When you are looking at air filters for your home, you’ll want to know MERV, an acronym that stands for Minimum Efficiency Reporting Value. In other, easier-to-understand words, MERV tells you how well an air filter actually filters the air.
MERV is important because there can be huge differences in the quality of air filters. It is not simply a case of one air filter being 10 or 15 percent more effective than another; some air filters can be 10 or 15 times more effective. And considering the importance of indoor air quality to our health and comfort, the simple mistake of choosing the wrong air filter is not an error you want to make.
That’s where MERV comes in. The MERV scale runs from 1 to 20, with higher numbers indicating higher filtering efficiency. The “efficiency” referred to by MERV is how well a filter removes small particles from the air. If it removes 5 percent of such particles, a filter would be considered to have low efficiency; 99 percent, and it would rate very high in efficiency. The reason it is a “Minimum” efficiency is because MERV rates filters in a worst-case scenario; a filter will work at least as well as its MERV number indicates, if not better.
Now, unless you are a scientist working in a clean room, you are probably not going to use the very highest MERV ratings. Even hospitals only use air filters with a MERV of about 16. The potential problem with the highest MERV ratings is that such filters are so dense that air can have a hard time passing through them. To use a very high-MERV filter, you will need to have an HVAC professional specially design your system to handle it. Otherwise, the federal EPA recommends air filters with a MERV of between 7 and 13. Since the HVAC system circulates the air through the filter multiple times each day, such filters are considered reasonably effective.
If you have any questions about which air filter would be best for your Fresno area home, contact us at Donald P. Dick Air Conditioning.
Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems). For more information about air filters and other HVAC topics, download our free Home Comfort Resource guide.
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