When was the last time you changed the air filter in your heating and cooling system? You may have noticed that, over time, it becomes coated with “stuff.” Your air filters may reveal a dirty little secret - the air you breathe may not be as fresh as you think!
Dirt, Dust and Indoor Particulates
Air filters are an essential part of the heating and cooling system intake ducting. Its designed to capture “particulates” before they get to your heating and cooling system. According to the EPA1, a basic air filter with a low Minimum Efficiency Reporting Value (commonly known as MERV) may capture some of your home’s airborne particulates including, but not limited to:
- Dust
- Pollen
- Animal dander
- Larger particles that contain dust mite and cockroach allergens
Air filters are intended to minimize the debris landing on fan motors and heating or cooling coils. Routinely replacing the air filter as directed by the manufacturer’s guidelines can protect your HVAC equipment and may help your HVAC system from losing efficiency over time. A clogged air filter can increase your air conditioner's energy consumption by up to 15%.2
What is a MERV Rating?
MERV is short for ‘Minimum Efficiency Reporting Value’, and is number value that distinguishes the filtration ability of air filters installed in your HVAC system.3 The MERV numbering system may range from 1 to 20. The higher the MERV number, the fewer particles and airborne contaminants that the filter should allow to pass to your HVAC equipment.
Residential furnaces and air conditioners commonly use 1 to 4 MERV rated filters. The EPA says that basic mechanical air filters may not remove all particulates from the air.4 However, these filters may stop some of the larger particles from passing through to the HVAC equipment.
If the MERV rating if higher, there is a better chance of trapping “bacteria, some spores, a significant fraction of cat and dog allergens, and a small portion of dust mite allergens.”5 The EPA suggests that filters with a higher MERV rating between 7 and 13 can be as nearly as effective as true HEPA filters.
However, some residential HVAC systems may not have enough fan or motor capacity to accommodate higher efficiency filters. Therefore, talk with your technician about your HVAC manufacturer’s recommended filter type before upgrading to higher MERV filters. Installing true HEPA (High-Efficiency Particulate Arrestance) filters in an existing residential HVAC system typically requires professional modification of the system.
If you are concerned about indoor pollutants and air quality, discuss possible solutions and products with your licensed or professional HVAC dealer.
1, 2 Guide to Indoor Air Cleaners in the Home. (2014, July). Retrieved from EPA: https://www.epa.gov/sites/production/files/2014-07/documents/aircleaners.pdf
3 What Are MERV Ratings and How Do They Work? (n.d.). Retrieved from Air Purifier Guide: http://www.airpurifierguide.org/faq/merv-ratings
4 Indoor Air Quality (IAQ). (n.d.). Retrieved from EPA: https://www.epa.gov/indoor-air-quality-iaq/residential-air-cleaners-second-edition-summary-available-information#summary
5 Maintaining your Air Conditioner. (n.d.). Retrieved from Energy.gov: http://energy.gov/energysaver/maintaining-your-air-conditioner