There are three types of extractor fan commonly used in the home and all are comparatively easy to install.
Perhaps the most common is the window fan which is fitted in a hole cut in a fixed pane of glass. These fans can be controlled by an integral switch, usually cord-operated, or else by a separate wall-mounted, rocker switch. The installation involves no structural work; just ask your glazier to replace the pane with one in which a hole has already been cut.
A wall fan, controlled by similar switches, is fitted in a hole made in an external wall or in an air brick vent. This sort of fan takes a little longer to install, as a hole has to be made in the external wall However, by installing a wall fan in preference to a window-mounted fan you avoid restricting the view from a window and the inconvenience of having to have that window permanently closed.
There's one other common kind of extractor fan and that's the self-actuating, window-mounted plastic ventilator. But although the easiest to install and cheapest to run - no further expenses after installation - this type is also the least effective.
There are other, more specialized, types of extractor fans such as cooker hoods and timed fans for the bathroom or toilets which are variations on the three main types already described. Cooker hoods either recirculate the air in a kitchen after filtering it, or else extract it. Timed fans in the bathroom or toilet are activated by the lightswitch and are particularly useful when these rooms don't have external walls. Obviously, they will require ducting to enable the air to be expelled outside, but the timed switch poses no extra problems as it's connected up to the light switch when the fan is linked to the lighting circuit. Ceiling-fitted extractor fans are also available. They require an unobstructed space of 300mm (l2in) between ceiling joists, and may also require ducting to an external wall if you have glass fiber roof insulation.
