Commercial Kitchen Equipment Duty Categories

Commercial kitchen equipment duty categories describe the intensity of the cooking plume a ventilation system must capture. They are commonly expressed from light through medium and heavy to very heavy duty. The category is not simply a description of appliance size: cooking process, heat, grease, smoke, steam, fuel and use all affect the design classification.

Why the classification matters

Equipment duty affects:

  • required extract air quantity;
  • canopy dimensions and exposed-edge treatment;
  • grease-filter selection;
  • particulate and odour-control needs;
  • replacement-air design;
  • fan and duct sizing;
  • noise and energy use;
  • cleaning frequency and fire risk;
  • planning risk at the final discharge.

An incorrectly low classification can leave a canopy unable to capture fumes during peak use. An unnecessarily high assumption can increase fan size, duct space, noise, heating demand and operating cost.

The categories in plain English

Light duty

Generally associated with lower plume, grease and smoke loads. This does not mean “no ventilation”. Heat and moisture can still require effective capture or room ventilation.

Medium duty

Cooking with a more substantial heat or moisture plume and potentially moderate grease generation.

Heavy duty

Processes producing significant heat, grease, smoke or sustained plume loads. Frying and high-temperature surface cooking often drive greater extraction and treatment demands, but the exact classification must come from the current design reference.

Very heavy duty

High-intensity processes with particularly strong thermal, grease or smoke emissions. Some solid-fuel and specialist high-output cooking can create additional combustion, fire and particulate considerations beyond ordinary canopy sizing.

These descriptions are intentionally general. Use the appliance coefficient and classification information in the current BESA DW/172, not a copied online table.

Why appliance names can mislead

“Oven”, “grill” and “fryer” are broad words.

Two ovens may differ because:

  • one is electric and one gas;
  • one is sealed during cooking and one regularly opens;
  • one uses atmospheric burners and another forced draught;
  • one is used for light reheating and another for high-volume roasting;
  • one has a manufacturer condensate hood;
  • one is used for smoking food.

Likewise, a small countertop appliance used continuously can produce a meaningful plume, while a larger appliance used occasionally may behave differently. Design for the intended operation, not appearance.

Build a useful appliance schedule

For every appliance record:

  • manufacturer;
  • model;
  • dimensions and height;
  • fuel;
  • rated input or connected load;
  • cooking method;
  • peak simultaneous use;
  • door or lid opening direction;
  • manufacturer ventilation requirements;
  • clearances and service access;
  • gas COMCAT category where applicable;
  • whether the appliance is planned now or future provision.

Add the menu and production assumptions behind the schedule. A drawing with anonymous stainless-steel rectangles is not a ventilation design brief.

Mixed-duty cooklines

A canopy often serves several appliances with different duties. The design needs to consider the combined plume and which appliances operate together.

Questions include:

  • Is the highest-duty appliance at an exposed canopy edge?
  • Does an oven door open beyond the capture zone?
  • Can mobile appliances move out of position?
  • Will a future chargrill replace a low-duty appliance?
  • Are solid-fuel appliances separated and treated appropriately?
  • Can filters and fire suppression cover the complete active line?
  • Are gas and electric appliances coordinated with the same ventilation controls?

The worst local plume can matter even when the average cookline duty looks moderate.

Cooking duty also affects odour control

An odour-control system is not sized from airflow alone. The cooking style affects particle and gaseous loads.

For example:

  • frying creates grease aerosols and odour;
  • chargrilling can create fine smoke and strong odour;
  • wok cooking generates high heat and rapid plume movement;
  • solid fuel introduces combustion particles and smoke;
  • baking creates heat and moisture with a different contaminant mix;
  • coffee roasting releases oils, smoke and process-specific odours.

Extechnology's discussion of ESP filtration for different cooking styles illustrates why filtration stages must match the process rather than only the duct size.

Solid fuel needs separate attention

Wood, charcoal and other solid-fuel appliances can create high temperatures, sparks, soot, smoke and combustion products. They may require a dedicated flue or extract strategy, specialist materials, clearances and particulate treatment.

Chimflue's commercial flue overview shows how pizza ovens, coffee roasters and bakery ovens create different exhaust conditions. The appliance manufacturer and competent flue/ventilation designer must define the actual arrangement.

Do not add a solid-fuel appliance beneath an existing gas/electric canopy without a full review.

Common classification mistakes

  • copying a category from a similar-looking appliance;
  • using an outdated online table;
  • ignoring peak simultaneous use;
  • failing to identify gas/forced-draught or solid-fuel construction;
  • designing before the menu is agreed;
  • treating future equipment as “someone else's problem”;
  • overlooking steam released on door opening;
  • assuming filtration choice does not affect fan duty;
  • reducing airflow later to solve noise without retesting capture.

Questions for the designer

  1. Which current DW/172 appliance classification/coefficient was used?
  2. What manufacturer and model information supports it?
  3. Which appliances are assumed to operate simultaneously?
  4. What happens when doors or lids open?
  5. How is the canopy sized for exposed edges?
  6. What filtration and pressure drop are included?
  7. How will replacement air avoid plume disruption?
  8. What future changes can the design accommodate?
  9. How will capture and containment be commissioned?
  10. Which changes require redesign?

Make the equipment schedule the source of truth

The KIG 317 Commercial Kitchen Installation Guide helps project teams connect the equipment schedule with canopy, utilities, gas, workflow and maintenance before installation.

Sources and further reading

This article explains the concept and does not reproduce DW/172's protected appliance schedules. A competent designer must classify the exact equipment using the current specification and manufacturer data. Last reviewed: 13 August 2026.