How to choose a roof fan for mechanical ventilation

Choosing a roof extract fan depends first on the required airflow, expressed in m³/h. Our range spans from 450 m³/h with the TKS 300 roof fan up to 4,200 m³/h with the T40 or the T4048-TRI. In between, the T11 (1,100 m³/h) and the T25 (2,500 m³/h) cover the intermediate needs of an apartment block, a shop or a communal building. The volume of the premises, the number of connected grilles, the duct length and the number of elbows must also be taken into account: ductwork with high pressure losses will reduce the airflow actually achieved compared with the fan's theoretical rating.

The power supply is a second criterion. Most of our roof fans run on single-phase 230 V, convenient for a straightforward connection. The T4048-TRI runs on three-phase 380 V and offers 2 speeds, a real advantage for adjusting airflow to the building's activity without changing equipment. The T25 comes with a speed controller and remains suitable for use with wood-burning stoves.

Roof or wall mounted installation

A roof fan for mechanical ventilation is installed outside the building, on the roof or on an external wall depending on the ductwork layout. That's the whole point of this product: the motor stays outside the premises, away from offices or working areas, which limits noise nuisance indoors. Before ordering, check the configuration of your roof or wall, as well as access for connecting the ductwork.

Roof fans suitable for smoke extraction

The T32, T40 and T4048-TRI roof fans from the Saftair brand are manufactured in France and stated to meet smoke extraction standard C4. A fire rating should never be chosen lightly: if your project requires a specific fire resistance (C4 or F400/120, two distinct and non-interchangeable ratings), please have our team confirm the exact reference and resistance duration before placing your order.

Comparison table of the range

Roof fan or extraction fan box?

The roof extract fan is installed outside the building, on the roof or on an external wall, with the motor exposed on the ductwork. When the motor instead needs to be hidden in a loft space, a false ceiling or a plant room, an extraction fan box will be better suited to your setup. Browse our full range of professional mechanical ventilation systems on the commercial and communal ventilation page.

Points to check before ordering

• The actual airflow required according to the volume of the premises, taking into account the pressure losses in the ductwork (duct length, elbows, any filters): a theoretical airflow is never guaranteed at outlet if the ductwork is undersized.
• The diameter and length of existing ducts, to check compatibility with the fan's connection.
• The power supply available on site: single-phase 230 V or three-phase 380 V depending on the model.
• The type of installation (roof or wall) and access for connection, especially on a flat or pitched roof.
• If a fire rating is required by your project, have the exact reference and duration confirmed (C4 or F400/120) before ordering: these two ratings are not equivalent.

Need help choosing your roof fan?

Let us know the required airflow, the diameter and length of the ducts, the number of elbows, the intended use and whether the fan should be installed on the roof or on a wall. We can then point you towards the model suited to your installation. VentilSoGood supplies the equipment but does not install it: please arrange for a qualified professional to carry out fitting and connection.