Home › Heating problems › The boiler is noisy
Heating engineer · Brussels and Wallonia
The boiler is noisy: whistling, banging, kettling
A boiler always makes some noise: fan, pump, ignition. A new noise, or one that's getting louder, almost always means something. When you hear it helps find the cause.
The most common causes
Gurgling
Air in the system: bleeding the radiators often solves it.
Kettling, rumbling
Limescale or sludge in the heat exchanger: water overheats in places. Common in hard-water areas.
Whistling
Water circulates badly: pressure too low, radiator valves closed, or a struggling pump.
Small ticks as it heats up
Pipes expand as they warm: often normal.
A loud bang on ignition
Ignition isn't happening properly. That's not normal: have it checked quickly.
What you can check yourself
- Note when you hear it: on start-up, all the time, or only when you run hot water.
- Check the pressure: between 1 and 2 bar with the boiler cold.
- Gurgling: bleed the radiators (guide below).
- Open any closed radiator valves.
Don't
- Opening the casing to find where the noise comes from.
- Ignoring a loud bang on ignition.
- Smell gas as well? Follow our « Smell of gas » page.
Call us if…
- A loud bang or small explosion on ignition.
- A kettling or rumbling noise.
- The noise continues after bleeding and with the right pressure.
- The noise gets worse day by day.
What does a repair cost?
Call-out and diagnosis: €125 excl. VAT. The repair is extra, and you get its price before we start. We usually come within 24 hours (working days) and let you know 1 hour before we arrive.
This advice applies to most boilers. Every appliance has its quirks: if in doubt, your own manual applies, and we're happy to answer on the phone.
Frequently asked questions
My boiler makes a noise when I run hot water: why?
On a boiler that heats water on demand, it's often limescale in the hot water heat exchanger. It can be cleaned or replaced: call us before your hot water weakens.
Is a noisy boiler dangerous?
Most noises aren't dangerous, but they signal a coming fault. Switch the boiler off and call us if there's a loud bang on ignition or a smell of gas.
Find out more
A breakdown, a question? Get in touch.
Call us or message us on WhatsApp. Or leave your number, with a photo of the boiler if you like: we'll call you back.
