Keep Cool. As I write, the outside temperature here in Louisville Kentucky is a humid, blistering 93 degrees and climbing. Last year we installed a new 15 SEER HVAC system and I was reminded that if I wanted to keep my A/C unit running efficiently, while cutting down on our energy bill, I’d need to install the correct air filter and replace it regularly. The shelves of the home improvement stores were stacked floor to ceiling with a dizzying array of filters. Which to choose? Fortunately ANSI has adopted a standard that helped us make an informed decision.
How To Measure Efficiency. Filtration efficiency is measured in MERVs. MERV is an acronym for “Minimum Efficiency Reporting Value” and was developed by the National Air Filtration Association, whose membership is composed of 600 air filter distributors, manufacturers and engineers. The higher the MERV rating (1 through 20), the more efficiently the filter filters the air.
MERV measures three pollutant removal capabilities:
1 Particle Size: The particle size of the contaminant you are trying to remove. Particles are measured in micrometers. The greater the size of the particle which escapes filtration and arrives in your living room, the less efficient the filter.
2 Average Arrestance: A measure of the ability of an air filtration device to remove synthetic dust from the air. The greater the arrestance, the more efficiently it removes the synthetic dust from the air.
3 Dust Spot Efficiency: This measures the ability of a filter to remove atmospheric dust from the air. In effect it is measuring the filter’s ability to remove large particles,those that tend to soil building interiors.
What Pollutants are Removed? From the table below you’ll see that the MERV ratings are grouped into 5 tiers. The higher the tier number, and the higher the MERV rating within that tier, the more efficiently the pollutant is removed.
- Merv 1 – 4 rated filters remove pollen, dust mites, cockroach debris, sanding dust, spray paint dust, textile fibers and carpet fibers.
- MERV 5-8 rated filters remove mold, spores, dust mite debris, cat and dog dander, hair spray, fabric protector, dusting aids and pudding mix.
- Merv 9-12 rated filters remove Legionella (bacteria which cause Legionnaires’ disease), humidifier dust, lead dust, milled flour, auto emission particulates and nebulizer droplets.
- MERV 13-16 rated filters remove bacteria, droplet nuclei (sneeze), cooking oil, most smoke and insecticide dust, most face powder and most paint pigments.
- MERV17-20 rated filters remove virus, carbon dust, sea salt and smoke.
My Choice. We’re a normal family suffering the occasional mildly irritating allergies so common in the Ohio Valley. After consulting a few air conditioning technicians, and considering the pollutants we’re exposed to, I have chosen to use an 8 MERV rated filter,which works just fine for our needs. I follow the manufacturer’s recommendation and change our filter every 3 months. When the time comes to sell our Louisville home we will have preserved the air conditioning unit, suffered fewer break downs, lengthened its life, and will have increased the odds of not having to buy a new unit. All for less than 5 bucks every 3 months!
Where to Buy. I went bargain hunting on Google and ultimately landed up ordering directly, by phone, from a Louisville Kentucky air filter manufacturing giant, Koch Filter Corporation, located near the University of Louisville. They had the best price and I felt good about buying locally. Their contact information is 625 West Hill Street, Louisville, KY 40201 / 1-800.757.5624 and 502.634.4796 / firstname.lastname@example.org.