Many people don’t realize that bathroom exhaust fans are an important part of your home's ventilation system. They are often used to eliminate foul odors and to clear condensation off mirrors, but their most important function is to remove moisture. Excess moisture can cause structural damage and rotting of walls and ceilings. But it also encourages the growth of molds, mildew, bacteria, dust mites and insects, which can be detrimental to your family's health. An efficient exhaust fan can control these allergens and even lower air-conditioning costs by dehumidifying your house.
Your current fan may be ineffective
If you live in an older home, there is a good chance that your bathroom exhaust fan is too noisy, moves very little air, is not energy-efficient, uses high-wattage lighting and may cause backdrafting of combustion appliances - and therefore should be replaced. Newer fans are quiet, energy-efficient and more effective at moving air and removing moisture.
A simple test
Here's a simple test to see if your exhaust fan is drawing air. Hold a piece of toilet tissue up to the grill of the fan. A properly working fan will hold the tissue tightly to the grill. And to make sure the air is leaving your house, place the open end of a large plastic garbage bag over the exhaust hood outside. When the fan is turned on, the bag should inflate within seconds.
If your current fan is rated less than 50 CRM (cubic feet per minute), it should be replaced with a stronger one. For bathrooms up to 100 square feet (assuming eight foot ceilings), the HVI (Home Ventilating Institute) recommends that an exhaust fan provide 1 CFM per square foot to properly ventilate the bathroom. Larger bathrooms, or those with bigger fixtures such as steam rooms, hot tubs or saunas, need larger fans. Also, the longer the ductwork to the outside, the stronger the fan needs to be to draw the moisture through.
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HVI sets the standard
When selecting an exhaust fan for your bathroom, choose the quietest, most energy-efficient fan available for the size you need. Research has shown that many people just won't use a noisy fan. Look for HVI ratings on the packages for noise and energy efficiency to compare between models. Better fans have sound ratings of 0.5 sones or less and consume about 20 watts, while older units typically run up to 4 sones and 80 watts. If there is no HVI rating there is a good chance that it will be noisy.
A better fan can save you money
A fan suitable for continuous use, with replaceable parts and permanent lubrication is your best choice. And it is usually best to avoid fans with 3-inch exhaust ports and ducts, in favour of larger ones.
You will pay more for a better fan, but...you can't put a price on your family's health.
You will pay more for a better fan, but more efficient models can save you money in the long run. And you can't put a price on your family's health.
Your HVAC contractor knows the codes
Most building codes require either a vent fan in the bathroom or a window that opens. Builders have typically chosen the easier and cheaper option of installing a window. But problems may arise if the window isn't opened during a bath or shower, which is often the case during the colder months. As a result, some building codes now require a fan which starts when the light is switched on. Your HVAC (Heating Ventilation and Air Conditioning) contractor should be familiar with local codes, including required venting and insulation, and installation procedures to dampen vibration noise.
