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What are the signs of a blocked extractor fan
Written By Ruth MacEachern01 January 2025
What are the signs of a blocked extractor fan
Like all household appliances, extractor fans need regular maintenance and cleaning to ensure that they continue to work effectively and remain as efficient as possible. Over time, extractor fans can suffer from a build up of material on the fan blades and filters that stop them working as well as they could, and ultimately mean that they are unable to shift as much moisture from the room where they’re located.
What causes extractor fans to become blocked?
Your extractor fan is one of the hardest working appliances in your kitchen or bathroom. The fan works by drawing air out of the room, and this air carries with it moisture, dust, and, in the case of a kitchen extractor, grease and smoke from cooking.
In your kitchen, sticky grease and smoke can adhere to the fan blades and the filter, and this causes dirt and dust to become trapped. As this builds up in layers, eventually it will get to the point where the fan is having to work much harder to move air through because there is limited space, and the fan blades are much heavier.
A similar process happens in your bathroom, although it is moisture that traps a layer of dust, which takes a lot longer to get to a point where the fan stops working properly.
How can you tell if an extractor fan is blocked?
There are a number of signs to look – or rather listen – out for that can indicate your fan is becoming blocked.
Often the first signal that a fan is becoming clogged is that it starts to make a lot more noise when it is running. As the motor starts to work harder it will make a lot more noise when running. Aside from using more energy to move air properly, the lifespan of the fan will also be affected because the components are under more stress.
Another signal that your extractor fan is becoming blocked is that it will be much less efficient. It will take longer to reduce the amount of moisture in the air, and cooking smells may start to permeate through your home more than normal. If you hold a piece of paper in front of the intake and it doesn’t move much, then the fan is not working properly.
Another signal that grime is starting to build up inside your extractor fan is that you will also see more dirt on the intake. If there is a big build up of grease or dust on the outside of the fan, it’s highly likely that there is more inside.
What can you do about a blocked extractor fan?
Ensuring that your extractor fans are working correctly is important. If they are not removing moisture from the air properly, then condensation can start to build up in your home which can lead to damp patches and mould growth. A build up of grease on a kitchen fan can also be a major fire risk.
Most extractor fans are designed to be easy to clean. The exterior can be removed to allow you to wipe the inside down – make sure that it is properly switched off before you do anything inside.
Fan blades are usually easy to clean, but the filter may need to be replaced.
If the build up of grease and dirt in your fan has been going on for a long term, it’s possible that the components have started to wear out. If cleaning the interior of the fan doesn’t help reduce the noise, or improve air flow, it might be time to consider a replacement.
Modern extractor fans are designed to be much more efficient than in the past, and many, including the EnviroVent Cyclone 7 are Filterless, which means that they are much easier to maintain.
Find out more
If you have noticed that your extractor fans are working less efficiently or making noise, or you are seeing an increase in condensation throughout your home, we can help.
Our local ventilation specialists cover the whole of the country and can carry out a free home survey at your property that identify the causes of condensation in your home. They can provide you with advice about the best way of tackling poor indoor air quality and help you choose the right products to improve air flow and avoid problems in future.
Simply enter your postcode below to find your local specialist.
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Find out more
Avoid condensation damp from becoming a problem in your home. Contact us today to book your free home survey. Our local ventilation specialists can visit your home to identify the causes of condensation and provide advice about the best ways to deal with it. Simply fill in your postcode to find a local expert who can help you.
Meet The Author

Ruth MacEachern
Product Manager
Ruth is recognised for her deep technical knowledge and regulatory insight.
With over 10 years’ experience in the building industry - across sales, planning, supervision and product management - Ruth combines deep regulatory expertise with real-world application. She holds a four-year degree in Building Control, graduating with the highest marks in her class and winning an award for her dissertation.
Ruth has worked closely with Building Control Officers on complex, high-risk projects, including post-Grenfell work, helping interpret regulations and guide compliant outcomes. Today, she plays a central role in Research and Development, shaping products, technical guidance and education across the industry through technical writing, articles for our blog, and webinars.
Passionate about raising standards, Ruth is driven by one goal: Making ventilation clearly understood, properly specified, and taken seriously.
