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Extraction cleaning - roof fans
A roof extract fan that starts to struggle - moving less air, working harder, not clearing the kitchen as it should - is often telling you about grease. Grease fouling the fan and clogging the system it works against can make the fan struggle, so a struggling roof fan frequently points back to a grease problem. Understanding the connection helps you read the sign and act on it.
The short answer
A roof extract fan struggling to move air is often a grease problem. Grease can foul the fan itself - building up on the impeller, making it heavier and less efficient, so it moves less air. And grease clogging the system the fan works against - the grease-laden filters and ductwork restricting the airflow - makes the fan work harder for less result. So both the fan being fouled with grease and the system being clogged with grease can make the roof fan struggle. This means a struggling roof fan frequently points back to a grease problem - the fan fouled, the system clogged, or both. So when the roof fan starts to struggle, grease is a prime suspect, and the response is to have the fan and system cleaned to restore the airflow.
A struggling fan is telling you something
A roof extract fan - the fan mounted on the roof that drives the kitchen's extraction, pulling the air through the system and out - can start to struggle over time: moving less air than it should, working harder, not clearing the kitchen of heat and fumes as effectively as it used to. When a roof fan starts to struggle like this, it is telling you something is wrong with the system, and very often what it is telling you about is grease. Grease is frequently the cause behind a struggling extract fan, so a fan that is not performing as it should is often a sign of a grease problem.
Understanding this connection is useful, because it helps you read the sign of a struggling fan and respond to it correctly. Rather than seeing a struggling roof fan as just a fan problem - something wrong with the fan itself in isolation - it is often more accurate to see it as a grease problem showing up at the fan. The grease affects the fan and the system in ways that make the fan struggle, so the struggling fan points back to the grease. Knowing this means that when the roof fan starts to struggle, grease is a prime suspect to investigate - which often leads to the right response of cleaning the fan and system to restore the airflow.
Grease fouls the fan
One way grease makes a roof fan struggle is by fouling the fan itself. The fan works by its impeller - the bladed wheel that moves the air - spinning to drive the airflow. But the fan is moving grease-laden air, so grease deposits on the impeller and the fan over time, building up on the blades. A grease-fouled impeller is both heavier and less aerodynamically efficient than a clean one - the grease adds weight and disrupts the airflow over the blades - so it moves less air for the same effort. So grease building up on the fan directly reduces the fan's performance, making it move less air.
This is a direct grease effect on the fan: the grease coating the impeller degrades the fan's ability to move air, so a heavily grease-fouled fan struggles to produce the airflow it should. And because the roof fan is drawing grease-laden air through the whole system, it is exposed to grease continuously, so this fouling builds up if not addressed. So a roof fan that has accumulated grease on its impeller will struggle - moving less air because the grease has made the impeller heavier and less efficient. This is one half of the grease connection: the fan itself being fouled with grease and losing performance as a result. Cleaning the grease off the fan restores the impeller's efficiency and the fan's airflow.
Grease clogs the system
The other way grease makes the roof fan struggle is by clogging the system the fan works against. The fan does not move air in isolation - it draws air through the whole extraction system, the filters and ductwork, against the resistance they present. When those are clogged with grease - grease-laden filters and grease-lined ductwork restricting the airflow - the resistance the fan works against is greater, so the fan has to work harder to move air through the clogged system, and moves less air for its effort. So grease clogging the system makes the fan struggle, not by fouling the fan itself, but by increasing the resistance it has to overcome.
This is the system-side of the grease connection: even a clean fan struggles if the system it draws through is clogged with grease, because the grease build-up in the filters and ducts restricts the airflow and makes the fan work against greater resistance. So a roof fan struggling can be a sign that the wider system is grease-clogged, restricting the airflow the fan is trying to produce. Between the two effects - grease fouling the fan and grease clogging the system - grease can make the roof fan struggle from both directions. A struggling fan might have a grease-fouled impeller, a grease-clogged system, or both, all making it move less air. This is why grease is such a prime suspect when the roof fan struggles: it can cause the struggle in more than one way, both traceable to grease build-up.
Reading the sign and acting
Because grease is so often the cause, a struggling roof fan should prompt you to investigate grease and, typically, to have the fan and system cleaned. The right response to a roof fan that has started to struggle is to check whether grease is the cause - which it frequently is - and to address it by cleaning the grease off the fan and out of the system. Cleaning the grease-fouled impeller restores the fan's efficiency; cleaning the grease-clogged filters and ductwork reduces the resistance the fan works against. Together, cleaning the fan and system removes the grease that was making the fan struggle, restoring the airflow.
So the struggling roof fan is a useful sign, pointing to a grease problem that cleaning resolves. Reading it correctly - recognising that a struggling fan often means grease, fouling the fan or clogging the system or both - leads to the right response of cleaning rather than, say, assuming the fan is faulty and needs replacing when it is actually just grease-fouled. Of course, a fan can have genuine mechanical problems too, so grease is not the only possible cause; but it is a prime and common one, so it is the first thing to investigate when a roof fan struggles. And where grease is the cause, cleaning the fan and system restores the performance. So when the roof fan starts to struggle, think grease first: it is frequently the connection, and cleaning is frequently the answer. Understanding the grease connection helps you read the struggling fan as the sign it often is - a grease problem to be cleaned, not necessarily a fan to be replaced.
The takeaway
A roof extract fan that starts to struggle - moving less air, working harder, not clearing the kitchen as it should - is often telling you about grease. Grease can foul the fan itself, building up on the impeller and making it heavier and less efficient so it moves less air. And grease can clog the system the fan works against - grease-laden filters and grease-lined ductwork restricting the airflow - making the fan work harder for less result. So both a grease-fouled fan and a grease-clogged system can make the roof fan struggle.
This means a struggling roof fan frequently points back to a grease problem - the fan fouled, the system clogged, or both. So when the roof fan starts to struggle, grease is a prime suspect, and the response is to have the fan and system cleaned to restore the airflow - cleaning the grease off the impeller and out of the filters and ductwork. Reading the struggling fan as the grease sign it often is leads to the right response of cleaning, rather than assuming the fan is faulty. A fan can have genuine mechanical faults too, but grease is a common cause worth investigating first - so think grease when the roof fan struggles.
Questions
Because grease can affect the fan and system in two ways that make the fan struggle: fouling the fan's impeller so it moves less air, and clogging the filters and ductwork so the fan works against greater resistance. So a fan moving less air and working harder frequently points back to grease build-up.
The fan moves grease-laden air, so grease deposits on the impeller - the bladed wheel that moves the air - building up on the blades. A grease-fouled impeller is heavier and less aerodynamically efficient than a clean one, so it moves less air for the same effort, making the fan struggle.
The fan draws air through the whole system against the resistance the filters and ductwork present. When those are clogged with grease, the resistance is greater, so the fan has to work harder to move air through the clogged system and moves less air for its effort. Even a clean fan struggles if the system is grease-clogged.
Yes - grease can make the roof fan struggle from both directions at once: a grease-fouled impeller reducing the fan's own efficiency, and a grease-clogged system increasing the resistance it works against. A struggling fan might have either or both, all traceable to grease build-up, which is why grease is such a prime suspect.
Investigate grease, which is frequently the cause, and typically have the fan and system cleaned - cleaning the grease off the impeller to restore the fan's efficiency, and out of the filters and ductwork to reduce the resistance. Cleaning removes the grease that was making the fan struggle, restoring the airflow.
Yes - a fan can have genuine mechanical problems too, so grease is not the only possible cause. But it is a prime and common one, so it is the first thing to investigate when a roof fan struggles. Where grease is the cause, cleaning restores the performance rather than the fan needing replacement.
A struggling roof fan often means grease - fouling the fan or clogging the system. Our cleaning removes the grease from the fan, filters and ductwork, restoring the airflow the grease was choking.
