Are Air Filters Better, The Higher The MERV? Not Necessarily

Air filters for your HVAC system protect your equipment and help clean your indoor air. The MERV (minimum efficiency reporting value) rates filters based on how effective they are at removing the smallest airborne particles. For residential filters, the scale runs from 1 to 16, with higher ratings given to filters that remove smaller particles. However, a high MERV rating doesn’t necessarily mean the filter will work well with your particular system. You’ll want to consider other factors as well.

Following is a basic breakdown of what you can expect from different MERV ratings:

  • MERV 1-4. The inexpensive fiberglass filters trap bigger particles such as some household dust, pet hair and fibers from carpets, drapes and clothing. They trap less than 20 percent of the particulates in your air. However, they do serve the basic function of keeping your heating and cooling equipment clean while maintaining airflow.
  • MERV 5-8. Pleated filters usually carry these ratings and are able to trap mold spores, dust mite waste, pet dander, hair spray and other particulates. The pleats provide more surface area for capturing airborne particles, while also providing more opportunity for air to flow through unimpeded. In most cases, a MERV rating of 8 is sufficient for residential HVAC equipment.
  • MERV 9-12. Higher quality or thicker pleated filters can trap particles as small as Legionella, milled flour and humidifier dust, and up to 75 percent of the dust in the air.
  • MERV 13-16. These high-efficiency filters are more likely to impede airflow, though they are the ones to use if your home has special air-quality concerns.

When air filters are capable of trapping smaller particles, their more complex filtering system does tend to slow airflow through your HVAC system. Less airflow reduces the operating efficiency of your HVAC system, and if you use a gas furnace, reduced airflow can contribute to problems with the heat exchanger that may shorten its operating life. Your goal should be to choose an air filter for your particular system that provides an optimum balance between providing good air quality and maintaining system airflow.

Before switching to a higher-rated filter, you should check the owner’s manual for your HVAC equipment or consult with an HVAC professional to avoid damaging your system. When you do switch to a denser filter, you’ll want to check it more often, since it traps more particulates.

To learn more about air filters, please contact us at Cool Power, LLC. We’ve provided HVAC services for Long Island since 1975.

Our goal is to help educate our customers in Hauppauge, New York and the Long Island area 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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