Why does my radiator tick and creak when the heating comes on?
Ticking, creaking and popping as a system heats is nearly always thermal expansion finding something to rub against. Where it comes from, and the small changes that quieten it.
- Difficulty
- beginner
- Time
- 20 min
- Read
- 4 min
Short answer
Metal expands as it heats and something is stopping it moving freely — a pipe gripped in a tight hole through a joist or floorboard, a radiator bracket, or a pipe clip. The noise is the moment it releases. It is not a fault, and easing the pinch point or padding it is the fix.
Almost every house does this, and it is one of the noises people worry about needlessly. Steel and copper both grow measurably when they go from room temperature to heating temperature, and a long pipe run under a floor grows by an amount you can actually see. If it can slide, it makes no noise. If it is trapped, it builds stress until it slips, and each slip is a tick.
Step by step
- Work out when it happens.During warm-up and again during cool-down, and not while the system is at a steady temperature, is the signature of thermal expansion. Noise at a constant temperature is something else — flow noise, air or a pump.
- Locate it before you do anything.Have someone else start the heating from cold and listen carefully. Radiator, valve, pipe under the floor, pipe where it passes through a wall, or the bracket. The fix depends entirely on where the pinch point is, and guessing wastes an afternoon.
- Check where pipes pass through joists and floorboards.The most common cause by far. A pipe running through a notch or a drilled joist, or up through a tight hole in a floorboard, cannot expand along its length and binds. Easing the hole slightly, or sleeving the pipe with a short length of pipe insulation or plastic conduit, cures it.
- Check the radiator brackets.A radiator resting hard against a bracket, or hung slightly out of level so it bears on one point, creaks as it expands. Lifting the radiator briefly and refitting it so it hangs freely, with a smear of grease or a piece of felt at the contact point, usually stops it.
- Check the pipe clips.Clips holding a pipe too tightly stop it sliding. Clips fixed hard into masonry with the pipe grabbed rather than supported are the usual offenders. Loosening one clip in a run is often the entire fix.
- Look at where pipes touch each other or the structure.Two pipes crossing and touching, or a pipe resting against a joist edge, produces a distinct sharper tick. A piece of foam or felt between them silences it permanently.
- Consider the flow temperature.A system running at a very high flow temperature expands more and makes more noise. Lowering the flow temperature — which is worth doing for efficiency anyway — reduces the total expansion and can quieten a borderline case.
- Distinguish it from noises that do matter.Ticking and creaking during temperature changes is benign. Banging or hammering when a valve closes is water hammer. A boiling or whooshing from the boiler is kettling. A gurgle or trickle is air. Those three all have causes worth addressing.
Tips
- Mark the floorboard above where you hear it while the noise is happening. Finding it again cold is surprisingly hard.
- Sleeving pipes where they pass through timber is standard practice on new work precisely because of this. Retrofitting it is a small job with a permanent result.
- Radiators fixed to plasterboard walls can transmit and amplify the noise through the board. Felt pads at the bracket contact points make a noticeable difference.
- If the noise is new and the system was recently drained and refilled, check for air first — a trickling or gurgling component may be mixed in with the ticking.
If it doesn't work
Sharp tick under the floor as the heating starts
Cause: A pipe binding in a joist notch or a drilled hole — Fix: Lift the board, ease the hole a little and sleeve the pipe with felt or foam. This is the single most common cure and it is permanent.
Creak from the radiator itself
Cause: The panel expanding against its brackets, or hung out of level — Fix: Lift and rehang so it sits freely on the brackets, with felt or grease at the contact points.
Tick from where a pipe enters a wall
Cause: The pipe is mortared or plastered solidly into the hole — Fix: Chase out a little around it and pack the gap with a flexible sealant rather than hard mortar, so the pipe can move.
Noise appeared after new flooring was laid
Cause: The new floor is bearing on pipes, or boards were screwed down tight against a pipe run — Fix: Very common after laminate or engineered flooring. Locate the contact point and relieve it — an extra millimetre of clearance is usually enough.
Loud bang rather than a tick
Cause: Water hammer from a fast-closing valve, not expansion — Fix: Different problem entirely. Look at pipe clipping, high mains pressure and shock arrestors.
Questions people ask
Is it damaging anything?
No. It is a nuisance rather than a fault. The stress relieving itself as a tick is doing no harm to the pipe, though a pipe binding very hard over many years can eventually wear a groove in a joist.
Why is it worse in one room?
Because that room happens to have the pinch point. It is not about the radiator or the room, it is about where the pipe run is trapped, which is often several metres away from where the noise seems loudest.
Will lowering the flow temperature stop it?
It reduces it, sometimes enough to stop it entirely, because less temperature change means less expansion. It is worth trying, since a lower flow temperature is good for a condensing boiler anyway.