We have an air cleaner on our furnace, but our house still seems dusty and I have allergy problems. Would using a room air cleaner also help? Are they expensive to operate? Which design is best? -- W. D.
A -- Allergies have obvious symptoms, but there also are other serious long-term health hazards from breathing indoor air. Major health concern are microscopic particles that lodge deeply in the lung tissue and harmful organic chemicals.
A combination of some fresh air ventilation, a good central air cleaner in the furnace and several efficient room air cleaners provides the best protection. Room air cleaners, even larger ones on casters, typically use only a couple cents of electricity per day.
The most effective room air cleaners use a true HEPA (high efficiency particulate air) filter. This is the type that I use in my bedroom and family room. Be careful when making a purchase. Some packages use words like "HEPA-quality" or "HEPA-like," but they are not true HEPAs.
A true HEPA filter removes 99.97 percent of all particles down to .3 micron in size (includes tiny smoke particles and some bacteria). Because the HEPA filter media is very dense, its fan will use slightly more electricity.
Many HEPA and other media (filter-type) air cleaners include a carbon filter to remove odors and some organic chemicals. The greater the weight of the carbon material, the more effective it is. Some designs tout a carbon filter element, but there is too little carbon to really be effective.
Electrostatic types of room air cleaners work by charging particles so they stick to a collector plate. Small ion generators produce the same basic effect. The charged particles stick to objects in your room instead of being drawn into your lungs. Your vacuum cleaner then picks them up.
Certified CADRs (clean air delivery ratings) are the only standard way to compare air cleaner effectiveness. Air cleaning performance tests are done for smoke, pollen and dust particles. As a rule of thumb, do not select an air cleaner with a smoke CADR less than .65 times the room square footage.
Some small point-of-use models are helpful, too. A new mini-ashtray air cleaner removes the smoke before it mixes with the room air. Multispeed, mini-desktop ionizer air cleaners are quiet and ideal for the office too.
Write for Update Bulletin No. 916, a buyer's guide to the most effective room air cleaners, listing CADRs, filter types, speeds, features, prices and a sizing selector chart. Please enclose $2 and a business-size, addressed, stamped envelope and send your request to James Dulley, The Buffalo News, 6906 Royalgreen Drive, Cincinnati, Ohio 45244. Or instant download at www.dulley.com.
Q -- I am adding a masonry fireplace to my living room to help heat it. It will have a lot of heat mass, and I may also add a decorative water reservoir. Do you have any tips on leveling the long, raised hearth? -- T. A.
A -- Your idea is an efficient design concept. The more thermal mass you can get near the fireplace, the better. I do not know how you plan to build the reservoirs, but water is one of the best thermal storage media.
It is tricky to level a long hearth without special tools. Try using a long piece of 1/2 -inch-diameter clear tubing filled with water. Hang it in a U-shape across the hearth. The water height at each end will seek its own level.