New bathroom vents are quiet, attractive and efficient
Q: I know it is important to run our bathroom vent fan, but I seldom switch it on because it is so noisy. We are remodeling our bathroom now. What are the best new quiet vent fans and what size is best? - Kathy J.
A: • Running a bathroom vent fan is very important for good indoor air quality (moisture, odors, allergies). Even if your bathroom has a window that you can open, running a vent fan for the proper amount of time provides more effective ventilation year-round. Often when you crack open a window, you forget to close it until you use the bathroom again. Although your old bathroom vent fan may sound like it is using a lot of electricity, fan motors are actually fairly low wattage. By removing the excess moisture, especially in the summer when air-conditioning, your electric bills can be reduced overall.
In the winter, the moisture, although it does not increase your heating bills, often causes window condensation that can damage the drywall around the windows. In some instances, the moisture will migrate into the wall cavity and saturate the insulation, reducing its effectiveness. In severe situations, the insulation and wall structural materials can be destroyed.
For the most convenience and efficiency, consider installing a super-quiet combination vent fan/light. The premium models, usually the most decorative and full-featured, are often the most quiet models too. The newest fans have beveled or frosted glass panels with brightly polished metal or real oak wood trim. They look more like decorative ceiling light fixtures because the air vent inlets are hidden in the trim ring.
The key to efficient operation of a bathroom vent fan is knowing how long to leave it on. If you switch it off too soon, the moisture and odors are not completely removed. If you run it too long, it sucks out excessive conditioned indoor air. The best new models take care of this with built-in automatic humidity and/or motion sensors.
The humidity sensor switches on the bath vent fan and runs it only as long as necessary. It quickly clears excess moisture and then shuts off to save electricity. If the moisture level is not elevated, the
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motion sensor will switch on the light and the fan for only as long as you are in the bathroom. The combination of the two sensors provides effective control.
A model with a motion sensor and night light is a great plus, especially with children. The seven-watt night light uses very little electricity and often provides adequate brightness to use the bathroom at night. If you like more light, activate the motion sensor (most have manual override sensor switches) so that the bright light comes on the instant you enter the bathroom. Some models also offer efficient fluorescent bulbs.
When shopping at your home center store for a bathroom vent fan, you'll notice that most models will look similar. To compare the sound levels, and they vary a lot, check the sound ratings in sones (usually listed on the packaging). Hidden internal features like sound-absorbing scrolls, rubber motor mounts, shape of the air chambers, etc. have a great impact on the sound level.
The quietest small models operate at less than 1.0 sone (the sound level of a quiet whisper). New higher capacity models, rated in cubic feet per minute (cfm) of air flow, are typically somewhat louder, but will still be much quieter than your old one. Any models under 2.0 sones are considered quiet.
Since the sound level is somewhat a function of cfm capacity, it is important to size the fan properly. Also, a properly sized fan will vent the bathroom more effectively. As a rule of thumb, the air flow capacity (cfm) of a bathroom vent fan should be about 10 percent greater than the square footage of the bathroom. For example, a 50 square-foot bathroom needs a 55-cfm vent fan.
Another option to consider for your bathroom is a remote in-line vent fan. The fan motor is located far up inside the attic with a duct running down to an attractive ceiling air inlet fixture. It looks like an ordinary ceiling fan from inside the bathroom. Since the fan motor is mounted in the attic instead of the ceiling, you barely hear it run in the bathroom.
You can use a single powerful remote vent fan to ventilate two bathrooms with a "Y" duct fitting and separate ducts to each bathroom ceiling. Another effective option for one bathroom is to install two air inlets — one over the lavatory and one in the shower.
Write for (or instantly download - www.dulley.com) Utility Bills Update No. 427 - buyer's guide of 12 quiet bathroom vent fan/lights, cfm air flows, sone sound levels, wattages, features and a sizing chart. Please include $3.00 and a business-size SASE to: Jim Dulley, Illinois Country Living, P.O. Box 3787, Springfield, IL 62708.
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 1999 James Dulley
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