The Importance of Bathroom and Kitchen Fans

Bathroom fans are an important part of your home’s ventilation system. They remove odours from your house, which improves indoor air quality. They also remove moisture, which decreases the level of humidity in your house. High humidity can damage building materials and can cause mold growth. Mold may affect your family’s health.

Bathroom Fans: What Should I Look For?

Fan exhaust capacity is rated in litres per second (L/s) or cubic feet per minute (cfm). A normal bathroom needs a good-quality fan that draws 25 L/s (50 cfm). A poor-quality fan won’t exhaust enough air and will be too noisy for regular use. The best fans have sound ratings of 0.5 sones or less and consume about 20 watts. Older units typically run up to 4 sones and 80 watts.

Large bathrooms, or those with bigger fixtures, such as spas, need larger fans. Place the bathroom fan as close as possible to the source of moisture or odour. For in-line fans, as long as the intake grille is properly located, the fan itself does not have to be close to the bathroom. Some bathroom fans have lights or heating lamps. If you choose a fan with integrated lights, look for efficiency. Any fan installed in an insulated ceiling — for instance, if the attic is above the bathroom ceiling — must not leak air and must be rated for use under insulation.

Make sure that exhaust fans, lights and heaters in bath or shower enclosures are rated and approved for wet conditions. Newer units approved for wet conditions may include ground fault protection.

Noise

Noise determines whether people use a fan. Many people won’t use a noisy fan. Select the quietest fan in the size you need. Look for fans labelled “low noise” or “quiet,” and check for the HVI rating. If it is not rated, there is a good chance that it will be noisy. In-line fans, due to their potential remote mounting, can also be very quiet.

Fan Power Requirements and Airflows

There is more to energy efficiency than selecting an energy-efficient fan. Ducting can affect fan performance. Uninsulated, undersized, or droopy flex ducting, ineffective or dirty backdraft dampers and exhaust louvers can cut rated airflow by more than 50 per cent.

To find out if your exhaust fan is drawing air, hold a piece of toilet tissue up to the grille. The exhaust air should hold the tissue tightly to the grille. You could also check the outlet to make sure the air is leaving your house. CMHC has developed a simple test to measure flow and published it as an About Your House fact sheet titled CMHC Garbage Bag Airflow Test.

Controls

Bathroom fans connected to light switches start running when the light is turned on. Often, users turn the light off before all the moisture is exhausted after a bath or shower. An electronic timer, which is usually quieter than a mechanical timer, offers a wide range of settings. Make sure the time instructions are easy-to-understand and the timer is easy to use. You can use motion or humidity sensors, or a combination of both, to control the fan. Controls which allow you to specify operating times or maximum humidity levels are preferable to those where the operation is pre-set by the manufacturer. Use a delayed fan shut-off to keep the fan running for 15 minutes after you leave the room.

Cleaning

Fans create static electricity which attracts dirt like a magnet to the fan and its housing. The dirt can encourage mold growth and restrict air movement. Clean fans, housings, backdraft dampers and exterior flaps seasonally. A typical bathroom fan can be cleaned by pulling down the grille, and unplugging and removing the fan module. Fans in ducts and exterior fans may be difficult to clean.