these air cleaning products.
At LakeAir, we recommend MERV 10 filters as our better air filter. These filters do a good job at removing harmful indoor air pollution. They offer good airflow. M 10 filters are easy on air blowers and fans. We recommend MERV 11 filters as our “best air filter.” These air filters are great for people with pets. They remove pet dander and most allergy causing air particles. These include mold, smoke and pollen. Our activated carbon filters help remove VOCs and odors not covered by ASHREA tests. We do not recommend M 12 or higher 13 filters. They may negatively affect certain HVAC systems. These filters can cause restricted airflow. The blowers in HVAC units rely on a good air supply to keep them cool.
The following chart describes each MERV value in the rating system:
MERV Ratings explained
MERV Rating Explanation in 5 stages
Typical applications for the major MERV value ranges are:
M 1 – 4
- Minimum filtration, used almost exclusively in residential buildings
M 5 – 8
- Most commercial applications and better residential buildings
M 9 – 12
- Superior residential buildings and better commercial buildings
M 13 – 16
- Hospital inpatient and general surgery; found in superior commercial buildings
M 17 – 20
- Clean rooms and pharmaceutical manufacturing