I've had one of these on my furnace for decades. it works great at taking odors and smoke, pollen anything out of the air. Clean it once a year.
3. Electronic filters
Electronic Filters: These work paticularly well on smoke particles and never need replacing, though they must be scrubbed every few months. Photo by Darrin Haddad
These high-tech units, sometimes called electrostatic precipitators, are also incorporated into the ductwork. As air passes through, a high-voltage current puts an electrical charge on particles. At the other end of the unit, oppositely charged collector plates grab the particles like a magnet.
Electronic filters work especially well on smoke particles too small to be trapped in media filters. One independent test found such filters worked about 30 times as well as regular fiberglass filters. (There is no industry yardstick for measuring the effectiveness of whole house units because performance is affected by a home’s blower and ductwork.)
Unlike media filters, electronic filters never need replacing, but the aluminum collector plates must be cleaned in soapy water every few months. The process of charging particles, called ionization, may produce trace amounts of ozone, a lung irritant. Electronic filters cost $600 to $1,000 installed and require a 120-volt electrical outlet.
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