· Expert Exhaust Cleaning · Compliance · 3 min read
How Often Should a Commercial Kitchen Exhaust System Be Cleaned in Sydney?
Every 3 to 6 months for most Sydney kitchens — but AS 1851 sets the interval by cooking load, not the calendar. Here is how to work out yours.
Short answer: every 3 to 6 months for most Sydney commercial kitchens. Charcoal, wok and high-volume frying kitchens generally need quarterly duct cleaning and monthly filter cleaning. Light-use and institutional kitchens can often extend to 12 months. AS 1851 ties the interval to cooking load and measured grease accumulation, not to a fixed calendar date.
What determines cleaning frequency?
Three things, in order of impact:
- Cooking method. Charcoal, wok burners and deep fryers atomise far more oil than grilling or reheating. Wok cooking in particular pushes grease past the filters and deep into the duct run.
- Daily runtime. A production kitchen running twelve hours loads its system roughly twice as fast as a restaurant running six.
- System design. Long horizontal runs, multiple bends and undersized ducts all give grease more surface to settle on.
Recommended intervals by kitchen type
| Kitchen type | Typical cooking load | Canopy & filters | Duct & fan |
|---|---|---|---|
| Charcoal grill, wok or solid fuel | 12+ hours daily, high grease | Monthly | Every 3 months |
| Fast food / high-volume frying | 10–14 hours daily, fryer-led | Monthly | Every 3 months |
| Restaurant (à la carte) | 6–10 hours daily, mixed | Every 3 months | Every 6 months |
| Club or pub bistro | Peak weekend volume | Every 3 months | Every 6 months |
| Café / breakfast-led | 4–8 hours daily, light–moderate | Every 3–6 months | Every 6–12 months |
| School, aged care or hospital | Scheduled service, moderate | Every 6 months | Every 12 months |
How is the interval actually set?
By measurement. On the first clean we record grease depth at each access point along the duct run. That measurement, compared against the time since the last clean, gives an accumulation rate — and the interval follows from it.
This matters because it works in both directions. A café sold a quarterly package it does not need is being overcharged; a charcoal kitchen on a six-monthly schedule is carrying fire load it should not be.
What does AS 1851 actually say?
AS 1851 is the Australian Standard for the routine service of fire protection systems and equipment, and kitchen exhaust hood and duct systems fall within its scope. It does not name a single frequency for every kitchen. Instead it requires inspection at intervals appropriate to the installation and its use, with cleaning triggered by observed accumulation.
In practice that means: inspect quarterly, clean when the evidence says to, and document both.
What happens if you clean too infrequently?
- Fire load rises continuously. Grease build-up is the leading cause of commercial kitchen fires, and a loaded duct carries fire from the canopy through the ceiling void to the roof.
- Extraction degrades. A 3 mm lining through a 300 mm duct removes measurable cross-section and adds friction. The kitchen gets hotter and smokier before anyone identifies why.
- Insurance exposure. Most commercial policies require cleaning at a stated interval with written evidence. An undocumented system is a declined claim waiting to happen.
What about AS/NZS 1668.1?
Different standard, different job. AS/NZS 1668.1 governs how the ventilation system was designed and installed — duct sizing, fire dampers, discharge location. AS 1851 governs how it is serviced afterwards. Cleaning cannot fix a design fault, which is why we assess against both and report installation problems separately.
Practical scheduling for Sydney venues
- Book the heavy clean before summer, not during it. Rooftop fan motors have the least thermal headroom in January.
- Align fan and duct cleaning. Cleaning a fan under a loaded duct just recontaminates it.
- Set the next service date at the current one, so the certificate never lapses between audits.
Not sure where your kitchen sits? Get a same-day quote and we will measure it rather than guess.
Book compliance & safety cleaning to set your interval from measured grease depth, or get a same-day quote.
