Noisy Kitchen Exhaust Fan? Causes and When to Clean It

A noisy kitchen exhaust fan is usually the first sign that something has changed. The fan normally sits on the roof or in a ceiling void, so by the time smoke lingers in the kitchen the problem has often been building for a while. This guide explains the common causes of a noisy or vibrating exhaust fan, what your team can check safely, and what needs a professional.

Why is my kitchen exhaust fan noisy?

• Grease on the blades: grease collects unevenly, which unbalances the fan, causes vibration and a humming or thumping sound, and strains the motor
• Worn parts: bearings and, on belt-driven fans, belts wear with use and can squeal, rumble or rattle
• Loose fixings: a loose mounting, guard or duct connection can rattle, especially when the fan vibrates
• Damage or debris: a bent blade, or an object in the housing, can cause scraping or an uneven sound
• Restricted airflow: clogged filters or grease in the duct make the fan work harder, and too little replacement air can make air whistle at doors and windows

What can your team check safely?

Keep to what can be done from the kitchen, with the burners off and cooled:

1. Note what the sound is and when it started: a hum, a rattle, a squeal, or a steady thump that follows the fan's speed. A change is more useful to an engineer than a general complaint that the fan is loud.
2. Check that the filters are clean and sit tightly. Clogged filters make the fan work harder.
3. Look at the hood and the grease cups for dripping grease, which means grease is building up beyond the filters.
4. Ask building maintenance to look for grease streaks around the roof outlet, without opening the fan housing.
5. Watch whether smoke and heat clear more slowly than before.

Do not open the fan housing or touch the blades. The fan has to be isolated from power and locked off first, which is a job for trained technicians.

What needs a technician or an engineer?

Worn bearings, belts and motors, electrical faults and fan balancing are jobs for a ventilation or electrical engineer. HoodEx cleans exhaust fans, and repairs are for an engineer. If you already know there is a mechanical problem, cleaning the fan first gives the engineer a clean fan to inspect. Every job ends with a company-attested report that includes before and after photos and recommendations, which you can pass on.

When does cleaning the fan help?

If the cause is grease, cleaning helps. Grease on the blades unbalances the airflow and puts extra strain on the motor, and cleaning the blades and housing supports smoother, more balanced operation and more consistent extraction. It will not fix a worn bearing or a loose mounting, which is why we inspect first and recommend only what the system needs.

Our exhaust fan cleaning covers the blades, the housing and the motor compartment. It can be booked on its own or as part of the complete exhaust system cleaning.

Is the noise coming from somewhere else?

Sometimes the fan is only the loudest part of a wider problem. Grease in the exhaust duct narrows the path and slows the air, and a greasy hood and filters cut airflow before it reaches the duct. If smoke is also staying in the kitchen, read how to fix smoke in a restaurant kitchen, and if the kitchen smells of old oil, see why a kitchen smells of old cooking oil.

What if the fan stops?

If the exhaust fan stops, or the kitchen fills with smoke, stop cooking and call your engineer. Cooking without extraction fills the kitchen with smoke, heat and grease vapour.

How often should the exhaust fan be cleaned?

The fan is part of the full system, so it follows the same schedule as the duct. The NFPA 96 benchmark runs from monthly for solid-fuel cooking to yearly for low-volume cooking; see how often to clean a commercial kitchen exhaust. A fan that is noisy or vibrating now should not wait for the next date. For the checks your team can do each week, use our kitchen exhaust maintenance checklist.

Noisy exhaust fan in your restaurant or hotel kitchen? Contact HoodEx and we will arrange an inspection. We work day and night shifts, so a visit can be arranged outside your trading hours.

Frequently asked questions