Homeowners who faithfully change their air filters regularly, but don’t use the right filters when replacing them, may discover less than desirable results. Use a filter with a MERV rating that’s too low, and even with regular filter changes, indoor air quality won’t improve. Use a filter that’s rated too high in efficiency than your HVAC system allows, and it can result in poor system performance and eventual breakdowns. Learn the basics of the minimum efficiency reporting value (MERV) system to choose the best filter for your air conditioner, heat pump or furnace.
If you understand the purpose of the MERV system, you’ll better understand why homeowners should be careful when choosing an HVAC filter. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) created the MERV (minimum efficiency reporting value) system in order to employ a uniform testing standard for air filter efficiency. It basically rates air filters based on how much (and what size) particulate matter they can remove from your indoor air. What MERV doesn’t show, however, is a filter’s effect on system airflow. This is one factor that you can’t afford to ignore.
- MERV 1 to 4 filters trap very large particles, and do not restrict airflow through the filter, giving the HVAC system enough air to operate. They serve the basic purpose of protecting system components from dust and dirt, but won’t improve air quality.
- MERV 5 to 12 filters trap small to large particles, and shouldn’t restrict airflow – if you regularly change the filter. However, consult your HVAC equipment’s manual or talk with your HVAC contractor to find the best filter in this range for improving air quality while maintaining system airflow. (These filters are often pleated, which gives them more surface area both for capturing pollutants and allowing free airflow.)
- MERV 14 to 16 (and high efficiency particulate air (HEPA) filters rated 17 to 20 MERV, may impede the necessary airflow that your HVAC system depends on, and may require equipment modifications to work in your system. Consult with a pro before choosing one of these high-efficiency filters.
Rest assured, there’s a MERV air filter uniquely suited to work with your HVAC system to protect it from dirt buildup and encourage higher quality indoor air, while delivering sufficient air for the equipment to operate well. For expert advice on choosing a filter for your air conditioner or furnace, please contact us at Ace Hardware Home Services. We’ve served homeowners in greater Dayton since 1978.
Our goal is to help educate our customers in Dayton, Ohio about energy and home comfort issues (specific to HVAC systems). For more information about changing your air filters and other HVAC topics, download our free Home Comfort Resource guide.
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