January 2008
Bathroom fans: Strong, silent types
UP, UP, AND AWAY A bathroom fan is designed to be out of sight, anchored in the ceiling between joists, with an exhaust duct that leads to
the outside. All you see is the grille; all you should hear is a faint hum.
Illustration by Trevor JohnstonAlthough an exhaust fan has been a standard part of most bathrooms for many years, people are often loath to use theirs, thinking
it’s too noisy. That’s unfortunate because, as this report explains, it’s important to keep indoor moisture levels down, especially
in newer, more airtight homes. And as our tests of 20 fans show, a good one doesn’t have to be raucous. The best were affordable,
easy to install, and nearly inaudible.
HOW TO CHOOSE
Estimate the air-moving capacity you need. The Home Ventilation Institute, the industry’s trade association, has this sensible rule of thumb for most bathrooms: The fan should have airflow of one cubic foot per minute (cfm) for every square foot of bathroom area up to 100 square feet. For larger bathrooms, the institute recommends a ventilation rate based on the number of fixtures present--50 cfm for each toilet, shower, or bath and 100 cfm for whirlpool tubs. A large bathroom may need two smaller fans, not one large one.
Most fans on the market carry a cfm rating from the Home Ventilation Institute. Our tests show that you can rely on those numbers. Only the bottom-rated fan didn’t come close to its cfm rating.
Look for a quiet fan. We measured each fan’s noise in decibels. The quietest ones whispered. The noisiest produced a noticeable hum.
Our findings track with the industry ‘s noise ratings, which you can use to compare fans. The industry bases its ratings on a sones scale, which represents how people perceive loudness. As the sones number doubles, so does the loudness. Fans we judged excellent for noise typically have an industry rating of 0.5 to 1.2 sones. Fans we judged very good typically have an industry rating of 1.5 to 2 sones. The noisiest we tested are rated at 4 sones.
Mind the drafts. Most fans will try to prevent outside air from entering the room. A few were worse than the norm. Drafts will be most noticeable if the weather is severe in your area.
Seek useful features and accessories. These are common choices:
If you can connect a vent to a clothes dryer, install a ceiling light fixture, and patch wallboard, you have the skills needed
to replace a bathroom fan. A new installation, which means routing the exhaust duct through the ceiling, is more involved.
HOW TO CHOOSE
Estimate the air-moving capacity you need. The Home Ventilation Institute, the industry’s trade association, has this sensible rule of thumb for most bathrooms: The fan should have airflow of one cubic foot per minute (cfm) for every square foot of bathroom area up to 100 square feet. For larger bathrooms, the institute recommends a ventilation rate based on the number of fixtures present--50 cfm for each toilet, shower, or bath and 100 cfm for whirlpool tubs. A large bathroom may need two smaller fans, not one large one.
Most fans on the market carry a cfm rating from the Home Ventilation Institute. Our tests show that you can rely on those numbers. Only the bottom-rated fan didn’t come close to its cfm rating.
Look for a quiet fan. We measured each fan’s noise in decibels. The quietest ones whispered. The noisiest produced a noticeable hum.
Our findings track with the industry ‘s noise ratings, which you can use to compare fans. The industry bases its ratings on a sones scale, which represents how people perceive loudness. As the sones number doubles, so does the loudness. Fans we judged excellent for noise typically have an industry rating of 0.5 to 1.2 sones. Fans we judged very good typically have an industry rating of 1.5 to 2 sones. The noisiest we tested are rated at 4 sones.
Mind the drafts. Most fans will try to prevent outside air from entering the room. A few were worse than the norm. Drafts will be most noticeable if the weather is severe in your area.
Seek useful features and accessories. These are common choices:
- An integral ceiling light is the most common add-on. Two of the Broan fans we tested can be activated by an included humidity
or motion sensor as well as a wall switch. You might also want to connect the fan to a separate automatic timer that’s part
of the wall switch. It costs about $40.
- An easily accessible electrical junction box, to allow wiring of the fan without taking anything apart.
- Adjustable mounting brackets, which provide the most options for positioning the fan between ceiling joists. Most of these
fans have a 4-inch-diameter exhaust outlet, but a few small fans have a 3-inch outlet. If the new fan’s outlet does not match
the venting you already have, you’ll need an adapter; but note that a smaller-diameter duct may restrict airflow significantly.
