Technical Support - Ventilation

SELECTING THE CORRECT FAN

How much ventilation is required?

This depends on:

• Size of Room
• Amount of Use
• Type of Room
• Existing Regulations

Builing Regulations say that mechanical ventilation must provide at least 3 air changes per hour in sanitary accommodation and must also run for at least 15 minutes after the room has been vacated.

Bathrooms require 54m3 (or 15 l/s) when in use.
Click here to view figures.

How to Choose the Correct Extract Fan

Effective ventilation,conforming to Building regulations, depends on the selection of a fan or fans of the correct size and capacity. To do this, you need only consider:

a) The cubic capacity of the area to be ventilated.
b) The required number of air changes per hour. Multiplying the cubic capcity by the number of air changes determines the optimum fan capacity required.

Note:
To convert feet to metres x .3048
To convert metres to feet x 3.28

Click here to view examples

Fans Used with Ducting

If fans are used with ducting,it is important to remember that long lengths of ducting will reduce the fan's performance.

As a rule, when long lengths of ducting are required, Centrifugal Fans need to be selected.