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Wednesday, January 12, 2011

Furnace Filter MERV Ratings

The quality of air filter for your furnace is a very important aspect of your heating system, and hopefully you want the best grade filter as it directly impacts the air you are breathing in your home.  Air filters are rated according to MERV, which stands for Minimum Efficiency Reporting Value.  Here are some quick facts about MERV:
  1. MERV ratings range from 1 - 16 and measurements are in microns. Some of the common particles related to MERV ratings are household dust, pet dander, viruses, tobacco smoke, mold spores, bacteria and pollen.
  2. The most common filters found in homes today have a MERV rating of 1 to 4. Typically these are disposable fiberglass filters purchased from a big box store and do not do a good job of air filtration because they don’t stop particles smaller than 10 microns. Improper air filtration can lead to air conditioner and/or furnace problems as well as poor indoor air quality.
  3. Merv 5 to 8 rated filters are a better choice. These filters will not only keep your equipment running clean and efficient when properly maintained, they also do a better job of filtering smaller dust particles (as small as 3 microns) that trigger symptoms with allergy sufferers.
  4. Filters with a MERV rating of 9 to 12 are considered high-efficiency filters and capture particulate in the 1 to 3 micron range. These filters are a great choice for home owners who want the best air filtration at an affordable price. Much like the higher rated MERV 5-8 filters, these filters should also be replaced at regular intervals to avoid wasted energy, premature repairs or breakdown to your heating and air conditioning equipment.
  5. The most efficient filters have MERV ratings of 13 to 16 (HEPA air filter) and will stop particles as small as .3 microns. These filters are hospital grade and have been adapted for use in residential applications. Super high efficiency air filters should be installed by a professional heating and air conditioning contractor. Improper installations could lead to severe damage to your furnace or air conditioner.
  6. Merv Griffin hosted his own talk show and created the game shows Jeopardy and Wheel of Fortune.
Always remember, no matter which kind of filter you choose to have in your system, they all need to be changed regularly.  The best possible filter will do you no good if it never gets changed and gets all clogged up with dust and other such particles, SO KEEP THOSE FILTERS CHANGED!!



  1. Generally speaking, the higher the MERV rating, the better performing the furnace filter will be. Replacing your furnace filter regularly can help extend the life of your furnace and improve its efficiency rating.

  2. This article will provide a good resource on why filter maintenance is very important.Thank you for sharing.

    Furnace Air Filters