System design

How does a commercial kitchen extraction system work?

A clear guide to capture, airflow, duct resistance, fan duty and replacement air in commercial kitchen ventilation systems.

A commercial kitchen extraction system captures heat, grease, smoke and cooking vapours at the canopy, then moves the contaminated air through filtration and ductwork to a suitable discharge point. The fan, duct route, replacement air and canopy must be considered as one system.

This guide provides general information. Final equipment selection and compliance decisions require a project-specific review.

The five parts of an extract system

1. Capture at the canopy

The canopy needs to project beyond the cooking equipment and create an effective capture zone. Its size and airflow depend on the appliance duty, arrangement and installation conditions.

2. Grease filtration

Baffle filters remove a proportion of airborne grease before it enters the ductwork. The filter arrangement must remain accessible for safe, regular cleaning.

3. Extract ductwork

The duct route carries extract air away from the kitchen. Its size, length, fittings and access requirements affect velocity, resistance, cleaning and fire strategy.

4. Fan selection

A fan should be selected at the agreed airflow and system resistance—not from airflow alone. Manufacturer performance data is used to confirm the operating duty point.

5. Replacement air

Air removed from the kitchen must be replaced in a controlled way. Poorly coordinated replacement air can affect capture, comfort, doors and combustion appliances.

What information is needed for an initial review?

  • Kitchen and building drawings
  • Cooking equipment schedule and fuel type
  • Proposed canopy position and dimensions
  • Possible duct route and discharge location
  • Planning, noise, odour and access constraints
  • Whether the scope is supply-only or supply-and-install

If you have these details, send your drawings for an initial project review.

Project-specific support

Need us to review your kitchen?

Send the available drawings, appliance schedule and known constraints.