The minimum efficiency reporting value or MERV rating, is used to rate the effectiveness of air filters. It was designed by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) in 1987.
The MERV rating represents worst case performance when removing particles that range from 0.3 to 10 microns, which are sizes we can't even see. These particles include dust, pet dander, pollen, dust mites, carpet and textile (clothes) fibers, mold spores, bacteria and smoke.
Picking the Right MERV Rating
The scale for MERV ratings goes from 1 to 16, with higher ratings indicating a higher percentage of particles captured. At the high end, a filter rated at 15 will capture 95% of particles.
But … a higher rating isn't always better. The higher the MERV rating, the smaller the pores are and less air will flow through your the filter. This resistance in airflow can make your furnace or air conditioning system run longer, which will increase your operating costs. So you want to do some research to find the highest MERV rating that will let your system run efficiently.
Typical filter ratings used are:
- MERV ratings from 7 to 12, are used for homes.
- MERV ratings of 13 to 16 are most often used in hospitals and sensitive manufacturing environments.
When Should You Change Your Filters?
Now that you understand how air flow affects the efficiency of your heating and cooling systems, you should recognize that a dirty filter will also restrict air flow. So the trade-off is paying to replace your air filters to reduce your heating/cooling bills, or face higher utility bills.
You'll need to do some research to determine the ideal MERV rating for your HVAC system. Once you've done this, write down your rating and filter size on a mailing label, and stick it on the filter frame where it's easy to find.
Now the real challenge is remembering when to change your filter(s), and buying them. A great solution I've found to make this easy, is FilterSnap.com. You simply order the:
- Filter size which varies quite a bit (mine are 20 x 30 x 1).
- MERV rating (8, 11 or 13) you want.
- Schedule for changing your filters, e.g. I want to change mine once a quarter.
FilterSnap will ship your filters (I have 2 systems, so 2 filters) when it's time to install them, which is the best reminder because it's automatic! Ordering is easy so isn't it time to take control of your home's air quality?
Note: I received one filter to review, and all information on this website is based on the knowledge of the author. In some cases, the author will get an affiliate commission for new customers who click on a product link. It never affects your cost, and it's how people get paid for the time they invest in sharing information like this.