Today's
TECHNOLOGY AND YOU

Q: Our bathroom vent fan sounds like a Boeing 747 at takeoff. I should replace it with a new efficient, quiet vent fan. How can I tell which fans are the most quiet and efficient and what size fan is best? -N. F.

A: There have been many recent design improvements in bathroom vent fans for more quiet and energy efficient operation. Many of the new super-quiet ceiling-mounted and remote in-line models are difficult to hear at all. The new styles are designed with low profile grills (some with natural wood) to blend almost imperceptibly into any bathroom decor.

It is very important to adequately ventilate bathrooms. Excessive moisture quickly diffuses throughout your house causing premature deterioration, mold growth and allergy problems.

The most efficient new vent fans use only 15 to 20 watts of electricity. Running one is much more efficient year-round than just opening a window and hoping the wind is blowing the proper direction. Built-in anti-backdrafting louvers block the leakage of outdoor air when the fan is not running.

New convenience features also make replacing an old vent fan a wise move. Several models have built-in humidity sensors to automatically control when the fan starts and stops. If you can get your children to use the fan at all, they often forget to turn it off. This automatic feature is a real energy saver. By eliminating overuse, less electricity is consumed and less conditioned air is drawn out of your house.

Several models, like the Nutone SmartSense, take this one step further. These also include motion sensors to automatically start the fan and switch on the light when someone enters the bathroom. The light can be set to go off within 5 to 60 minutes after no motion is detected. This also is ideal for children. All of these automatic controls can be switched off for manual override or used individually.

Many new vent fans have optional fluorescent light fixtures and built-in night lights. Eighteen-watt fluorescent lights save electricity. New fluorescent tubes produce flattering color rendition and will not make you look like a walking corpse like old tubes did. The 7-watt built-in night light is generally adequate light for bathroom use at night.

Since most vent fans look alike, compare the sound-level specifications. Sound level is rated in "sones." The quietest new models rate from 0.5 to 2.0 sones with larger fans usually being the loudest. As a reference, 1.0 sone is about as loud as a new quiet refrigerator. The fan packaging should list the sones rating. Don't buy one without a rating listed.

Internal design features make the difference between a noisy and a quiet fan. Special sound absorbing scrolls and flexible motor mounts reduce noise, just the shape of the interior air chamber has a major effect.

It is very important to size the vent fan properly for effective quiet operation. Don't just buy a big expensive one. As a rule of thumb, the air flow capacity (in cubic feet per minute-cfm) of a bathroom vent fan should be about 10 percent greater than the square footage of

James Dulley is a mechanical engineer who writes on a wide variety of energy and utility topics. His column appears in a large number of daily newspapers.

Copyright 1996 James Dulley

18 ILLINOIS COUNTRY LIVING NOVEMBER 1997

the bathroom. For example, a 50 square foot bathroom should have a 55 cfm vent fan.

Installing a remote in-line vent fan is a quiet and effective option. The fan, sometimes called a tube fan, is mounted up in the attic. It is attached with flexible dryer duct to a grill in the bathroom ceiling.

Since the fan motor is located away from the bathroom, it is very quiet. By using a "T" duct fitting, one in-line fan can vent two areas simultaneously — two bathrooms or above the sink and in the shower stall. A low-voltage fan/ light unit is the only other safe option for the shower itself.

Write for Utility Bills Update No. 761 -buyer's guide of 13 super-quiet bathroom vent fans listing air flow capacities, sound levels, features, diagrams, prices and a sizing chart. Please include $2 (with checks payable to Jim Dulley) and a business-size SASE. Mail to: Jim Dulley, Illinois Country Living, P.O. Box 3787, Springfield, IL 62708. To read previous columns, go to http://www.dulley.com.

NOVEMBER 1997 ILLINOIS COUNTRY LIVING 19