Radiators Ticking, Creaking Or Cracking When Heating Up

What's happening?

Copper pipe and steel radiators grow longer as they heat, and a short run of pipe can lengthen by a few millimetres. Where it passes through a joist, rests against a floorboard or sits in a tight clip, it sticks, then jumps, and you hear a tick, creak or crack. The noise comes at the start of a heating cycle as everything warms, and again as it cools. A radiator rattling on its brackets, or a thermostatic valve ticking as it adjusts, gives a similar sound. The key difference from the problem to worry about is the sound. A tick or creak as the heating comes on and off is expansion. A loud bang or a rumble that continues while the boiler fires is a different fault, and a gurgle is air.

What usually causes it?

• Pipes expanding and catching on joists, floorboards or tight clips
• A radiator moving slightly on its wall brackets as it heats
• A thermostatic valve adjusting, producing a tick as the head moves
• Plastic pipe clips that have hardened or no longer grip
• Water at too high a flow temperature, increasing expansion
• Scale or sludge in the radiator making cracking sounds as it heats

Is it dangerous?

No. A tick or creak with no other symptom is expansion, not a risk.

Can I fix it myself?

Note when it happens and whether it comes from a radiator or the pipe. Check the radiator is sitting properly on its brackets and nothing is rubbing. If you can reach the pipe, a strip of felt or foam pipe lagging where it passes a joist often stops it. Lowering the boiler flow temperature a little reduces how fast things expand. Do not cut into the floor.

When should you call a heating engineer?

Call a heating engineer if the noise is a loud bang, if it is a continuous rumble or kettling from the boiler, if the radiator is cold in places, or if it is getting worse. Ask them to look at the pipe runs if the noise is in a floor and you want it dealt with.

What will the heating engineer actually do?

• Trace the noise to a radiator, valve, pipe run or the boiler
• Re-clip, sleeve or pad pipes where they pass joists and boards
• Check and reseat radiators and brackets
• Check the flow temperature and balance of the system
• Flush the radiator or system if scale is cracking as it heats

Who fixes this

• Heating not working

Questions people ask

Sources & References

1. Vaillant: why is my boiler making a noise?
2. Vaillant: heating controls
3. Vaillant: most common boiler problems