Bathrooms
Require mechanical extract ventilation at a rate of 54m3/h (15 l/s)

Toilets
(Without Openable Window)
Require mechanical extract ventilation at a rate of 22m3/h (6 l/s) If above rooms do not contain a window which opens, a 15- minute over-run timer is required

Kitchens
Either
108m3/h (30 l/s) by cooker hood or fan over hob under humidistat control Or 216m3/h (60 l/s) elsewhere
If above rooms do not contain a window which opens, a 15- minute over-run timer is required

Utility Rooms
Require Mechanical extract ventilation at a rate of 108m3/h (30 l/s)
If above rooms do not contain a window which opens, a 15- minute over-run timer is required

Non Domestic Buildings
Domestic type kitchens, bathrooms and toilets require fans similar to those for domestic buildings. Occupied rooms such as rest rooms require an extract rate of 29m3/h (8 l/s) per person or 58m3/h (16 l/s) if smoking is allowed

Alternative Approach
To comply with B.R.E. Digest 398 (continuous mechanical ventilation in dwellings). This requires a ventilation rate of 0.5 air changes per hour based on the whole house volume Background ventilation required e.g. Trickle vents or air-bricks 4000mm 2 typically located 1.75m above floor to prevent draughts. Silavent has a full range of products to comply with Scottish Building Regulations Part K.

AXIAL OR CENTRIFUGAL ?

Axial

Axial Fan

These fans are designed to move air over short distances only, and are therefore suitable for window fixing or through wall application. They are not suitable for ducting runs in excess of 2 metres

Centrifugal

Centrifugal Fans
These fans are designed to move air over longer distances, and will perform well against the resistance presented by ducting and grilles.