Strange Noises coming from Your Boiler or Radiators?

What Is Water Hammer?

Water hammer is a banging or knocking sound from your pipes, radiators, or boiler, most noticeable when the heating system starts up or shuts down.

Common Causes of Water Hammer

• Sudden changes in water flow or pressure
• Loose or poorly supported pipework
• Airlocks in the heating system
• Worn or faulty valves
• Radiators turned off too quickly
• Expansion of pipes due to heat

Is Water Hammer Dangerous?

Water hammer is not usually an immediate safety risk, but over time it can damage pipe joints and fittings. This may lead to leaks or bursts, so it is always best to have the issue investigated.

Other Common Boiler and Heating Noises

Gurgling

• Often caused by trapped air in radiators or pipes
• May also indicate a build-up of sludge in the system
• Solution may involve bleeding radiators or carrying out a full system flush

Kettling (Boiling or Hissing Sounds)

• Usually due to limescale build-up in the heat exchanger
• Common in hard water areas
• Reduces boiler efficiency and can cause overheating
• May require chemical descaling or replacement of parts

Banging or Clanging

• May be caused by water hammer, loose pipework, or pressure changes
• Can also indicate a faulty pump or blocked valves

Humming or Vibrating

• Often linked to a worn or faulty pump
• May also result from loose boiler panels or components

Troubleshooting: Before contacting an engineer, you can try the following checks:

• Bleed radiators to remove trapped air
• Check the boiler pressure (should normally be between 1.0 and 1.5 bar when cold)
• Ensure radiator valves are fully open
• Look for visible leaks around pipes and joints
• Switch the boiler off, wait a short while, then restart it

Important: Never attempt to dismantle or repair internal boiler components yourself. Only a Gas Safe registered engineer should carry out this work.

When to Call a Heating Engineer

You should book professional help if you experience:

• Persistent banging or water hammer
• Gurgling that continues after bleeding radiators
• Boiler overheating, switching off, or showing error codes
• No heating or hot water
• Boiler pressure that drops and will not stabilise
• Visible leaks or dripping pipework

Professional Heating Repair Services

Our heating engineers provide:

• Central heating diagnostics and repairs
• Water hammer investigation and pipe stabilisation
• Boiler descaling and limescale removal
• Pump and valve replacement
• Power flushing to clear sludge and airlocks
• New boiler installations when required

Areas Covered

We provide heating and plumbing support across the whole of the UK, including:

• Major cities such as London, Manchester, Birmingham, Glasgow, Cardiff and Belfast
• Towns and villages nationwide
• Rural and coastal communities

Local engineers are available with same-day and next-day callouts in most areas.

Quick Guide: Boiler and Heating System Noises

Need Help With Noisy Pipes or a Noisy Boiler?

Do not wait until a small problem becomes a costly emergency. Our Gas Safe engineers are available to diagnose and repair noisy central heating systems anywhere in the UK.