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Kitchen extraction - the whole system
A kitchen extraction system is not one thing on one cleaning schedule. It is a chain of parts - canopy, filters, ductwork, plenum, fan - that foul at very different rates, and understanding that is the key to knowing what cleaning the system actually means.
The short answer
There is no single interval for a kitchen extraction system, because it is made of parts that foul at different rates and because cooking intensity varies. Baffle filters need cleaning daily to weekly; the ductwork, plenum and fan behind them build up grease over a longer period and are cleaned on a periodic specialist cycle set by how heavily the kitchen cooks. Cleaning the whole system means addressing the whole chain, and the frequency for the deeper parts is set by fire risk - which is what the TR19 interval bands express.
What the system is
When people ask how often to clean the extraction system, it helps to be clear on what the system is. It starts at the canopy over the cookline, with its baffle filters. Behind the filters is the plenum - the chamber the canopy draws into. From there the ductwork carries the extracted air, often a long run through the building, to the extract fan, which drives the whole thing and discharges the air outside. Each of those - canopy, filters, plenum, ductwork, fan - is part of the extraction system.
The reason this matters to frequency is that these parts do not foul at the same rate. Grease is heaviest at the front, where the filters catch most of it, and what gets past distributes along the ductwork and collects at the fan. So different parts of the same system accumulate grease on very different timescales, and cleaning the system properly means recognising that - not applying one interval to everything, but matching the attention each part needs to how fast it actually fouls.
Different parts, different clocks
The clearest split is between the filters and everything behind them. Baffle filters, taking the first and heaviest grease, need cleaning very frequently - daily to weekly - and this is usually a routine in-house task. The ductwork, plenum and fan behind them foul far more slowly, because the filters have already removed most of the grease, so they are cleaned on a much longer, periodic cycle by a specialist who can reach and properly clean those enclosed parts.
So cleaning the whole system is really two jobs on two clocks. The fast one is the frequent filter cleaning the kitchen does itself. The slow one is the periodic deep clean of the ductwork and fan, which is the specialist extract clean people usually mean by cleaning the system. Neither replaces the other: frequent filter cleaning keeps the front working and slows the downstream fouling, but grease still gets through and builds up in the ductwork and fan, which need their own periodic reset.
What sets the frequency
For the periodic deep clean of the ductwork and fan, the interval is set by how much grease the kitchen produces, because grease accumulation is what creates the fire risk the cleaning controls. A kitchen frying and grilling for long hours every day loads its system with grease far faster than one doing light, occasional cooking, and so needs cleaning more often. The frequency follows the grease, and the grease follows the cooking - so a heavy-use kitchen is on a much shorter cycle than a light one.
This risk-based approach is exactly what the recognised guidance formalises. Rather than one universal interval, the TR19 Grease guidance sets cleaning frequencies by the volume of cooking - light, moderate or heavy use - because that is what determines how fast grease builds to a level that carries fire risk. So the honest answer to how often is: as often as your cooking volume requires to keep grease from accumulating to a fire risk, which is what the use-based interval bands are there to translate into practice.
Why the whole chain matters
The trap is to judge the system by the parts you can see. A canopy with freshly cleaned baffles looks like a clean system, but the grease that has passed the filters over months is out of sight in the ductwork and at the fan - and that is where a lot of the fire risk sits, in a long enclosed run of combustible deposit through the building. A system is only as clean as its worst-neglected part, and the neglected part is usually the bit no one sees.
That is why cleaning the whole system, not just the visible front, is the point. The periodic specialist clean exists precisely to reach the ductwork, plenum and fan that daily cleaning cannot, and to verify they are brought back to a properly clean state. Judging the system by the shiny canopy while grease accumulates unseen in the duct is how kitchens end up compliant-looking and genuinely at risk at the same time - which cleaning the whole chain, on the right cycle, is what prevents.
The takeaway
How often to clean a kitchen extraction system has no single answer because the system has no single fouling rate. The filters need frequent, in-house cleaning; the ductwork, plenum and fan need a periodic specialist clean whose interval is set by how heavily the kitchen cooks. Cleaning the system means covering the whole chain, each part on the clock that suits how fast it fouls.
For the deeper parts, the guiding principle is fire risk: clean often enough that grease never builds to a dangerous level, which for a busy kitchen means a genuinely regular cycle and for a light one a longer one. The recognised way to turn that into an actual interval is the use-based banding of the TR19 Grease guidance. Get the filters onto their fast clock and the system onto its risk-based one, and the whole extraction system stays both effective and safe.
Questions
There is no single interval - the system is made of parts that foul at different rates. Filters need cleaning daily to weekly; the ductwork, plenum and fan need a periodic specialist clean set by how heavily the kitchen cooks.
The whole chain: the canopy and its baffle filters over the cookline, the plenum behind them, the ductwork carrying the air through the building, and the extract fan that drives it and discharges outside. Each part is part of the system.
Because grease is heaviest at the front, where filters catch most of it, and what gets past distributes along the ductwork and collects at the fan. Different parts accumulate grease on very different timescales, so one interval does not fit all of them.
How much grease the kitchen produces, because grease build-up creates the fire risk the cleaning controls. Heavy frying and grilling foul the system faster and need cleaning more often - which is what the TR19 use-based interval bands express.
No. A freshly cleaned canopy can sit above ductwork full of grease that passed the filters over months - which is where much of the fire risk is. A system is only as clean as its worst-neglected part, usually the enclosed run no one sees.
The TR19 Grease guidance sets deep-clean frequencies by cooking volume - light, moderate or heavy use - because that determines how fast grease builds to a fire risk. It is the recognised way to turn the risk-based principle into an actual interval.
We deep clean the ductwork, plenum and fan behind your filters on a cycle set by how heavily you cook - and verify the whole extraction system is properly clean.
