Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, May 16, 1995 TAG: 9505160065
SECTION: EXTRA PAGE: 6 EDITION: METRO
SOURCE: David Butler
DATELINE: LENGTH: Medium
A: Most people rely solely on their heating and cooling system's filter to clean the air they breathe. However, this type of filter is ineffective at trapping all but the largest particles. After all, its job is to protect the air handler, not the occupants.
Nonetheless, the air in today's homes is often more polluted than the air outside. Year-round temperature control and air-tight construction techniques permit common household pollutants to accumulate unabated. The worst offenders include cooking byproducts, tobacco smoke, dust, fabric lint, animal dander, dust mites, aerosols and, of course, spores and pollen.
Notwithstanding the importance of proper ventilation, a high-efficiency filter system is the only way to rid your home of airborne particles. You'll not only breathe cleaner air, but your home fashions will stay clean longer and you'll do far less dusting. Needless to say, allergy sufferers stand to benefit the most.
As you discovered, sorting through the various filtration products can be a challenge. You can quickly narrow your choices by first resolving two issues: central vs. portable, and which filter technology.
If your home has forced-air heating and cooling, a central air cleaner is the way to go. It runs whenever the air handler runs. In most cases, the return duct plenum must be modified or extended to accommodate the filter assembly. If there's inadequate clearance around the air handler, you can opt for an in-wall model that fits behind the return grill.
Filter technology is a bit more involved. The easiest and least costly upgrade would be a pleated or electrostatic replacement filter. Both types are passive (no power hook-up) with prices ranging from $10 to about $80. Most electrostatic filters and several pleated filters are an inch thick, eliminating the need for modifications. However, they're only marginally better than a conventional filter.
High-efficiency particulate air (HEPA) cleaners are very effective at removing even the smallest particles. They have hundreds of square feet of special fiberglass fabric folded into a small space. Because of their high resistance, central units are usually installed "off-line" from the return plenum. Installed cost of a whole-house HEPA system can easily exceed $1,000 while operating costs (electricity and filters) average $100 to $200 annually.
Electronic air cleaners offer the best cost-performance compromise. Large particles are trapped by a pre-filter while particles as small as .01 microns (about 10,000 times smaller than a human hair) accumulate on electrically charged collector plates. Most have charcoal post-filters to remove odors.
Although the installed price of a whole-house electronic air cleaner can exceed $500, operating costs are practically nil. The main drawback: performance will suffer if the collector plates aren't cleaned regularly. The most convenient models have easy-to-remove collectors that are dishwasher safe.
If a central air cleaner isn't feasible, the best electronic room air cleaners are nearly as effective. However, to get whole-house coverage you must continually move it from room to room (or purchase additional units). A high-quality desktop air cleaner is a good choice for an office, kitchen or nursery.
To receive a list of companies that manufacture electronic air cleaners (desktop, floor-standing and central), please send $1.50 and a self-addressed envelope to David Butler F-510, Department TWN, 14713 Pleasant Hill Road, Charlotte, NC 28278-7927. The list includes toll-free phone numbers and a summary of each company's products.
TechTalk: Room air cleaners are rated according to how much air they can process, measured in cubic feet per minute (cfm). An 11- by 14-foot room with 8-foot ceilings has 1,234 cubic feet of air. An air cleaner should be able to process the air at least four times an hour (4,928 cubic feet). To calculate the minimum capacity for an air cleaner, divide by 60 to get cubic feet per minute (82 cfm).
by CNB