The extract fan is the heart of a kitchen ventilation system. If it slows down, the whole kitchen feels it: heat, smoke and smells hang around, and staff start to complain. Fan problems usually come from one of two places. Either grease has built up on the fan, or something mechanical or electrical is wearing out. Sometimes it’s both. This guide explains the common symptoms and what usually causes them.
Noise and vibration
A fan that rattles, hums louder than usual or makes the ductwork shake is telling you something. The two usual causes are:
- Grease imbalance. Grease builds up unevenly on the impeller blades. Even a small amount of extra weight on one side makes the fan wobble at speed.
- Worn bearings. Bearings wear over time, and grease and heat can speed that up. Worn bearings tend to grind, squeal or rumble.
Grease imbalance often improves once the fan is cleaned. Bearing noise doesn’t, and the bearings or the fan may need replacing.
Slow or weak extraction
If the kitchen fills with smoke and steam, the fan may not be moving enough air. Common reasons include:
- clogged grease filters restricting airflow
- grease build-up in the duct narrowing the airway
- a greasy impeller that can’t move air as well
- a slipping or worn drive belt, on belt-driven fans
- a motor that’s failing or a speed control fault
Start with the simple things: clean filters and check the fan is set to the right speed. If that doesn’t help, the system needs an inspection.
Tripping and cutting out
A fan that trips the electrics or stops on its own is a warning sign. An overloaded motor, perhaps working harder because of grease or a failing bearing, can overheat and cut out. Moisture or grease getting into electrical parts can also cause trips. Electrical faults need a competent person, so don’t keep resetting a fan that keeps tripping.
Need it done? Duct Doctor cleans and tests kitchen extract and ventilation systems across London and the South East, with a certificate and photo report after every clean. Get a fixed quote.
Grease, heat and fire risk
The fan and its housing are part of the extract system that holds grease. Fans run warm, and a grease-coated fan in a duct full of grease adds to the fire risk. That’s why a TR19® Grease clean includes the fan and its housing, not just the canopy and duct. If your last certificate doesn’t mention the fan, ask why. See canopy-only versus full cleans.
Clean, repair or replace
- Clean if the fan is greasy but runs smoothly once the grease is off. Extract fan cleaning is part of a full system clean, or can be done on its own.
- Repair if a part such as a belt, bearing or capacitor is worn but the fan is otherwise sound.
- Replace if the motor has failed, the impeller is damaged, or repairs would cost more than a new fan.
Duct Doctor offers extract fan repair and replacement, and we’ll tell you which option makes sense after looking at the fan. If the fan fails during service, our 24/7 emergency callout is there to help.
Keeping the fan healthy
- Keep filters clean so less grease reaches the fan.
- Stick to the cleaning interval on your certificate.
- Report new noises early. Small problems are cheaper to fix than a seized fan.
- Make sure the fan can be reached safely for cleaning and servicing.
Quick answers
Why is my extract fan so loud?
Usually grease imbalance on the blades or worn bearings. A clean shows which.
Can a greasy fan catch fire?
Grease on the fan and in its housing is fuel, so it adds to the fire risk. It should be cleaned with the rest of the system.
Should I keep resetting a fan that trips?
No. Repeated tripping points to a fault that needs a competent person.
Related services
More advice
- Signs Your Kitchen Extract Needs Cleaning
- Canopy-Only Cleaning vs a Full TR19 Clean
- Grease Filter Cleaning: How Often and How
- Kitchen Extract Fires: How They Start and Spread
- All advice
This guide is general information. It isn’t legal or insurance advice: check your own policy wording and lease, and speak to a qualified adviser about your fire risk assessment.