Boiler Noise FAQs
What do different boiler noises mean? Banging, gurgling, whistling, and kettling explained.
5 questions answered by our Gas Safe engineers
Why is my boiler making a banging noise?
Banging (or 'kettling') is usually caused by limescale or sludge build-up on the heat exchanger. Hot water trapped under the deposit boils and rumbles. A power flush or descaling treatment can resolve this.
Why is my boiler making a gurgling noise?
Gurgling often indicates air in the system. Bleeding your radiators should resolve it. If it persists, there may be a partial blockage or a leak allowing air in.
Why does my boiler whistle?
Whistling ('kettling') has the same cause as banging — scale or sludge build-up. It can also indicate low water pressure.
Is it normal for a boiler to make clicking noises?
Clicking during ignition is normal — the boiler is lighting. Repeated clicking without the boiler firing indicates an ignition fault. Call an engineer.
My boiler is making a loud humming noise — is this serious?
A faint hum is normal. Loud humming can indicate the pump is running too fast or is faulty, or there's an issue with the fan. Have an engineer investigate.
Still have a question?
Our Gas Safe engineers are happy to answer any boiler questions. Call or message us.
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