Furnace Filters – What are Merv Ratings

What does MERV rating stand for? Minimum Efficiency Reporting Value. 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.

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.

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 an air conditioner or furnace problems as well as poor indoor air quality.

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.

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 homeowners 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.

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.

The most common benefits of using a high-efficiency air filter are:

  • Energy savings because of cleaner furnaces and cooling coils.
  • Allergy and asthma relief (in many cases) because of reduced airborne particulates and allergens.
  • Longer heating and air conditioning equipment life.
  • Cleaner homes leading to less need for repainting and furniture cleaning.

ASI Hastings offers a complete line of high-efficiency air filters, UV air purification, humidifiers and other indoor air quality products. Call 1 (619) 350-3205 or visit us at asiheatingandair.com for a free in-home consultation. For your convenience, ASI Hastings offers evening and weekend service at no extra charge.

By | 2018-08-13T14:04:19+00:00 August 12th, 2010|Articles|