When determining whether a high-efficiency particulate air (HEPA) filter or an air filter with a lower minimum efficiency reporting value (MERV) rating is right for your A/C, heat pump or furnace, you must evaluate two things. The first is the difference between HEPA and MERV filters and the definition of each. The second is the level of performance you want out of your heating or cooling system’s air filter. Once you understand these basics, the choice should be clear.
MERV is a rating system that measures the effectiveness of air filters. It was created by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE). MERV ratings range from one to 20. The lower the number, the less effective the filter is at cleaning the air that passes through it. However, too high a rating will cause the cooling or heating equipment to work much harder to push air through the filter and could ultimately damage the equipment. A rating of at least five but no more than 12 should be sufficient for desirable air quality in any home that doesn’t have special air quality requirements (such as occupants with respiratory issues or severe allergies). Filters with MERV ratings above 13 are usually used in special settings, such as hospitals, and if adapted for residential use, will require serious modifications to HVAC equipment.
A HEPA filter has a MERV rating of between 17 and 20. It must meet regulations set by the U.S. Department of Energy and remove at least 99.97 percent of particles 0.3 microns or larger. While generally not found in centralized residential systems, as it would not allow sufficient airflow for the equipment to work properly, they can be used in residential forced-air systems that have been modified. HEPA filters are often used in portable air purifiers for people who suffer severely from allergies. Some are also used in vacuum cleaners to prevent allergen particles from being returned to the air.
When deciding between HEPA and MERV filters with lower ratings, remember that a rating between six and 12 is suitable for most residential use. If you suffer from allergies, consider a portable air purifier with a HEPA filter. For assistance in determining what filter is right for your system, contact Hansberger Refrigeration and Electric Company.
Our goal is to help educate our customers in Yuma, Arizona about energy and home comfort issues (specific to HVAC systems). For more information about HEPA and MERV filters and other HVAC topics, download our free Home Comfort Resource guide.
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