How to select a Domestic Toilet Extractor Fan
Legislation indicates a toilet should extract air at a rate of 10 Litres a second (Part F), as you can imagine Toilets come in all sizes so how effective the 10L/S rate will be depends on your Toilet size, we would suggest an acceptable extract rate is a minimum of 10 air changes an hour, to check if 10L/S or 10 air changes an hour is required for your Toilet firstly you need to measure the size of your Toilet, the examples below have the room measurements in Metres.
A Toilet for the purposes of this guide is a room where a toilet and small wash basin is housed.
If this room includes a bath or shower or both please use our bathroom guide..
Let's say the length of your Toilet room is 2 metres long, with a width of 1 metre, and the height is 2.4 metres. That would be: 2 x 1 x 2.4 = 4.8m3 (the volume).
For a Toilet we recommend 10 air changes an hour, or a minimum of 22m3 an hour (or 6 litres a second). In this example the amount of air that should be extracted from the Toilet is:
• 4.8m3 (the area of the Utility Room)
• x 10 air changes an hour
• = 48m3/hr
This is above the minimum we recommend of 22m3/hr.
So in this example the fan required for a Toilet 2 metres x 1 metre x 2.4 metres is:
• 48m3/hr or 14 litres a second
Most domestic fan manufacturers publish the fan performance in m3/hr or litres per second (l/s).
The only thing left to consider are:
• Extra functions e.g. Back Draught Shutters, Run On Timer, Humidity Sensor, Passive Infra-red (PIR) Sensor
Important Note - Building regulations state "in a room with no openable window, an intermittent extract fan should be used with a run on facility set to a minimum of 15 minutes."