Bathroom ventilation fans

Bathroom ventilation fans are absolutely essential in preventing build up of condensation. We are all familiar with the black condensation marks that build up on ceilings and on walls.

The problems with condensation had been made much worse by the fact that most of us now have fitted showers. Preventing condensation build up is extremely easy by using a bathroom extractor fan.

When you install bathroom ventilation fans or get somebody to install one for you make sure it is vented to the outside. I have been to many installations where the fan is just fitted in the ceiling and vents into the loft space, A definite no.

If you are purchasing the fan yourself you will first need to decide which size you need. This is extremely easy; just measure the dimensions of the room as follows.

Length x Width x Height

3 metres x 2.5 metres x 2.5 metres = 11.25 cubic metres.

The recommendations for a bathroom are 6 to 10 air changes per hour.

Based on 10 air changes per hour you would need a fan that will extract 112.5 cubic metres per hour. (11.25 cubic metres x 10)

If the fan is sized in cubic metres per second divide the room size by 3600 (No. Of seconds per hour) i.e. 112.5 = .031 cubic metres per second.

Some bathroom ventilation fans manufacturers use litres per second for their fan sizes, if this is the case use the following formula.

Multiply the no. Of cubic metres per hour x .277. Using the above example 112.5 x .277 = 31.16 litres per second.

If the bathroom contains a shower upgrade the number of air changes per hour to 15 – 20.

There are a number of different ways to control bathroom ventilation fans:

Using a pull switch to turn of the fan, this can be fitted with a run on timer to keep the fan running after it has been switched off. If you elect for this option you will need just a fixed live neutral and earth connection to the fan.

Using a humidistat, which will switch the fan off and on depending on the humidity levels. The power supplies will be the same as above.

The most popular way is to install a fan without a pull switch and operate it by the bathroom ceiling light switch. The fan will have run on timer that will keep the fan running for a set period of time after the bathroom light is switched off. This will ensure that the bathroom is purged of bad smells or clear moisture from the air. The wiring for this will need a switched live supply from the pull switch, a petmanent live plus neutral and earth.

Bathroom fans can also be controlled using a PIR (Passive Infra Red Detector), which will switch the fan on when somebody enters the room and switches it off when they leave. This type of fan is also available with a run on timer.

ImportantIEE Regulations (U.K.) require that a conventional mains voltage fan in a bathroom or shower must be located where it cannot be touched by a person using the bath or shower and well away from any water spray.

Alternatively, there is a range of 12-volt S.E.L.V. (Safety Extra Low Voltage) fans, which are specifically designed for the safe ventilation of toilets, bathrooms and shower rooms and can be fitted within the splash area with absolutely no risk of electric shock.

For other areas of a house the recommended ventilation rates:

In Shower Area 15 - 20

Bathroom & Shower Rooms 15 - 20

Bathroom 6 - 10

Bedrooms 2 - 4

Halls & Landings 4 - 6

Kitchens 10 - 20

Living & Other Domestic Rooms 4 - 6

Toilets - Domestic 6 - 10

Utility Rooms 15 – 20

John Bradley Engineering Services Ltd Is based in the North East of England working from Teesside and covering the Hartlepool, Darlington, Newcastle, Sunderland and North Yorkshire Moors areas. For all your ventilation requirements

Other areas of the country would be considered depending on the type of contract and availability.