Exhaust fans can have different uses in different rooms.
In the kitchen where boiling water and cooking produces steam, the cooling steam turns into water that can cause condensation on walls, ceilings and around windows. When this is happening on a daily basis, especially during winter, mould and mildew can begin to form which can have an unpleasant odour but can also be harmful to your health.
In some cases condensation can seep into cracks and cause structural rotting and costly repairs.
If you don’t have a rangehood above your stove, an exhaust can be fitted directly above and vented to the outside. Many older houses don’t have exhaust fans fitted or the fans that they have can be underpowered.
Laundries and bathrooms also benefit from one exhaust fan to get rid of damp air before it condenses. Tumbler dryers that are not vented outside and steamy showers can produce large amounts of condensation.
For an exhaust fan to be effective it needs to be powerful enough to expel humid air from the room where it is installed. Fans have a rating for air movement which is measured in CFM or cubic feet per metre.
To work out the size of the fan you need to calculate the volume of the room. To do this you multiply the L x W X H and them multiply the number of air changes you need.
For example:
In a bathroom with a shower 15-20 air changes per hour.
So if you had a room 3 x 3 x 3 x 15 you would need the fan to move approximately 405m3 per hour.
A well ventilated home could be less costly to heat as well as being a healthier place to live.
