Why is my boiler noisy?
Most boiler noises have an everyday cause, like air in the system or low pressure. A few mean it should be looked at straight away. Here's what each one usually means.
- 6common noises and what they mean
- 1 to 1.5bar: check the pressure first
- 0800 111 999if you smell gas
6common noises
Boilers make some noise. A click when it fires, a soft hum from the pump and the odd tick as pipes warm up are all normal.
What matters is a new noise, or one that's getting louder. Here's how to tell the everyday ones from the ones to act on.
Six common boiler noises
| Noise | Sounds like | Usual cause | What to do |
|---|---|---|---|
| Kettling | A kettle coming to the boil | Sludge or scale on the heat exchanger, or poor water flow | Book an engineer |
| Gurgling | Water bubbling through the pipes | Air in the system, or a frozen condensate pipe in cold weather | Bleed the radiators, check the pipe outside |
| Whistling | A high pitched whistle | Low pressure, poor flow or a blockage | Check the pressure first |
| Humming | A steady low drone | Pump speed or vibration, or loose pipe clips | Book an engineer if it's new |
| Clicking | A ticking clock | Normal when the boiler fires. Constant clicking with no flame is an ignition fault | Book an engineer if it won't light |
| Banging | A thump or a bang | Water hammer in the pipes, or the boiler lighting late | A bang from the boiler: call us straight away |
Most of Fife's water is soft, so limescale in the boiler is less common here than in hard water areas. Kettling here is more often sludge or a flow problem.
What you can check safely
Before you book anyone.
- Gurgling: bleed the radiators to let trapped air out
- Check the pressure: it should read 1.0 to 1.5 bar with the heating cold
- In freezing weather: check the white plastic condensate pipe outside isn't frozen
- A fault light: reset the boiler once, as the manual says
Never take the boiler casing off. Only a Gas Safe registered engineer should work inside the boiler.
Safe checks
Call straight away if
These need an engineer, not a wait and see.
- You smell gas: open the windows, don't touch electrical switches, turn the gas off at the meter if it's safe to reach and call the gas emergency line on 0800 111 999
- Your carbon monoxide alarm sounds: open windows, get everyone outside and call 0800 111 999
- A loud bang when the boiler lights
- Soot or brown staining on or around the boiler or flue
- The boiler keeps locking out after a reset
Our engineers are Gas Safe registered. A repair visit is £120 inc VAT, and any parts are priced before we fit them.
Gas Safe registered
Which one sounds like you?
- GurglingBleed the radiators
Let the air out.
- Kettling or whistlingBook an engineer
Often sludge or flow.
- Gurgling on a frosty morningThaw the pipe
The pipe outside has frozen.
- A bang from the boilerCall us now
Don't keep resetting it.
Common questions
Is a noisy boiler dangerous?
Usually not. Most noises come from air, pressure or sludge. A bang when it lights, soot, or a gas smell are the exceptions, and need an engineer straight away.
Why does my boiler gurgle?
Usually air in the system, which bleeding the radiators fixes. In freezing weather it can be a frozen condensate pipe outside.
What is kettling?
A rumbling like a kettle, caused by water overheating in parts of the heat exchanger, usually because sludge or scale is restricting the flow.
Will a service stop the noise?
Sometimes. A service clears and checks the boiler, but a worn pump or a sludged system needs a repair or a clean.
Why does my boiler click?
A click or two when it fires is normal. Constant clicking without lighting is an ignition fault.
How much does it cost to have a noise checked?
A repair visit is £120 inc VAT. If we can fix it on the visit, that's all you pay. Parts are priced before we fit them.
Related pages
Not sure what you need? Give us a shout.
Book online in a couple of minutes or give the office a call, Mon to Fri, 9am to 5pm. We'll tell you what we think, and if the answer is to leave things as they are, we'll say that too.
Worcester Bosch Accredited Installer
Guarantees of up to 12 years on the boilers we fit. Gas Safe registered. Fife Trusted Trader. 400+ customer reviews.