Why Is Heating Making Noise? (7 Sounds & What They Mean)

Banging, gurgling, hissing, ticking — central heating systems make a variety of noises, and each one points to a different cause. Some are harmless, others need attention. Here's a guide to the most common heating noises and what to do about them.

1. Banging or Knocking

Cause: Usually "kettling" — a buildup of limescale or sludge on the heat exchanger causes water to boil and steam, creating a banging or rumbling sound similar to a kettle. More common in hard water areas. Can also be caused by pipes expanding and contracting as they heat up.

Fix: Kettling requires a heating engineer to descale or power flush the system. Pipe expansion noise can be reduced by ensuring pipes have room to move in their clips — loose clips or pipes running through tight holes in joists can bang as they expand.

2. Gurgling

Cause: Air trapped in the system moving through the pipes and radiators. Very common and usually harmless, but indicates the system needs bleeding.

Fix: Bleed all radiators to release trapped air. Use a radiator bleed key — the Mudder 11-Piece Utility Key Kit includes a 4-way bleed key. See our guide on how to bleed a radiator. If gurgling persists after bleeding, there may be a leak introducing new air into the system.

3. Ticking or Clicking

Cause: Pipes expanding and contracting as they heat up and cool down. This is completely normal and happens in most heating systems. More noticeable in older homes where pipes run under floorboards or through tight spaces.

Fix: Usually no action needed. If the ticking is very loud or bothersome, a heating engineer can add pipe insulation or adjust pipe clips to reduce movement.

4. Whistling or Hissing

Cause: Water being forced through a partially closed valve — usually a TRV or lockshield valve that's not fully open, or a valve that's failing. Can also be caused by high water pressure in the system.

Fix: Check all TRVs and lockshield valves — make sure none are partially closed. If a specific radiator is whistling, the TRV may need replacing. The Honeywell Home Thera-5 TRV is a reliable replacement for faulty valves. Check boiler pressure — if above 2.5 bar, it may need to be reduced.

5. Rumbling from the Boiler

Cause: Kettling (limescale on the heat exchanger), low water pressure, or a failing pump. A rumbling boiler is a sign that something needs attention.

Fix: Check boiler pressure (should be 1–2 bar). If pressure is correct and the rumbling persists, call a heating engineer. Kettling and pump issues require professional diagnosis.

6. Dripping or Trickling

Cause: Water leaking from a valve, pipe joint, or the boiler itself. Even a small drip can indicate a developing leak that will worsen over time.

Fix: Locate the source of the drip. A dripping bleed valve can often be tightened slightly. A leaking pipe joint or boiler component requires a plumber or heating engineer.

7. Vibrating or Humming

Cause: The circulation pump vibrating against its housing or mounting. Can also be caused by air in the pump.

Fix: Bleeding the system often resolves pump air issues. If the pump itself is vibrating excessively, it may be failing and need replacement — call a heating engineer.

Quick Reference

Gurgling and ticking are the most common heating noises and are usually harmless — bleeding the radiators fixes gurgling in most cases. Banging, rumbling, and dripping warrant more attention and may need a professional.