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Kitchen extraction cleaning - smells
You wipe the canopy and it's clean - yet a stale, greasy smell hangs around whenever the extraction runs. The reason is usually that the smell isn't coming from the visible canopy at all, but from the hidden ductwork and fan, where grease has built up and is decomposing. Here is why a clean canopy can still smell, and what to do. This is general guidance.
The short answer
It's a common and frustrating puzzle: the canopy is clean, you keep it wiped - yet there's a persistent stale, greasy smell, especially when the extraction is running. The explanation is straightforward once you know where to look. Here's why. This is general guidance. The smell isn't from the canopy. The key realisation is that the smell isn't coming from the clean canopy at all. If the canopy is genuinely clean but the smell persists, the source must be elsewhere - and in an extraction system, 'elsewhere' means the hidden parts: the ductwork and the fan. So a clean canopy but a persistent smell points to the hidden system, not the surface you can see. Where the smell comes from. The smell comes from grease decomposing in the hidden ductwork and fan. As grease builds up in the ductwork and on the fan (the internal parts, out of sight), it decomposes over time - and decomposing grease gives off a stale, unpleasant, greasy smell. When the extraction runs, the airflow through the system carries that smell (as covered in the smell-that-tells-you-grease-has-reached-the-duct and smell-of-stale-grease pages). So the smell is the smell of stale, decomposing grease in the hidden system - carried out by the airflow. Why the clean canopy doesn't help. Why doesn't keeping the canopy clean solve it? Because wiping the canopy cleans only the visible surface - it doesn't reach or remove the grease in the hidden ductwork and fan. So the hidden grease (and its smell) stays there, however clean the canopy looks. The canopy cleaning and the smell are unrelated: the surface you clean is not the source of the smell (the hidden grease is). This is the same principle as a clean-looking canopy hiding a grease-laden system - the smell is just another sign that the hidden system is grease-laden. So the smell is a symptom of hidden grease that canopy cleaning can't touch. The fix: clean the hidden system. So the fix isn't more canopy cleaning (which won't reach the smell's source), but a proper extraction clean that removes the grease from the hidden ductwork and fan - clearing the decomposing grease that's causing the smell. Once the hidden grease is removed (by a full clean to the TR19 Grease standard, reaching the ductwork and fan), the source of the smell is gone, and the smell clears. So a clean canopy that still smells is telling you the hidden system needs cleaning. What if it still smells after that. A stale grease smell with a clean canopy usually points to the hidden ductwork - but occasionally a persistent kitchen smell has other sources (notably the drains - a separate, drainage issue). So if a proper extraction clean doesn't clear the smell, consider other causes (like the drains). But the usual cause of a stale grease smell with a clean canopy is the hidden extraction grease. The takeaway. So a clean canopy that still smells means the smell is coming from the hidden ductwork and fan, where grease has built up and is decomposing - not from the clean surface you see. Wiping the canopy doesn't reach it; only a proper extraction clean of the hidden system clears the smell. So clean the hidden system to clear the smell. This is general guidance.
Key points
The smell isn't the canopy
The key realisation is that if the canopy is clean but the smell persists, the smell isn't coming from the canopy at all. A genuinely clean surface doesn't produce a stale grease smell - so if the smell is there despite a clean canopy, its source must be elsewhere. And in an extraction system, 'elsewhere' means the hidden parts: the ductwork and the fan, behind and above the visible canopy.
So a clean canopy but a persistent smell points to the hidden system, not the surface you can see. This is the crucial reframing: you've been keeping the visible part clean, but the smell is telling you the problem is in the part you can't see. The smell is, in effect, a signal from the hidden system - a way it makes its grease-laden state known even though you can't see inside it. So the smell isn't the canopy - a clean surface, a hidden source - is the starting point: don't keep focusing on the clean canopy; look to the hidden ductwork and fan for the source of the smell. The following sections cover where the smell comes from and how to clear it. So the persistent smell points to the hidden system, not the clean canopy. This is general guidance.
Where the smell comes from
The smell comes from grease decomposing in the hidden ductwork and fan. As grease builds up in the ductwork and on the fan (the internal parts, out of sight), it decomposes over time - and decomposing grease gives off a stale, unpleasant, greasy smell. So the hidden grease isn't just a fire risk and a drag on airflow; it also smells as it ages and breaks down.
When the extraction runs, the airflow through the system carries that smell out - which is why the smell is often noticeable especially when the extraction is on (the airflow drawing the stale-grease smell through the system and into the kitchen or discharge). So the smell is the smell of stale, decomposing grease in the hidden system, carried by the airflow (as covered in the smell-that-tells-you-grease-has-reached-the-duct and the-smell-of-stale-grease pages). This is a recognised sign that grease has built up in the ductwork - the smell is one of the ways a grease-laden duct reveals itself. So where the smell comes from - grease decomposing in the duct and fan - identifies the source: the hidden grease, ageing and smelling, carried out by the airflow. Knowing the source points to the fix (cleaning that hidden grease). So the smell is decomposing hidden grease, carried by the airflow. This is general guidance.
Why cleaning the canopy doesn't help
Why doesn't keeping the canopy clean solve the smell? Because wiping the canopy cleans only the visible surface - it doesn't reach or remove the grease in the hidden ductwork and fan. So the hidden grease (and its smell) stays there, however clean the canopy looks. The canopy cleaning addresses the surface; the smell's source is the hidden grease, which the surface cleaning can't touch.
So the clean canopy and the persistent smell coexist because they're unrelated: the surface you clean isn't the source of the smell (the hidden grease is). This is the same principle as a clean-looking canopy hiding a grease-laden system (covered in the why-your-canopy-looks-clean-but-isnt page) - the smell is just another sign that the hidden system is grease-laden, one that the canopy cleaning can't address. So no amount of canopy wiping will clear the smell, because it doesn't reach the grease causing it. This is why the smell persists despite your efforts on the canopy - you've been cleaning the wrong part (relative to the smell). So why cleaning the canopy doesn't help - it doesn't reach the hidden grease - explains the puzzle: the smell comes from grease the canopy cleaning never touches. The fix is to clean that hidden grease (covered next). So canopy cleaning can't clear a smell from the hidden system. This is general guidance.
The fix
So the fix isn't more canopy cleaning (which won't reach the smell's source), but a proper extraction clean that removes the grease from the hidden ductwork and fan - clearing the decomposing grease that's causing the smell. A full clean to the TR19 Grease standard reaches the whole system (the ductwork and fan, not just the canopy), removing the built-up grease - so the source of the smell is taken away.
Once the hidden grease is removed, the stale-grease smell has nothing to come from, so it clears. So the solution to a clean canopy that still smells is to have the hidden system properly cleaned - the ductwork and fan - which addresses the actual source. This also, of course, deals with the fire risk and airflow problems the hidden grease was causing (the smell being one symptom of a grease-laden hidden system among several). So the fix - clean the hidden ductwork and fan - is a proper extraction clean, not more surface wiping: remove the hidden grease, and the smell goes with it. This is why a clean canopy that still smells is really a prompt to get the hidden system cleaned. So clear the smell by cleaning the hidden grease. This is general guidance.
If it still smells
A stale grease smell with a clean canopy usually points to the hidden ductwork - but occasionally a persistent kitchen smell has other sources, notably the drains (a separate, drainage issue, from grease and food building up in the drains and grease trap). So if a proper extraction clean doesn't clear the smell, consider other causes.
The most common alternative source is the drains: a smelly-drain problem can produce a stale, greasy or unpleasant smell that might be mistaken for (or coexist with) an extraction smell (as covered in the why-do-my-kitchen-drains-smell page). So if you've had the hidden extraction properly cleaned and a smell persists, look at the drainage (the drains, gullies, grease trap) as a possible source, and address that. But this is the exception: the usual cause of a stale grease smell with a clean canopy is the hidden extraction grease, and cleaning the hidden system usually clears it. So if it still smells - consider other sources, like the drains - is the follow-up: a proper extraction clean is the first and usual fix, and if the smell survives it, investigate the drains or other sources. So clean the hidden system first; if the smell persists, check the drains. So the duct is the usual cause; the drains a possible other. This is general guidance.
Questions
Because the smell comes from the hidden ductwork and fan, not the canopy - grease built up there decomposes and gives off a stale smell, carried out when the extraction runs; wiping the canopy doesn't reach it. If your canopy is clean but there's a persistent stale, greasy smell, the smell isn't coming from the canopy - it's coming from the hidden parts of the system: the ductwork and fan. Grease that has built up there (out of sight) decomposes over time, giving off a stale, unpleasant smell, which the airflow carries when the extraction runs. Wiping the canopy cleans only the visible surface - it doesn't reach or remove the hidden grease - so that grease and its smell stay there however clean the canopy looks. So the clean canopy and the persistent smell coexist because they're different parts: the surface you clean, and the hidden grease that smells. The fix is a proper extraction clean of the hidden ductwork and fan, removing the decomposing grease at the source. So because the smell is from the hidden grease, which canopy cleaning can't reach. So the hidden ductwork is grease-laden. This is general guidance.
From grease decomposing in the hidden ductwork and on the fan - the internal parts you can't see; as the built-up grease ages it gives off a stale smell, which the airflow carries out when the extraction runs. The smell is coming from grease decomposing in the hidden ductwork and fan - the internal parts of the extraction, out of sight. As grease builds up there over time, it decomposes, and decomposing grease gives off a stale, unpleasant, greasy smell. When the extraction runs, the airflow through the system carries that smell out (which is why it's often most noticeable when the extraction is on). So the source is the stale, ageing grease in the hidden system - not the clean canopy you see. This is a recognised sign that grease has built up in the ductwork: the smell is one of the ways a grease-laden hidden system reveals itself (alongside weak airflow, a louder fan, and so on). So the smell is coming from where you can't see - the ductwork and fan - which is why keeping the visible canopy clean doesn't clear it. The fix is cleaning that hidden grease. So from decomposing grease in the hidden ductwork and fan. So the hidden internal parts. This is general guidance.
Because wiping the canopy cleans only the visible surface - it doesn't reach the grease in the hidden ductwork and fan, which is where the smell comes from; so the hidden grease and its smell stay there however clean the canopy looks. Cleaning the canopy doesn't get rid of the smell because it doesn't reach the source. Wiping the canopy cleans only the visible surface - it can't reach or remove the grease in the hidden ductwork and fan, which is where the smell actually comes from (decomposing grease). So the hidden grease, and its smell, stay in place however clean the canopy looks. The canopy cleaning and the smell are unrelated: the surface you're cleaning isn't the source of the smell. This is the same reason a clean-looking canopy can hide a grease-laden system - the visible surface and the hidden grease are cleaned (or not) separately. So no amount of canopy wiping will clear a smell whose source is the hidden ductwork and fan. To clear the smell, you have to clean the part it comes from - the hidden system - with a proper extraction clean. So because it doesn't reach the hidden grease causing the smell. So the smell's source is hidden, beyond the wipe. This is general guidance.
Have the hidden ductwork and fan properly cleaned to TR19 Grease - removing the decomposing grease that's the source of the smell; once the hidden grease is gone, the smell clears, which canopy wiping alone can't achieve. To get rid of a stale grease smell with a clean canopy, have the hidden system properly cleaned. A full extraction clean to the TR19 Grease standard reaches the whole system - the ductwork and fan, not just the canopy - and removes the built-up grease that's decomposing and causing the smell. Once that hidden grease is removed, the source of the smell is gone, so the smell clears. So the fix is a proper extraction clean of the hidden ductwork and fan, not more canopy wiping (which won't reach the source). This also deals with the fire risk and airflow problems the hidden grease was causing - the smell being one symptom of a grease-laden hidden system. So arrange a proper extraction clean to remove the hidden grease and clear the smell. If a proper clean doesn't clear it, consider other sources like the drains. So have the hidden ductwork and fan cleaned. So clean the hidden grease at the source. This is general guidance.
Then consider other sources - most commonly the drains (a separate drainage issue from grease and food build-up); a stale grease smell usually clears with a proper duct clean, so a persisting smell points elsewhere. If a stale grease smell remains after a proper extraction clean of the hidden ductwork and fan, the source is probably something else - most commonly the drains. A smelly-drain problem (grease and food building up in the drains, gullies and grease trap, decomposing) can produce a stale, unpleasant smell that might be mistaken for or coexist with an extraction smell. So if you've had the hidden extraction properly cleaned and a smell persists, look at the drainage (the drains, gullies and grease trap) as a likely source, and address that with drainage maintenance (as covered in the why-do-my-kitchen-drains-smell page). Other possible sources exist too (a general odour issue in the building). But this is the exception: a stale grease smell with a clean canopy usually is the hidden extraction grease, and a proper duct clean usually clears it. So clean the ductwork first (the usual cause); if the smell survives, investigate the drains. So consider the drains or other sources. This is general guidance.
Yes - a stale grease smell (especially with a clean canopy, and when the extraction runs) is a recognised sign that grease has built up in the hidden ductwork and fan and needs cleaning; the smell is the hidden grease making itself known. Yes - a stale, greasy smell is a recognised sign that your extraction needs cleaning, especially when the canopy is clean and the smell comes with the extraction running. The smell is caused by grease decomposing in the hidden ductwork and fan - so its presence tells you grease has built up in those hidden parts (which you can't see) and is ageing and smelling. In other words, the smell is the hidden grease making itself known - a symptom of a grease-laden hidden system, alongside other signs like weak airflow, a louder fan, or a hotter kitchen. So take a persistent stale grease smell as a prompt to get the hidden system checked and cleaned (a proper extraction clean of the ductwork and fan). Don't just try to mask it or keep wiping the canopy - the smell is telling you the hidden system needs cleaning. So yes - it's a sign the hidden ductwork is grease-laden and due a clean. So yes; the hidden grease is signalling. This is general guidance.
A clean canopy that still smells means grease is decomposing in the hidden ductwork and fan; we clean the whole system to TR19 Grease, removing the hidden grease at the source of the smell - which the daily canopy wipe never reaches. Ask us to clean the hidden system and clear the smell. This is general guidance.
