Reopening After a Long Closure: What to Check on the Kitchen Exhaust Before You Cook

Pictured above: a clean hood from our project archive (Stirling Steaks, Capitol), baffle filters seated edge to edge, with the fire suppression nozzles and a sprinkler head on the canopy above them. That is what you want to see before the first burner is lit after a closure: every filter in place, nothing hanging loose, every nozzle where it was commissioned.

A kitchen that has been shut for weeks does not reopen the way it closed. The renovation finished late, the unit sat empty between operators, the outlet went dark for the festive break, or the owner simply paused trading for a month. Then the date is fixed, the staff are rostered, the food order is in, and the exhaust is the one system nobody thinks about until the first busy service fills the kitchen with smoke or the fan does not start at all.

The exhaust is not like a fridge that you plug back in and walk away from. It has a motor and belts that have not turned, a duct that has been sitting with whatever grease was in it, a roof fan that has been out in the rain, and on most cooking lines a fire suppression system that may have been knocked, isolated or simply left unserviced while the doors were shut. Here is what to check, in the order that saves you money, before you cook again.

Why a system that worked before the closure may not work after it

Nothing in an exhaust system improves by sitting still. The common ways a stopped system lets you down:

• The grease did not go anywhere. If the hood, filters and duct were not cleaned before the doors closed, the grease that was in them is still there, and older grease is harder, not softer. A closure is not a clean.
• The fan has not turned. Belts, bearings and the motor have been idle. A fan that ran quietly before can start with a squeal, a knock or a trip, and a belt that was already worn is the likeliest thing to give out in the first week back.
• The outside was not idle. A roof or facade fan has been through weeks of Singapore rain with nobody watching. Water can collect where grease collects, and a seal that was marginal can now be letting water in, as we set out in kitchen exhaust after heavy rain.
• Pests moved in. A warm, dark, greasy hood and duct with no heat and no noise for a month is exactly the kind of space pests look for. The hood void and the plenum behind the filters are where they tend to be found, which is why what lives in the hood is worth reading before you reopen, not after an inspector finds it.
• Somebody worked around it. If the closure was for renovation, the hood may have had other trades on ladders under it for weeks. Filters get taken out and stacked in a corner. Nozzles get bumped. Blow-off caps go missing. Dust from the works gets drawn into the hood, and panels get switched off at the board and never switched back on.

None of this is exotic. It is simply what happens to a mechanical system that nobody has looked at for a while, in a building where other people were working.

Step 1: clean first, if it was not cleaned before closing

The first question is not "does the fan run" but "when was the system last cleaned, and did anyone clean it before the doors closed". If the answer is no, or nobody knows, book the clean before reopening, not in the first week of trading.

The reasoning is simple. A duct carrying old grease is a fire risk the moment the first wok or fryer starts, and a kitchen in its opening weeks is the kitchen most likely to be pushing the line hard while staff are still finding their feet. Most commercial kitchens need cleaning every one to three months, with heavy wok, grill and deep-frying lines often needing monthly attention. If a closure has pushed you past that interval, you are already overdue on day one.

A closure also gives you something you rarely get in a trading kitchen: an empty space and time. That is the easiest possible moment to have the hood, filters, accessible duct and fan cleaned properly, with nobody waiting to cook. Our servicing checklist sets out the ten items a proper service covers, from the hood interior and the baffle filters to opening the fan and degreasing the housing and impeller blades.

Step 2: check the fan and the drive before you trust it

Whether or not the system was cleaned, the mechanical side needs a look before the kitchen depends on it. On our servicing checklist, fan mechanicals and the motor are separate lines for a reason: bearings, belts, vibration and balance are how small wear gets caught before it becomes a mid-service breakdown, and motor condition and connections are the most common cause of a kitchen-down emergency.

What that means in practice for a reopening:

• Run the fan with nothing cooking. Switch the exhaust on at least a day before opening and let it run. Listen at the hood and, if anyone can safely get to it, at the fan. A new squeal, a rhythmic knock or a rattle that was not there before the closure is a reason to call now, not after it fails on a Friday night.
• Watch the control panel. If the fan trips, will not start, or starts and stops, note exactly what the panel shows before anyone resets it repeatedly. Commercial kitchen ventilation troubleshooting sets out what to record so the first visit fixes the right part.
• Check the speed control if you have one. A variable speed drive left at a low setting for quiet running during the works, or reset after a power cut, can leave the fan turning far slower than the line needs.
• Check that make-up air is running too. Exhaust only works when replacement air can get in. If the make-up air fan was switched off during the closure, or its grilles were covered up during painting, the kitchen goes negative, doors pull shut and capture at the hood falls away.

If a belt, bearing or motor does need replacing, it is much better to find out with a week to go than with a full dining room. We stock motors, fans and fan parts in-house, which is what makes a same-visit repair possible, but it is still a visit you would rather have before opening day than during it.

Step 3: put the hood back together properly

This is the step that gets rushed, and it is the one that matters most to the first service.

• Every baffle filter in, seated, no gaps. A missing filter, or one sitting crooked, is an open path for grease straight into the plenum and the duct. Count them against the number of slots.
• Filters in the right way round. Baffle filters are designed to drain grease in one direction. Put in upside down or back to front, they drain the wrong way.
• Grease collection empty and in place. If there is a grease cup or trough on the hood, check it is there, empty and fitted.
• Lights and covers intact. Broken light covers under a hood let grease and heat into places they should not go.
• Nothing stored on or in the hood. Renovation leaves things behind. Check the top of the canopy and the space around it.

Step 4: the fire suppression system, before any flame

If there is a fire suppression system over the cooking line, treat it as the one item that must be right before anyone lights a burner. A suppression system is only ever judged in the seconds it has to work, and a closure is exactly the period when it can be disturbed without anyone noticing.

The points a proper suppression service covers are the ones to think about after a closure:

• Nozzles and blow-off caps. Are the nozzles still aimed at the appliances they were commissioned for, and are the caps on? After renovation, a bumped nozzle is easy to miss from the floor.
• Fusible links and detection. Intact, in position, and not coated in grease or dust from the works.
• Cylinder pressure. There needs to be charge behind the nozzles.
• The gas and electrical shut-off interlock. If the gas or power to the line was isolated during the closure, check the interlock was reinstated properly, not bypassed to get the kitchen running.
• The manual pull station. Visible, unobstructed and known to the staff, especially new staff.
• The service date. If the scheduled service fell during the closure, it did not happen. Book it.

If the cooking line itself changed during the closure, with appliances added, swapped or moved, the suppression coverage needs reviewing against the new line, not just re-checked against the old one. Adding cooking equipment to an existing kitchen hood explains why. Our fire suppression maintenance page sets out what a service visit includes, and we service systems we did not install.

Step 5: the first cook, done deliberately

Once the system is clean, running and put back together, do not make the first real test a full dinner service. Run a short cook on the heaviest appliances, the wok range, the fryer or the grill, with the exhaust at its normal setting, and watch the hood.

• Is smoke and steam going up into the hood, or rolling out at the front and the ends?
• Is there any smell of hot dust or burning from the hood or the duct?
• Does the kitchen feel the way it did before the closure, or hotter and stuffier?
• Do the doors between kitchen and dining room behave normally?

A little dust smell on the very first run after renovation can happen. Smoke escaping the hood, a smell that keeps building, or a kitchen that never clears are not first-day quirks. The exhaust is running but the kitchen is still smoky works through what to check when the fan runs but capture does not.

Keep the paperwork straight

A reopening is also the moment your records reset in the eyes of anyone who asks. If the last clean was before the closure, the next one is due by the clock, not by the reopening date. Get a dated service report with before-and-after photographs for any clean done before reopening, and keep it with the suppression service record. That is the evidence you show NEA, SCDF, your landlord or your insurer, and after a closure it is the only thing that shows the system was looked at rather than simply switched back on.

If the unit has changed hands during the closure, you are in a different situation: you are inheriting someone else's system and history. Taking over an F&B unit covers what to check before you sign.

What to have ready when you call

• How long the kitchen has been closed, and why (renovation, break, change of operator).
• When the hood, filters and duct were last cleaned, and whether that was before the closure.
• Whether the fan has been run since, and whether it tripped, squealed or would not start.
• Whether there is a fire suppression system over the line, and when it was last serviced.
• Whether the cooking line changed during the closure.
• Your reopening date.

The short version

• A closure is not a clean. Old grease is still in the duct, and it is harder than it was.
• If the system was not cleaned before closing, clean it before reopening, while the kitchen is empty.
• Run the exhaust and make-up air for a day before opening. Listen, and watch the control panel.
• Count the baffle filters back in, the right way round, with no gaps.
• Check the fire suppression system before any flame: nozzles, caps, links, cylinder, interlock, pull station and service date.
• Do a short deliberate cook on the heaviest appliances before the first full service.
• Get a dated report. It is your evidence the system was checked, not just switched on.

Reopening soon? WhatsApp BC Air on 8989 2833 with your location, how long you have been closed and your reopening date, and we will tell you what needs doing before the first service. What a clean covers is on the kitchen exhaust cleaning page, mechanical and motor work on the repair page, and scheduled servicing on the maintenance page. Scope and pricing follow an inspection.

Related reading: kitchen exhaust cleaning night: what to prepare and check · kitchen exhaust after heavy rain · commercial kitchen ventilation troubleshooting