What is a MERV?
Minimum Efficiency Reporting Value, or MERV, is a scale that rates the effectiveness of air filters. Created by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) in 1987, air filter MERV ratings relate to the relative effectiveness of the filters they’re assigned to.
How Do MERV Ratings Work?
Filters are rated on two different performance factors as measured by testing both the upstream and downstream airflows of a given air-cleaning appliance. The first factor evaluated is how effective a filter is in removing large (greater than 1 micron in size) particles like pollen, pet dander, and byproducts from dust mites. The other factor is efficiency in filtering out particles less than 1 micron in size, such as smoke from cooking or tobacco, household dusts, bacteria, viruses, and even benzene gas. (As a matter of perspective, the eye of a needle (depending on the type of needle, of course) is somewhere in the 500-200 micron range.)
What is the Best MERV Rating for Your Needs?
Given that some 98 percent of all indoor air particles are under one micron in size, a filter’s ability to remove these minute yet potentially harmful specks is especially important when it will be used to improve the quality of indoor air.
Filters are rated from 1 to 20; the higher the rating, the better that filter works. For home or commercial use, ratings from MERV 8 to MERV 13 are suitable. This includes restaurant use as well; if you have a cigar lounge or otherwise need to filter out a lot of tobacco smoke, you should aim for the high end of the 8-13 range or perhaps even a 14.
More clinical settings where cleanliness is of utmost importance, such as in a hospital, might require filters with a MERV rating of 14 or higher, but anything past a 17 is really only necessary if it’s being used in a clean room or other demanding scientific or medical situation. Conversely, filters with a rating of 7 or less are generally considered to be substandard.
Should I Buy a MERV 20 Filter? (Hint: Probably Not)
While it might be tempting to think that using the highest rated filter available (in other words a MERV 20) is the best decision regardless of the situation, the more dense a filter is – and therefore the more effective it is at trapping the smallest particles – the more taxing it is to your air filtration system.
The harder your system is forced to work, the more maintenance it will need, the quicker it will ultimately wear out, and the more energy it will need in order to run. Choose the filter that is ideal for your restaurant or other facility – no more, no less. The higher your filter’s rating the more frequently you should be changing it out to avoid airflow becoming restricted by accumulated dust and other debris.
Have questions about MERV rating standards or need help selecting the most effective filter for your ventilation system? Visit HoodFilters.com or call 877.394.9731 to speak with a customer service specialist.