Kettling, whistling
Scale or sludge in the heat exchanger, not enough water flow.
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Boiler Making Noise: Whistling, Banging or Gurgling
A boiler is never totally silent, but a new noise often announces a fault. Whistling, banging, a thud on ignition or gurgling: each noise has its cause. Our heating engineers find it and fix it 7 days a week, before it turns into a breakdown.
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Noise identifiedCause found on site
Gas and oilAll brands
Price given firstBefore any repair
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Whistling and kettling
A kettle-like noise, whistling or small cracks while the boiler heats usually come from the heat exchanger. Scale and sludge build up inside, water flows poorly, overheats in places and forms steam bubbles that collapse noisily. Engineers call it kettling.
Too low a flow gives the same noise: pump set too slow, most radiator valves nearly closed, a clogged filter. The boiler overheats locally and sometimes ends up in fault.
The engineer measures flow and return temperatures, checks the pump and the state of the exchanger. Depending on the case, he cleans or descales the exchanger, adjusts the pump or recommends a power flush of the system. He then checks the combustion to rule out the burner.
A bang or thud on ignition
A bang when the burner starts is not normal. On an oil boiler it is often delayed ignition: badly set electrodes, a worn nozzle that atomises poorly, wrong air setting. Oil builds up for a split second, then ignites all at once.
On a gas boiler, the same noise can come from a dirty or misplaced electrode, or a gas valve that opens too abruptly. Over time, these small shocks damage the combustion chamber and the flue.
This noise calls for a prompt visit. The technician cleans and sets the electrodes, replaces the nozzle or faulty part, adjusts the burner and then runs a combustion analysis to check that ignition is smooth again and the flue gases are right.
Gurgling and noises in the radiators
Gurgling in the pipes and radiators almost always means air in the system. It gets in after draining, a leak or a refill, and it also stops radiators heating properly.
A high-pitched whistle near a radiator comes rather from a nearly closed valve with water rushing through. Ticking or knocking in the walls when the heating starts is caused by pipes expanding and rubbing in a tight passage.
The engineer bleeds the system, restores the right pressure, adjusts the pump speed and the valve openings. When air keeps coming back, he looks for the reason: a faulty automatic air vent, a small leak or an expansion vessel to replace.
A heat pump that has become noisy
If your heating comes from a heat pump, noises mostly come from the outdoor unit: a fan rubbing, a worn bearing, a compressor knocking at start-up, or vibration passed to the wall by tired mounts.
A short hiss during defrosting is normal, as is a little cloud of steam. A metallic noise, a rumble that grows week by week, or very frequent starts and stops need a check, because they wear the compressor.
The technician checks fixings, anti-vibration mounts, fan, refrigerant pressures and settings. A heat pump that is too powerful for the house starts and stops constantly: the right settings make it quieter and more efficient.
Which noise, which cause?
Describe the noise on the phone: it is often enough for the engineer to know what to bring.
Bang on ignition
Delayed ignition: electrodes, nozzle, air setting or gas valve.
Gurgling
Air in the system or the radiators.
Humming
Circulation pump set too high or worn bearing.
Repeated clicking
Failed ignition attempts: the boiler does not detect the flame.
Vibration
Dirty fan or loose boiler fixings.
How we deal with a noisy boiler
You describe the noise
When it happens, how long it lasts and whether the boiler shows a code.
Listening and testing
The engineer runs the boiler, locates the noise, measures and gives the price of the fix.
Quiet again
He repairs, adjusts, checks the combustion and hands you the job sheet.
What our customers say
Where do we work?
We work all over Belgium, in Brussels, Flanders and Wallonia. An unusual noise deserves a visit before winter: give us a call.
BrusselsWalloon BrabantFlemish BrabantHainautNamur provinceLiège provinceLuxembourg provinceAntwerpEast FlandersWest FlandersLimburg
The brands we work with
Our technicians work on all brands: they install, service and repair appliances from the major manufacturers. For a new installation, we recommend the model that suits your home and budget.
We buy our equipment from all the major Belgian wholesalers and suppliers, including Facq, Van Marcke and Desco: genuine parts, quickly available.
Frequently asked questions
Is a noisy boiler dangerous?
Not always, but a bang on ignition or an overheating noise should not be ignored. Switch the boiler off if the noise is violent and call us on 0477 03 88 98.
Why does my boiler sound like a kettle?
The heat exchanger is scaled or dirty, or the water circulates too slowly. Descaling, a power flush or a pump adjustment usually solve it.
The radiators gurgle. What should I do?
Bleed them with the boiler off, then bring the pressure back to about 1.5 bar. If the gurgling comes back quickly, air is getting in somewhere: have the system checked.
Does the yearly service reduce noise?
Yes. Cleaning the burner and exchanger and setting the combustion prevent most ignition and overheating noises.
Do you repair noisy heat pumps?
Yes, our technicians also repair heat pumps: fan, compressor, anti-vibration mounts.
How much does it cost?
It depends on the cause. The engineer gives you the price once he has found where the noise comes from, before repairing.
A noise that worries you?
Call us, book a slot online or request a quote.