EC Cleaners Network · Kitchen Extract Problems
If smoke or cooking fumes are escaping from the canopy, the system is not capturing the cooking plume as effectively as expected.
The cause may be contamination, blocked filters, insufficient extract volume, poor replacement air, fan performance, airflow disturbance, changes to cooking equipment or a wider ventilation issue. Start with the symptom and the recent history before deciding what work is needed.
When and where is the smoke escaping?
Send the site location, the affected cooking equipment, when the problem occurs and anything that changed before it started. Include the latest cleaning or ventilation report, photographs and video where safe and practical.
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Why might smoke stop clearing from a commercial kitchen?
A commercial kitchen canopy needs to capture the heat and fumes rising from the cooking equipment and move them safely into the extract system. If smoke is escaping into the room, the capture process is not working as intended.
HSE guidance says the canopy needs to be suitable for the cooking equipment, positioned close enough to the source and provided with enough extraction to minimise fume spillage. It also says airflow into the canopy should be uniform and appropriate for the appliances and the overall room ventilation rate.
Smoke spillage tells you there is a capture problem. It does not tell you the cause on its own.
Read the parent guide to commercial kitchen extraction problems →
Common reasons smoke can escape from the canopy
Insufficient extract volume
The system may not be moving enough air to capture the cooking plume under the current operating conditions.
Blocked or heavily loaded filters
Filters that are heavily contaminated can restrict the airflow entering the extract system and reduce effective capture.
Grease contamination in the extract route
Heavy contamination can affect system efficiency and may contribute to reduced airflow where internal surfaces or components are heavily loaded.
Insufficient replacement air
Air removed from the kitchen has to be replaced. Poor make-up air can affect the way air moves towards the canopy and can reduce effective capture.
Fan or control problem
The fan may be running at the wrong duty, affected by a control issue or no longer delivering the expected performance.
New or changed cooking equipment
A different appliance or more intensive cooking process can produce a larger or hotter plume than the system was previously required to capture.
Air movement across the canopy
Strong draughts or poorly arranged supply air can disturb the rising cooking plume and pull fumes away from the canopy opening.
Could cleaning solve the smoke problem?
Cleaning may be relevant where filters, canopy sections, ductwork or fan components are heavily contaminated. HSE warns that fat residues and blocked air inlets can reduce ventilation efficiency and increase fire risk.
The condition of the system still needs to support that conclusion. Cleaning will not correct every airflow, control, fan or design issue, so the contractor should not be asked to treat smoke spillage as a cleaning-only problem by assumption.
Why replacement air can affect canopy capture
The air extracted from a commercial kitchen needs to be replaced. HSE guidance says make-up air can be provided by mechanical or natural means, depending on the installation, and that it should not interfere with the performance of the ventilation system.
Replacement air that is inadequate, poorly positioned or too forceful can change the airflow pattern around the cooking equipment. This can make it harder for the canopy to capture smoke and fumes consistently.
Do not treat replacement air as a comfort-only issue. It can affect capture, ventilation performance and, where combustion appliances are involved, safe operation.
Has the cooking equipment changed?
A ventilation system that worked acceptably for one kitchen layout may not perform the same way after equipment is replaced, moved or added. The cooking plume can change because of appliance size, heat output, fuel type, cooking process or increased production.
HSE guidance says kitchen ventilation design should take account of cooking load, the amount of equipment used and the kitchen layout. BESA’s DW/172 is the recognised industry specification for commercial kitchen ventilation design, installation and maintenance.
What if the fan is running but smoke is still escaping?
A running fan only confirms that the fan appears to be operating. It does not confirm that the system is delivering the required extract volume or that the canopy is capturing the plume effectively.
The investigation may need to consider fan duty, controls, filters, duct restrictions, replacement air, canopy position and the current cooking load.
Look at the whole extraction route
Smoke seen at the canopy can be influenced by problems elsewhere in the system. The extract route may include filters, canopy, plenum, ductwork, risers, fan, discharge and the access needed to inspect and maintain those parts.
Historic EC Cleaners project imagery illustrates a commercial kitchen canopy and extraction environment. It is not presented as a current diagnosis of smoke spillage at another site.
What should you record before the system is investigated?
- The affected appliance. Record which cooking equipment is producing the smoke or fumes.
- When the problem occurs. Note whether it happens all the time or only during busy periods or particular cooking processes.
- Where the smoke escapes. Identify whether it spills from one side of the canopy or across the whole capture area.
- Recent kitchen changes. Include new equipment, moved appliances, a changed menu or increased production.
- Fan behaviour. Note whether the fan sounds, starts and responds as expected.
- Recent cleaning and maintenance. Find the latest extract cleaning, inspection or mechanical service records.
- Visual evidence. Photographs or video can be useful where they can be obtained safely without interfering with kitchen operations.
Which contractor route may be appropriate?
Contamination or overdue cleaning
Where evidence points to grease or filter loading affecting performance, a competent kitchen extract cleaning contractor may be required.
Fan or control problem
Where fan duty, controls, motor condition or other mechanical issues are suspected, use a competent ventilation or mechanical specialist.
Capture or replacement air problem
Where the issue concerns plume capture, extract volume, make-up air or the effect of kitchen layout, competent ventilation assessment may be needed.
Access problem
If ductwork, fan or other system sections cannot be reached for inspection or maintenance, the access issue may need to be resolved first.
Unclear previous evidence
If earlier cleaning or inspection records do not show what was checked, cleaned or excluded, organise the evidence before another instruction is issued.
Contractor selection
Once the workstream is understood, check that the contractor’s competence, insurance and technical capability match the actual requirement.
Related kitchen extract problem guidance
This page focuses on smoke spillage and poor canopy capture. The parent guide covers the wider range of extraction problems, while the fan page goes deeper into weak pull and fan performance.
Smoke and canopy capture: frequently asked questions
Why is smoke escaping from my commercial kitchen canopy?
Smoke spillage can happen when the canopy is not capturing the cooking plume effectively. Possible causes include insufficient extract volume, poor replacement air, blocked filters, contamination, airflow disturbance, changes to cooking equipment or a ventilation system that is no longer matched to the cooking load.
Does smoke escaping from the canopy always mean the ductwork needs cleaning?
No. Contamination can reduce efficiency and may form part of the problem, but smoke spillage can also involve airflow, fan performance, replacement air, canopy position, equipment changes or system design.
Can dirty filters cause smoke to spill into the kitchen?
Yes. Heavily loaded filters can restrict airflow into the extract system. HSE also warns that fat residues and blocked air inlets can reduce ventilation efficiency and increase fire risk.
Can poor replacement air stop a canopy capturing smoke properly?
Yes. The air extracted from the kitchen has to be replaced. HSE guidance says kitchen ventilation design should provide suitable make-up air and avoid air movement that interferes with canopy capture.
Can new cooking equipment cause smoke spillage?
Yes. New or more intensive cooking equipment can change the amount of heat and fumes that the ventilation system needs to capture. The system may need to be reviewed against the new cooking load.
What should I do if smoke spillage started suddenly?
Record when the problem started, any changes made beforehand, the fan behaviour and any recent cleaning or maintenance work. A sudden change can help a competent contractor narrow the investigation.
What information should I send when asking for help with smoke spillage?
Send the site location, affected cooking equipment, when the problem occurs, photographs or video where safe to obtain, the latest cleaning or ventilation report, any recent kitchen changes and any known access or fan issues.
Is smoke escaping from the commercial kitchen canopy?
Send the site details, affected equipment, symptoms and recent maintenance information. EC can help organise the requirement so cleaning, airflow, replacement air, fan condition and access are considered separately before the appropriate independent specialist is approached.
Responsibility statement:
EC Cleaners Network is operated by Search and Submit Ltd. Search and Submit Ltd does not inspect, clean, test, survey, design, remediate, certify or technically approve kitchen extraction or ventilation systems. Independent appointed contractors and competent professionals remain responsible for technical assessment, safe working, quotations, physical delivery, reporting, certification and professional conclusions within their appointed scope.
TR19® Grease and TR19® Air are BESA specifications. References are descriptive and no BESA endorsement of or affiliation with EC Cleaners Network is claimed.