Furnace Filters
The filter protects the furnace from particles in the air, and helps reduce household dust. A clean filter also ensures your furnace operates at peak efficiencies.
Depending upon the type of filter used, the filter should be cleaned or replaced every one-to-three months during the heating season. If you run your furnace fan continuously year-round, you should maintain your filter year-round.
Before changing or cleaning your filter, make sure the power is turned off to the furnace. Vacuum the filter holder, accessible duct areas, and fan compartment. While in the fan compartment, check the fan belt (if applicable) for fraying or wear and ensure proper tension (it should give about one inch to a gentle push of a finger).
If you are replacing your furnace with a new, high-efficiency model, consider your options in furnace filters. Furnace filters fall into three basic categories: mechanical, electronic, and bypass. Following is an overview of the features and benefits:
Mechanical filters
Mechanical filters are separated into two types: flat filters and pleated filters. Flat filters are typically low-efficiency filters, removing 10 per cent or less particulate.
Pleated filters are a slightly more efficient alternative to flat filters. Pleated filters are made of cloth or synthetic fibres folded accordion-style. These filters typically fit within a standard filter application.
Electronic filters
These filters are electrically charged and typically particles pass through numerous stages making them more efficient than mechanical filters. Each stage of filtration is designed to eliminate progressively smaller particles (referred to as microns); therefore the more stages a unit has, the more efficient it is. Filters of this type do produce ozone, which may cause health issues for occupants. However, even with these types of filters, ozone levels are typically higher outside the home environment. For more information, visit the CMHC link provided at the end of this document.
There are two types of electronic filters: charged media filters and Electrostatic Precipitator (ESP) filters. Charged media filters are lower-efficiency electronic filters, and cost roughly $150.
The higher efficient multiple stage ESP filters, depending on the efficiency of the model, range around $500 to well over $1000. Higher efficient electronic filters will normally require some modification to the duct system.
Bypass/HEPA filters
HEPA filters have high overall performance; however, these systems require special installations and/or duct modifications, and are substantially higher in cost than any other models mentioned in this document. This system is not normally used in homes, unless there is a concern by those with severe allergies or asthma.
A comprehensive evaluation of residential furnace filters was conducted by Canada Mortgage and Housing Corporation (CMHC). To view the study and their findings for further information, please click here.