What is MERV?
In this case MERV is a good way to help judge the effectiveness of an air conditioning filter. As you might have expected MERV is an acronym for Minimum Efficiency Reporting Value which was developed by the American Society of Heating, Refrigeration and Air Conditioner Engineers, ASHRAE. The MERV value represents a performance indicator for an air conditioning filter from the beginning to the end of the filters life. The highest MERV value is 16 and the lowest is 1, in this case the higher the value the more efficient the filter will be in trapping airborne particles.
One factor to consider is air flow through the system. Air conditioning systems are designed to operate most efficiently with the airflow remaining within the designed range. More air flow is not good but is difficult to achieve but low air flow is not good either and is quite easy to achieve. Leaving a dirty air filter in place may result in low air flow and possibly cause the system to malfunction. In some cases, using an air conditioning filter that is too restrictive for your system may cause low air flow problems as well.
In the old days the filters were commonly the fiberglass variety which might equal a MERV 1 or 2. These provide very good flow but not much filtration beyond the sizable particles in the air. They will help to prevent the evaporator from getting too dirty too fast but they don’t do much to improve air quality. On the other end of the spectrum are the MERV 15 or 16 filters which do an excellent job cleaning the air but are too restrictive for most home systems.
If you are wondering what MERV to try keep these recommendations in mind;
-ASHRAE recommends MERV 6 or higher
-US Department of Energy recommends MERV 13
-Leadership in Energy and Environmental Design, LEED recommends MERV 8 at a minimum
Keep the air flow issue in mind and if possible start with a MERV 6 and work up if no system performance problems are noted. Most importantly, change you air conditioning filters regularly according to the manufacturer’s recommendation.
Filed Under Technical Information |
Tagged With Air Conditioning Filter, Airflow, ASHRAE American Society of Heating Refrigeration and Ai, Efficiency, LEED Leadership in Energy and Environmental Design, MERV, Recomendations, System Performance, US Dept of Energy
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This is a great resource for some technical information about MERV ratings, and what they really mean to you in regard to what is filtering what size microns and so forth.
Thanks for the info!