What is MERV Rating on Air Filters?

MERV stands for “Minimum Efficiency Reporting Value” and is a rating system used to measure the effectiveness of air filters in your HVAC system. MERV ratings range from 1 to 20, with higher numbers indicating a higher level of filtration. A MERV rating of 8 or above is recommended for most residential applications, while higher-rated filters are typically used in commercial or industrial settings.

MERV filters can capture particles such as pollen, dust mites, pet dander, and other airborne pollutants. However, it is important to note that the higher the MERV rating, the more restrictive the airflow can be, which can impact the efficiency of heating and cooling systems. For this reason, it’s crucial to choose the right filter for the application to ensure proper airflow and efficient operation of HVAC systems.

To help you make the right choice for your Tucson home, let’s explore:

Air filters play a crucial role in maintaining indoor air quality by removing harmful pollutants, allergens, and irritants from the air we breathe. However, not all air filters are created equal, and selecting the right filter for your home’s HVAC system is essential. This is where MERV air filter ratings come in.

Developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), MERV ratings are used to measure the effectiveness of air filters. Specifically, their capacity to trap particulates between 0.3 and 10 µm (microns), including things like pollen, dust mites, pet dander, mold spores, and bacteria.

The higher the MERV rating, the more efficient the filter is at removing airborne pollutants. For example, a filter with a MERV rating of 8 will capture at least 70% of particles between 3.0 and 10 microns in size, while a filter with a MERV rating of 11 will capture at least 85% of particles in that size range.

The MERV rating system ranges from 1 to 20, with higher numbers indicating a higher level of filtration efficiency.

Air filters with a MERV rating of 1-4 are typically found in window air conditioner units, home furnaces, and small commercial buildings. They can filter out larger particles such as lint and general house dust.

MERV 5-8 filters are an excellent choice for homeowners and businesses that want to improve indoor air quality and reduce the risk of respiratory illness. They can filter out pollen, dust mites, carpet fibers, dust, and other typical household particles.

MERV 9-12 air filters work well in places that require better-than-average air quality, such as medical laboratories, nursing homes, and healthcare facilities. Compared to lower-rated filters, MERV 9-12 filters can filter bacteria, mold spores, and other microscopic contaminants to help reduce the risk of respiratory illness and allergies.

MERV air filters rated between 13 and 16 offer superior air filtration ability necessary in surgery rooms, hospitals, nursing homes, and medical laboratories. Particulates controlled by MERV 13-16 air filters include bacteria, respiratory particles released by sneezes and coughs, pet dander, vehicle emissions, and other particles as small as 0.3 to one micron in size.

Closely monitored environments such as pharmaceutical manufacturing facilities, operating rooms, and areas exposed to carcinogenic or radioactive contamination use the highest MERV air filters. Capable of filtering out particulates less than 0.3 microns, MERV 17-20 filters prevent viruses, gaseous contaminants, and suspended atmospheric dust from corrupting the air.

Standing for “High Efficiency Particulate Air,” HEPA filters are the highest-rated air filters available and are designed to capture at least 99.97% of airborne particles that are 0.3 microns or larger. This includes particles like bacteria, mold spores, and viruses. HEPA filters are commonly used in hospitals, laboratories, and other environments where the highest level of air quality is required.

HEPA filters are more efficient than high-MERV filters at capturing the smallest particles, but they also have a higher resistance to airflow. This means that HVAC systems may need to be designed or adjusted to accommodate HEPA filters. Additionally, HEPA filters can be more expensive than high-MERV filters and may need to be replaced more frequently, depending on the level of air pollution in the environment.

Most HVAC systems or residential furnaces can use MERV filters that are rated 13 and under. However, since the majority of HVAC system guides do not offer filter recommendations, we recommend speaking with a trusted HVAC company for air quality advice.

By having a knowledgeable professional review your unique circumstances (e.g. the type of heating and cooling system you have, your air quality concerns, etc.) they can recommend the best air filters for your home and budget. They’ll also review the amount of maintenance required, as MERV air filters will need to be replaced ongoing.