Extractor fans pull damp air from the bathroom and expel it outdoors, keeping the bathroom dry and preventing mould and other problems caused by moisture buildup. Extractor fans generally are installed in a wall or the ceiling. If your bathroom has an existing ceiling light or fan and an unfinished attic above it for access, you can install the extractor fan yourself. Use the same wires in the circuit that feed the existing fixture, and control it with the same wall switch.
Turn off the power to the ceiling light or fan at the home's main electrical panel.
Remove the mounting screws that hold the electrical box to the floor support beams (joists) on both sides of the electrical box. Remove the box, leaving a hole on the floor. The bathroom will be visible below.
Stretch the vent hose from the extractor fan kit to the exterior wall. Trace the shape of the hose on the wall with your pencil. Cut out the marked area to create an exhaust hole for the hose. Mount the hose to the wall with the provided screws.
Go back down into the bathroom. Set the fan's vent cover over the new opening you cut in the ceiling, installing it as directed - some models require screws, others hook on. Turn the power back on at the electrical panel.