Efficient ventilation removes odors, pollutants and vapor-laden air trapped inside a home before they can cause any damage, harm to you or your house or discomfort. Condensation occurs as moist, warm air comes in contact with cold surfaces. It is easily visible on glass, walls or ceilings, but it can also form on carpets and curtains. Damp surfaces may decay over time, and the resulting mold and mildew can cause an unhealthy living environment. Insulation, double-glazing and heating can all lessen condensation, but good channels for ventilation and the free flow of air are required.

Health and Safety

When installing a fan, make sure that the extracted air is replaced by fresh air — especially in a room containing a fuel-burning appliance. Failure to provide fresh air can cause a fatal buildup of carbon monoxide in a room. Fuel-burning appliances should be regularly checked and serviced. If you have any doubts about how to ventilate an appliance, get professional advice before proceeding and install carbon monoxide detectors.

Static Ventilation

A simple hole, usually at the top or base of a wall, with grilles to let air in or out, provides static ventilation. Some interior grilles can be closed, but others are fixed open for constant airflow. Static ventilation is mandatory in rooms with a fuel-burning appliance, and is often used for venting clothes dryers. Unused chimneys also need static ventilation to circulate fresh air and prevent discoloring damp patches from appearing on the chimney breast. "Trickle vents" in window frames provide ventilation even when the windows are closed.

Exhaust Fans

You can ventilate most kitchens and bathrooms with a fan carrying air a short distance through a wall (an axial fan). Wall- or ceiling-mounted fans have their electric components directly behind a grille, and must not be used within reach of water. To ventilate a shower cubicle, use an in-line fan, which is installed with a length of ducting between the grill and the electric parts. Some kitchen fans are built into a cabinet or hood. When choosing a fan, consider the sound it makes (you may want a "low noise" fan for an attached bath), its power and the manufacturer's advice for a specific fan's use. Most can be wired into the lighting circuit to run when a light is on (usually with a timer so that it continues for a while after the light is switched off), or operated separately with a pull-cord.

Bathroom Exhaust

Position the fan on the ceiling. If you have a shower stall, install the fan near the shower. Ensure that you have the correct power supply, and follow the wiring and safety instructions closely.

Exhaust fan with light (Image 1); Exhaust fan with blades and electrics directly behind grill (Image 2)

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DK - Do It Yourself Home Improvement © 2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement © 2009 Dorling Kindersley Limited