What’s the job of an HVAC air filter and how do you know your air filter is right for the job? While your furnace or air conditioner is running, all the air inside your home passes through the HVAC filter.
Why Filtration Matters
Indoor air contains airborne particulates, seen and unseen. Dust is a catch-all term referring to an airborne miscellany of fibers from clothing and carpets, outdoor soil particles, human hair and pet fur, dust mites, pollen, and other tiny particulates. Dust is a common trigger for allergies, as well as for exacerbating chronic conditions like asthma. It’s also a housekeeping nuisance as it settles on furniture and other surfaces.
How HVAC Filtration Works
Mounted inside your HVAC air handler, the filter extracts dust from air flowing back through return ducts that extend to rooms throughout the house. Depending on the season, filtered system airflow is then heated by the furnace or cooled by the central AC coil. Filtered air then flows back to all rooms through supply ductwork.
Rating Air Filter Efficiency
Filter efficiency refers to its ability to capture airborne particulates down to a specific size. The most common filter-rating metric is MERV (Minimum Efficiency Rating Value). The MERV rating is typically found in the information on the filter’s label.
- MERV is a numeral ranging from 1 to 16 for residential uses. The higher the MERV rating, the more efficiently the filter captures the tiniest particles.
- A MERV 2 rating is typically the most inefficient and inexpensive fiberglass filter, capturing only the largest airborne particles.
- More efficient filters in the range of MERV 8 to 13 utilize pleated cotton or polyester media and generally represent the best compromise between optimum airflow and efficient filtration, removing more than 50% of particulates down to a size of 0.3 microns.
- Filters above MERV 16 restrict airflow excessively and therefore should not be utilized without special alterations to home ductwork.
- Change the filter regularly (generally monthly) during air conditioning season and every other month when the furnace is running.
For more about optimum air filter efficiency for your home, contact Ace Hardware Home Services.
