Air Cleaner Removes Allergy-Causing Pollen

QUESTION: I want to improve the cleanliness and air quality in my home due to my children’s allergies and general health concerns. What types of central whole-house air cleaners are best and most efficient?

ANSWER: In addition to removing allergy-causing pollen, molds, smoke, dander, dust, etc., from the air in your home, a central whole-house air cleaner can reduce the operating costs of your furnace and air conditioner. By keeping heat exchangers and coils cleaner, heat transfer is more efficient.

There are several basic types of central air cleaner designs available. One of the most effective (efficiency of above 99%) is a bypass-type of high-efficiency particulate air (HEPA) filter. You attach it to the ductwork near your central furnace or air conditioner.

HEPA filters trap even the smallest particles and are the types used in hospital operating rooms. The replaceable filter element should last about one year. A separate charcoal filter removes odors and some organics.

Since a HEPA filter is so dense and cleans so completely, a central bypass system uses its own small electric blower to circulate the room air through it. A sail switch in the air-return duct turns on the filter blower whenever the central furnace or air-conditioner blower comes on.

Another design of air cleaner is a self-charging electrostatic filter. The air passing through the filter material creates a natural static charge. This causes the dust and dirt particles in the air to stick to the filter. It just slips into your existing filter slot so no modifications are needed.

One electrostatic air cleaner has a whistle-type sensor built into it. As the filter removes dirt from the air, it slowly gets clogged. When it gets clogged to the point that it reduces the efficiency of your furnace or air conditioner, a whistle sounds to alert you that it should be cleaned. Putting it under the shower or squirting it with a hose releases the dirt.

Electronic air cleaners are also very effective. Electricity is used to charge the dirt particles as they pass through the air cleaner. These use about as much electricity as a 40-watt light bulb. They should be cleaned often per manufacturers’ recommendations to maintain their effectiveness.

Another type of air cleaner is a pleated-media filter. It is somewhat like an HEPA unit, but since it does not have its own blower, it can’t be as dense or as effective. Both the electronic and pleated-media air cleaners require modification to your furnace ductwork.

You can write to me at the address below for Utility Bills Update No. 134 listing addresses and telephone numbers of manufacturers of various types of high-efficiency central air cleaners, product information and specifications. Please include $1.50 and a self-addressed business-size envelope.

Central Air Cleaner

One of the most effective central air cleaners uses a combination of filters to screen out the smallest particles. One type, the high-efficiency particulate air filter, is so dense the unit needs its own small electric blower to circulate room air through it.