In this issue of "Doug Talks..."
Why changing Air Filters
is Important
As air moves through your house, air filters trap and collect large and small particles such as dust, allergens and microorganisms. According to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), this filtration helps provide healthier indoor air quality. A filter's MERV number indicates how it's rated to remove these particles.
What is a MERV rating? An air filter’s minimum efficiency reporting value (MERV) rating measures how effectively the filter stops dust and other contaminants from passing through the filter and into the air stream. Filters with higher MERV ratings trap small particles more effectively than filters with lower MERV ratings.
In general, filters with a rating of MERV 16 or below are considered to be HVAC-system-grade filters for residential, commercial and general hospital use. MERV 17 through MERV 20 filters are typically used in surgical operating rooms and clean rooms that require absolute cleanliness.
MERV Filter Ratings and Efficiency
When selecting the right filter, higher is not always better. Using an air filter with a MERV rating higher than what your furnace or air conditioner manufacturer recommends can actually impair its performance. The smaller pores in more highly-rated air filters create resistance to air flow, and if the filter is used in an HVAC system that is not designed to handle this resistance, it can lower the system's efficiency, decrease indoor air quality, and put strain on the system's fan.
How often should I Change my Home Air Filter?
Many factors influence how often you should replace your air filters with a new filter: indoor air quality, number of pets, household size, construction around the residence, etc. Below are some averages for a residence:
- Ordinary suburban home without pets: every 90 days
- Vacation house or one occupant and no pets or allergies: every 6–12 months
- One dog or cat: every 60 days
- More than one pet or if anyone has allergies: 20–45 days
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