The air filter for your HVAC system protects your heating and cooling equipment and helps improve the quality of the air in your house. Though filters appear fairly straightforward, there’s actually a science behind how they work. The industry uses the MERV (minimum efficiency reporting value) system to rate how effectively an air filter traps the smallest particles.
For residential purposes, the MERV scale runs from 1 to 16, and higher values indicate better filtration. Cheap fiberglass filters trap larger particles only, and have MERV ratings from 1 to 4. Pleated filters are commonly available as well, with MERV ratings in the middle of the scale. These mid-range filters are often recommended for ordinary household use, provi
ding a nice balance between maintaining air quality and system airflow.
HEPA (high efficiency particulate air) filters have been used for decades to filter air in manufacturing and health facilities. These filters trap nearly all particulate matter, but usually have too much air resistance to use directly inside a blower. Whole-house air filtration systems with HEPA filters often require an additional or more powerful fan to boost the airflow so that it matches what the manufacturer recommends for your system.
The federal EPA reports that filters with MERV ratings from 7 to 13 may be nearly as effective as a HEPA filter in cleaning your home’s air, but if you go over the threshold that the manufacturer recommends for your blower, it may place your equipment at risk. The best strategy is to consult with your trusted HVAC contractor. They will measure the airflow your system puts out to make sure that it’s adequate for your system, even with the denser filter.
It’s also important to make sure that the air filter fits your system physically. Any gaps around the frame that holds the filter will pull unfiltered air through your blower and ducts. With any grade or type of filter, it’s important to check them regularly, since a clogged filter can reduce system efficiency, degrade indoor air quality and eventually damage your equipment.
If you’d like to learn more about air filters and your HVAC equipment, please contact us at Marsh Heating & Air Conditioning. We’ve provided top-notch HVAC services for the Twin Cities area since 1974.
Our goal is to help educate our customers in Minneapolis-St. Paul, Minnesota 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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