An extract duct is used to clear polluted air from a room and replace it with fresher outside air. It removes odours, moisture, airborne bacteria and carbon dioxide. It also helps prevent fires and reduces ventilation problems by returning hot stale air to its source preventing smoke & fumes from building up in other rooms & the roof space.

Generally, non-domestic kitchen extract ductwork should be tested to ensure it can pass both Type A (flame) and Type B (smoke) to help reduce the risk of flammable grease spreading from one area into another via ducting or from the roof space into the dwelling. It should also be insulated to avoid internal condensation if the ductwork passes through unheated voids such as MF ceilings.

Optimizing Airflow: Importance of Properly Maintained Extract Ducts

A duct can be either intermittent or continuous – intermittent ventilation turns the extractor on and off at regular intervals to provide constant background ventilation, while a continuous extractor runs continuously at a lower rate in the background. If a ventilation system is not maintained and cleaned regularly it will become contaminated with grease and grime that causes unpleasant odours, can cause asthma and allergies, as well as increasing the risk of fire.

If a new or replacement extractor is fitted and connected to an electrical circuit, a registered electrician should carry out the work and self-certify it in accordance with Part P of the building regulations. If the ducting is being extended or rerouted then the electrician should be certified for electrical installation in a bathroom zone 1 or 2. All extractors must be low voltage (marked SELV) and can only be installed into a ducted system that has been tested to BS EN1366-1 with insulation which delays a temperature rise of 180°C.