Sunday, June 20, 2010

Furnace Filters - Merv Ratings

1. Define MERV rating?Minimum Efficiency Reporting Value
2. MERV ratings are a method of determining the efficiency of an air filter used with heating and air conditioning equipment. The efficiency is determined by adding particles of varying sizes (1-12) into a controlled testing environment. The particles are added upstream of the test filter and a laser particle counter samples the air before it enters the filter and after it leaves the filter. The two particle counts are compared to calculate the Particle Size Efficiency of the tested filter. Once this is determined, a MERV Parameters chart is used to determine the MERV rating.
3. 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.
4. 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.
5. 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. Filter replacement it is recommended a minimum of one time per season depending on usage. If your air filter becomes clogged up with dirt and other indoor pollutants they will decrease the efficiency of your heating and air conditioning system leading to wasted energy and may cause damage or premature breakdown to your heating and air conditioning equipment.
6. 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.
7. 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.
8. Some of the benefits of using a high-efficiency air filter are energy savings, allergy and asthma relief (in many cases), longer equipment life, cleaner home, less need for repainting and furniture cleaning.