Filtration: Removing Pollutants from the Air
Used with your heating and cooling system, filters make a big difference in the quality of air circulating throughout your home and work place. Inadequate filtration can allow for a build-up on fans coils and other surfaces. Factors that affect filter efficiency include fiber size, fiber density, airflow rate, and particle diameter.
When selecting an air filter look for the MERV rating. MERV ratings are used to rate the ability of an air filter to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall efficiency of a filter. Higher MERV ratings mean fewer dust particles and other airborne contaminants pass through the filter.
Types of filters:
- Panel filters: These are usually 1″ thick fiberglass filters, are the typical furnace filters installed in the ductwork of most home heating and/or air conditioning systems. These filters do little to remove contaminants from the air. The primary function of these filters is to prevent large debris from damaging the furnace fan blower.
- Pleated filters: basically panel filters that have been pleated or folded to provide more surface area. These filters are typically more efficient than a panel filter by increasing the surface area for collecting particles. It is important to change the filter on a regular basis so as not to restrict airflow.
- High Efficiency Particulate Air (HEPA) filters: are extended filters that remove sub-micron particles with high efficiency. HEPA filters consist of a core filter that is folded back and forth over corrugated separators that add strength to the core and form the air passages between the pleats. The filter is composed of very fine sub-micron glass fibers in a matrix of larger fibers. These types of filters are not designed to fit most standard furnaces. They generally need a separate system consisting of a fan and filter.
- Electronic air cleaners use an electrical field to trap charged particles. Like mechanical filters, they can be installed in central heating and/or cooling system ducts. Electronic air cleaners trap a high percentage of particles from the air passing through them.
Replace your filter at the stated intervals instructed by the manufacturer, usually about every three months, i.e., the first day of every season. Replace more often if you are introducing higher levels of particulates into your home, such as when renovations are being done. Also, consider more frequent replacements if you have a family member with asthma, allergies or another lung disease.
It is important to understand that air filters only protect the air ducts from air entering the ventilation system. Debris must be professionally removed by an air duct cleaning contractor prior to implementing a filter maintenance program to improve indoor air quality.