Commercial kitchen extraction
Commercial Kitchen Extraction Installation
What does a commercial kitchen extraction installation include?
A commercial kitchen extraction installation covers the whole air path: a canopy sized from the appliances under it, grease separators, ductwork routed to a discharge point with cleaning access built in, a fan matched to the resistance of that route, odour treatment where the discharge needs it, and make-up air to replace what is taken out. It ends with commissioning and a written record.
Do I need extraction in a commercial kitchen?
Yes, by more than one route. The Workplace (Health, Safety and Welfare) Regulations 1992 require enclosed workplaces to have a sufficient quantity of fresh or purified air, and food hygiene law requires food premises to be suitably ventilated. Where gas appliances are used, the Gas Safety (Installation and Use) Regulations 1998 require them to be usable without danger, which normally means a gas interlock proving extraction first. None of those rules gives a number.
How is a system sized?
From the appliance line, not from the room. DW172 publishes an appliance schedule giving an extract coefficient for each appliance, so a char grill and a bain-marie of the same width are calculated differently. The canopy is then set by its overhang on every open side, the duty of what sits under it, and its mounting height. No primary source could be found for a minimum extraction rate, duct gauge or duct velocity, so none appears here. How canopies are sized.
Ductwork routing, and why access panels are designed in first
The route is decided at survey: canopy to a discharge point the building and its neighbours can accept, with as few bends as possible, because every bend adds resistance and collects grease.
DW172 asks for access positioned so that every internal surface can be cleaned. Drawn in at design stage, panels cost very little. Cut into a finished run later they cost far more, and a system without them turns every future TR19 grease clean partial.
Fan selection and where the fan is mounted
A fan is selected against two numbers: the volume the canopy needs to move, and the resistance of the route it moves it through. Chosen on volume alone it underperforms, and the symptom is a kitchen holding smoke while the fan sounds healthy. Mounting at the discharge end, usually roof level, keeps the duct under negative pressure, so a leak draws in rather than pushing grease into the building.
Filtration and odour control
Grease separation happens at the canopy. DW172 calls these grease separators rather than filters, certified to LPS1263, VDI 2052 or equivalent testing. Odour control is separate, driven by where the air discharges and who is near it.
Make-up air, and why most quotes leave it out
Make-up air is the air brought in to replace what the extract takes out. If nobody has designed where it comes from, the building decides: gaps around doors, the dining room, the cellar, a flue.
The result is the faults kitchens live with for years and blame on the fan: draughts across the pass, cooking smells in the restaurant, and extraction below design because the fan is fighting the building.
Commissioning, and what you are handed at the end
Commissioning turns the design into measurements.
| Stage | What it covers |
|---|---|
| Survey | Appliance line measured, duct route traced, make-up air checked. |
| Design | Canopy sized appliance by appliance, access panels drawn. |
| Fabrication | Canopy built in stainless steel, with separators and lighting. |
| Installation | Canopy hung, ductwork run and sealed, fan mounted. |
| Commissioning | Airflow measured, controls proven, record issued. |
The gas side of the interlock is Gas Safe registered work and we do not carry it out. We hand over the ventilation side, measured and proven, for a Gas Safe engineer to sign against.
How long does an installation take?
A canopy replacement reusing sound ductwork is usually a one to two day job. A new duct route, a roof-level fan or an island canopy takes longer, depending on what the survey finds above the ceiling. Most of it runs outside service hours.
Do I need planning permission?
Often, yes, and it is decided by your local planning authority rather than by us. External ductwork, a flue running up an elevation and a new discharge terminal are all alterations to the outside of a building. The answer tightens on a listed building, in a conservation area, and alongside a change of use, which is the usual case when a unit is becoming a kitchen for the first time.
It is worth asking early. Planning is the part of an installation programme that cannot be compressed by working harder, and a discharge point that the planners refuse changes the duct route, which changes the fan.
What does an installation cost?
We publish no installation price. The ranges in circulation contradict each other by roughly a factor of ten, depending on whether the quote covers a canopy swap or a full system, so a number from one end of that spread tells you nothing about your kitchen.
A survey comes first. It is free, and it produces a fixed price against a drawn design. Book a site survey.
Sources
- Workplace (Health, Safety and Welfare) Regulations 1992, regulation 6, ventilation: legislation.gov.uk. Checked 15 August 2026.
- Regulation (EC) No 852/2004 on the hygiene of foodstuffs, Annex II, food premises ventilation: legislation.gov.uk. Checked 15 August 2026.
- Gas Safety (Installation and Use) Regulations 1998: legislation.gov.uk. Checked 15 August 2026.