Why Is My Central Heating Making Noise?
Why Is My Central Heating Making Noise? Causes, Fixes & Professional Advice
Strange noises from your central heating can be worrying — especially if they appear suddenly or get louder over time. From banging and gurgling to whistling and tapping, each sound can point to a specific issue. Here’s what they mean, how to quiet them, and when to call in a heating engineer.
Quick insight: Most heating noises are caused by trapped air, limescale build-up, or changes in water pressure. Ignoring them can lead to leaks, inefficiency, or system damage over time.
Common Noises and What They Mean
1) Banging or “kettling” sounds
This usually happens when limescale builds up on the boiler’s heat exchanger. It restricts water flow, causing overheating and bubbling — similar to a kettle boiling.
- Fix: Power flush the system or fit a magnetic/limescale filter. In severe cases, the heat exchanger may need descaling or replacement.
- Prevention: Use scale inhibitors, especially in hard water areas.
2) Gurgling in radiators or pipes
Gurgling is a sign of trapped air in the system or low water pressure.
- Fix: Bleed your radiators starting from the top floor. Then check your boiler pressure — it should sit between 1 and 1.5 bar when cold.
- If it returns: You may have a small leak or a failing expansion vessel.
3) Whistling or high-pitched noises
Often caused by a partially closed valve or a faulty pump trying to move water through a restricted flow path.
- Fix: Check that radiator valves are fully open. If the noise comes from the boiler itself, a professional should inspect the pump or fan.
4) Tapping or clicking from pipes
These sounds usually come from pipes expanding and contracting as they heat up and cool down — especially where they run tight against floorboards or joists.
- Fix: Slightly loosen the pipe clips or add foam insulation where possible.
- Note: This is rarely dangerous, just annoying.
5) Loud humming or vibrating
A pump running too fast or a loose mounting bracket can create a noticeable hum.
- Fix: Reduce the pump speed or secure the bracket. If the vibration continues, a service engineer can balance the system.
Why You Shouldn’t Ignore Heating Noises
- They can indicate air or scale build-up that reduces system efficiency.
- Prolonged vibration may loosen fittings and joints, leading to leaks.
- Excessive heat stress from restricted flow can shorten boiler lifespan.
Tip: If you bleed radiators often or pressure keeps dropping, there may be an underlying leak or expansion vessel issue — get it checked by a Gas Safe engineer.
How to Keep Your System Quiet
- Book an annual boiler service to clean filters and check pump speed.
- Flush and treat the system every 5–7 years to remove sludge and limescale.
- Fit a magnetic filter and inhibitor fluid to protect components.
- Ensure radiators are balanced so water flows evenly throughout the system.
When to Call a Professional
If your system still makes noise after bleeding or pressure adjustment, it’s best to call a qualified engineer. Noises from inside the boiler, pump, or pipes can indicate internal blockages, worn bearings, or scaling that require specialist tools and expertise.
P A Henery Ltd are Gas Safe registered engineers providing prompt, clean, and reliable heating services across South London and Surrey.
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