Pleated Air FiltersPleated air filters are often used in central heating/cooling systems by allergy and asthma sufferers to help provide relief from certain contaminants.
How effective are they?Pleated air filters are tested for their efficiency in removing particles from the air. A rating method that is used to show how different filters compare to one another is called a MERV rating. MERV ratings use a number to rate the filter (MERV 1 to MERV 19). The higher the number, the better the filter. Typical fiberglass filters that are found on most heating/cooling systems remove large dust particles. This type of filter is used only to protect the heating/cooling equipment and allow the smaller particles to flow back into the living area. The MERV rating of this type of filter is typically in the MERV 1 to MERV 4 range. A MERV 8 filter will typically be 50% efficient in removing particle sizes such as lead dust and large bacteria. A MERV 12 filter has the ability to trap pollen, mold and dust mites. Particle that are found to be most harmful are those that cannot be seen with the naked eye (viruses, smoke, dust mite feces). An electronic air filter would be the filter of choice to combat these small contaminants. A HEPA filter is also very effective for these smaller particles, but care should be used in choosing the right one. If you are thinking about buying a HEPA or any type of pleated air filter, you should have the pressure in your duct system tested by a qualified heating/cooling contractor. This is a quick test (aproximately 15 minutes) and is similar to a blood pressure test. Doing this will tell if your system can handle the additional resistance to airflow that pleated filters create. Using pleated filters in systems that are already operating at pressures that are too high will not only cause your heating/cooling system to underperform but will also decrease the life of your system.
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