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Air filtering systems protect your heating and cooling equipment from dust and dirt
and provide you with fresh, clean air.
However, an air filtering system is only as good as the ducts that supply air to
them. The type of filter you use also dictates the effectiveness of your air filtering
system.
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The first step in filtering air is to control the quality of the air being distributed.
Leaky duct systems allow dust and other pollutants to be drawn in and distributed
throughout a home. Sealing the duct system with mastic is the first and most important
step towards improving the quality of the indoor air. For information about system
sealing, contact EWEB's Energy Management Services Department and ask about our
duct testing and sealing program.
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When choosing an air filter, determine what you want to filter from the air (dust,
pollen, etc.), how much you want to spend and how often you will be able to do maintenance.
Generally, the less expensive the filter, the less effective the filter may be at
removing pollutants. The more expensive, higher efficiency filters are more effective,
but require more maintenance.
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The least expensive and most common filter is a disposable paper and spun fiberglass
panel or a washable "hog's hair" mat. These filters remove less than 5
percent of the particulates that pass through them and offer little protection for
human lungs. They should be replaced every one to two months to prevent air restriction
to your forced-air unit. The average cost of these filters is under a dollar.
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Electrostatic panel filters use static electricity to filter the air. Static electricity
is created as the air flows through the filter. Some of these filters contain plastic
materials which are charged with positive and negative charges to attract larger
particles. These filters remove 10 to 15 percent of the particulates that pass through
them, including some larger mold spores and pollen. The filters range in cost from
$16-$20. Filters should be cleaned or replaced on a regular basis (refer to manufacturers'
recommendations) to maximize your forced-air unit's efficiency.
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Extended-surface filters are pleated to increase the surface area, allowing for
the removal of 20 percent more particulates. An extended-surface filter will cost
more than a standard panel filter and will last from three months to a year. The
filters cost about $15.
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An electronic air cleaner uses high voltage to charge particles in the airstream.
The charged particles collect on an oppositely charged metal plate. If properly
maintained, electronic air cleaners can remove up to 90 percent of the particulates
that pass through the unit. Because regular cleaning is so important, the equipment
should be installed in an easily accessible area. Contact any heating and cooling
contractor for a price estimate.
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High-efficiency filters provide the best filtering available. HEPA filters remove
97 to 98 percent of the particulates that pass through them. These high efficiency
filters also restrict air flow through your system. HEPA systems must be designed
and installed by a professional and can cost several thousand dollars.
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