In bathrooms and kitchens, overhead exhaust fans are used to pull unwanted airborne particles out of the room and into the atmosphere. When it’s working properly, the exhaust duct is a one-way street to the outdoors. But during the cold weather season, exhaust fans may also making it too easy for frigid air to creep in.
Why Do We Need Exhaust Fans?
In the bathroom, the most important function of your exhaust fan is to draw warm, humid air out of the room when you’re taking a hot shower. When this air lingers, condensation can form on every surface, rotting drywall and contributing to the development of mold and mildew. An exhaust fan that is sized appropriately for your bathroom can even prevent your mirrors from getting too foggy when your shower produces steam.
The fan in your kitchen’s range hood can be a lifesaver if you accidentally release a plume of smoke after burning the roast, or if you just want to help strong cooking smells clear out faster. It will also remove steam from pots of boiling water — protecting the wall near the stovetop — and draw away fumes from lighting the gas range. During the summer, a kitchen exhaust fan can efficiently remove hot air to give your air conditioner a break.
Know Your Stuff
Every exhaust fan system should have a backdraft damper installed where the exhaust duct exits the roof or exterior wall. This may be a factory-installed piece that came with an exhaust fan kit, or it could be a separate part selected by the installer. There are also several different styles of backdraft dampers, and some are more reliable than others.
It’s a good idea to know exactly where your exhaust ducts exit and how your dampers work, because there are several things that can go wrong with them. For example, a windborne twig could get jammed in a hinged damper flap, holding it open even when the exhaust fan is turned off. This would provide a wide-open entrance for cold air, pests and debris.
Over time, dampers will suffer broken parts or the flaps might get rusted and stuck open. It’s a good idea to check these out in early fall and whenever you clean your gutters, and replace them when the time comes.
Even if your damper is in good shape, you may want to consider replacement if you notice abnormally cold air below your exhaust fan. Not all dampers are created equal, and some may allow too much cold air to seep in even when they’re functioning normally. If you’re unsure whether replacing your damper could make a difference, ask an HVAC professional.
And if you need upgrades or assistance with any other element of your heating, ventilation and air conditioning systems, reach out to your local home comfort experts.