27 Aug 2026 · Maintenance
The condition of a commercial kitchen exhaust system between contractor visits is decided by daily habits, not by the contractor. The highest-leverage ones: wash baffle filters nightly and refit them the correct way round so they drain to the gutter; never run the cooking line with filters removed; empty grease gutters and cups before they overflow rather than after; start the fan before cooking and leave it running through cool-down; and keep a short written log of who did what and when.
A kitchen exhaust system gets professional attention a handful of times a year. The rest of the time — which is to say almost all of the time — its condition is decided by the people working underneath it.
That is not a complaint about kitchen teams. It is an observation about where the leverage actually sits. Two kitchens with identical equipment, identical menus and identical cleaning contracts can be in completely different condition when the access panels come off, and the difference is almost always a handful of daily habits.
None of what follows requires equipment, training or extra staff. It requires somebody to own it.
Everything else in this article is secondary to this one point: the filter is the only thing standing between airborne grease and your ductwork.
Grease that the filter catches is a sink job. Your own team can deal with it, tonight, for nothing. Grease that gets past the filter goes into the duct — where nobody in the kitchen can reach it, where it accumulates out of sight, and where removing it means a contractor, access panels and a closed kitchen.
Every gram you keep on the filter is a gram that is not in the duct. That is the entire economics of kitchen exhaust upkeep in one sentence.
Baffle filters are built to be pulled out and washed as routine. In a busy Singapore kitchen that generally means nightly, not weekly. If you are not sure what you have fitted, our comparison of baffle versus mesh filters covers the difference and why it matters.
This is the mistake we see most, and it is invisible from the floor.
A baffle filter works by forcing the air to change direction sharply, so grease droplets — being heavier than air — cannot follow the turn and strike the baffles instead. They then run down and drain, and the filter is built to drain in one direction, towards the grease gutter.
Put back upside down or reversed, the filter still looks perfectly normal in the hood. It still catches grease. But it drains the wrong way, so grease collects where the design never intended it to sit, and in time it finds a route out — down the front of the hood, or onto the cooking surface below.
Whoever refits the filters should know which way is up. It takes one demonstration, once.
It nearly always happens the same way. Filters come out for washing, service starts earlier than expected, and the line fires up with empty filter frames.
A single service period cooked without filters puts more grease into the ductwork than weeks of normal operation. There is nothing at all in the airstream to intercept it.
The practical fix is not discipline, it is a second set of filters. One set in the hood, one set drying. There is then never a moment when the honest answer to "can we start?" is no. This is a small, one-off cost that removes an entire category of problem permanently.
Hoods have a gutter or a cup to collect what drains off the filters. Emptied on a schedule, this is a two-minute job. Left until it is full, it overflows — and what comes out lands on the cooking line, or runs down the outside of the hood, or drips at the worst possible moment.
Put it on the closing checklist with a frequency that suits your volume, and check it more often during periods of heavier frying.
The fan should be running before cooking starts, and should stay running after the line shuts down.
The second half of that is the part that gets skipped. When the last order goes out, the surfaces, the oil and the equipment are all still hot, and they carry on producing vapour for a considerable time. Switching off the fan at that moment sends all of it into the kitchen and up into the ceiling void rather than out through the system.
It is one of the cheapest improvements available: change nothing except when somebody presses the switch.
An exhaust fan can only take out what is replaced. If replacement air is short, the kitchen goes into negative pressure — staff feel hot and stuffy, doors get heavy, and the hood stops capturing properly at exactly the point where it matters.
The instinctive response is to prop open a door. That does let air in, but through an uncontrolled opening, and it can drag airflow across the room in a direction that pulls smoke away from the hood rather than into it.
Door-propping is a symptom worth reporting. If it is happening every service, the kitchen has a make-up air problem, and that is a design question rather than a housekeeping one — see make-up air and air balancing.
Your staff are under the hood every day and will see these long before anyone else does. Any of them is worth passing on rather than working around:
Several of these are early-stage versions of problems that are much cheaper to address early. Our note on the signs a hood is overdue for a deep clean goes into what each one usually means.
A clipboard by the back door with the date, who washed the filters, when the gutter was emptied, and a blank line for anything odd.
It sounds trivial and it changes two things. It makes scheduling the next professional clean a matter of evidence rather than guesswork — the interval that suits a kitchen is a property of that kitchen's menu and hours, not a number copied from somewhere else, and our note on how often cleaning is actually needed explains why. And it means that when anybody asks how the system is maintained, you have an answer with dates on it rather than an assurance.
Filters, gutters, hood surfaces, switching discipline and reporting: the kitchen's. Ductwork, fans, access panels, the parts of the system nobody can see: ours. A team doing the first list well does not eliminate the second — it makes it cheaper, more predictable, and far less likely to arrive as an emergency in the middle of service.
Every cooking line is different, and a routine copied from another restaurant usually fits badly. Tell us what you cook and how long you run, and we will tell you what the daily list should be and how often the system behind it genuinely needs attention. Our kitchen exhaust cleaning page covers what a professional clean includes, and what a maintenance contract should cover sets out how the two fit together.
WhatsApp us on 8989 2833 and we will come back to you with a routine that fits your kitchen.
We design, clean, repair and maintain commercial kitchen exhaust systems across Singapore — on 24/7 standby.