What is MERV Rating?

What is MERV Rating?

The MERV rating on air filters is a number from 1-16 that was established to help consumers understand how good a particular air filter is at removing foreign airborne particles.

What are MERV ratings?

MERV is an acronym for Minimum Efficiency Reporting Values. This designation was derived by the American Society of Heating and Refrigerating and Air Conditioning Engineers, or ASHRAE, to help consumers compare the performance level of various air filters.

How do I find the MERV rating on filters.

There are two thicknesses for mechanical air filters that are used on most residential HVAC systems.
For both the 1” and 5” filters, MERV rating can typically be found on the narrow 1” or 5” edge of most residential filters. The MERV rating is also located on most filter packaging labels.

Highest and lowest MERV rating air filters

The MERV rating on air filters for residential HVAC systems range from 1-16. The higher the MERV rating, the smaller the particle it is able to trap and the better it is at removing them.
Click to see a detailed chart on Average Particle Size Efficiency in Microns.

5 benefits of a higher MERV rating on filters:

• Less Dust
• Less Pollen
• Less Mold
• Less Allergan
• Better Quality Air

What MERV rating should I use?

If minimizing pollens, allergens, molds or dust is a priority, you’ll want to pay closer attention to the MERV rating on air filters you choose.

Many older systems still use 1” filters for removing contaminants from your home. Determining what MERV rating is best if this is the case may be more difficult since higher MERV rated 1” filters can also be highly restrictive to good airflow. In these cases you’re sometimes better off choosing a filter with a lower MERV rating that can compensate for this restriction.

For most 5” filters, if money’s not the main concern, you’re better off getting a MERV 16 since it provides the best indoor air quality and also helps to protect the internal workings of the furnace and AC coil.

So What is a HEPA filter?

MERV vs HEPA

HEPA or“High Efficiency Particulate Air” is an acronym for a pleated type of mechanical air filter. It was established by the U.S. Department of Energy.

Theoretically a HEPA air filter can remove up to 99.97% of pollen, mold, bacteria, dust or any other airborne particle the size of 0.3 microns.

Any particles larger than this will get trapped at an even higher efficiency. For reference sake 45-50 microns is the average size of human hair. The human eye can generally not see anything that’s smaller than 40 micron

What MERV rating is best?

Now that you have a better understanding of MERV vs HEPA, deciding what MERV rating is best for you should be a far less daunting task.

HEPA filters are generally used in hospital settings and have the highest MERV ratings of between 17-20.

For additional Indoor Air Quality (IAQ) details, see the US Environmental Protection Agency (EPA).