Burst Radiator Pipe: What to Do Right Now

A burst radiator pipe empties the heating system onto your floor, and heating water is dirty, warm and often under pressure. The first five minutes decide how much damage it does.

Short answer: Turn the heating off at the controller. Close both valves on that radiator: the wheel-head valve turns by hand, and the lockshield on the other end turns with a spanner or pliers. Catch and soak up the water. If water reaches sockets or light fittings, switch the electricity off at the consumer unit, but only if you can do it safely. Then call for a repair.

Stopping the water, step by step

1. Heating off. Switch off at the room thermostat or programmer so the pump stops pushing water round.
2. Isolate the radiator. Close the valve at each end of the radiator. One has a handle or a thermostatic head (turn it to zero, then fully clockwise); the other is a lockshield under a plastic cap, which needs a spanner. Count the turns to close it so it can be set back the same later.
3. If the leak is on the pipe below the valves, closing them will not help. On a sealed system the pressure gauge will drop and the leak slows as it does. On an older system with a small tank in the loft, close the valve on the pipe that feeds that tank so it stops refilling.
4. Protect the room. Towels, a bowl or a baking tray under the leak, and move rugs and furniture out of the way.
5. Electrics. If water is near sockets or coming through a light fitting below, switch off at the consumer unit, but only if it is safe to reach it, as Electrical Safety First advises.

Why radiators and their pipes fail

Corrosion from inside. Air and water together rust the steel. Pinhole leaks usually appear along the bottom seam, and a rusted panel can split along a line.

Valve and joint failures. Compression nuts loosen, olives weep, and old valves crack at the body. A leak at a valve often starts as a drip that grows.

Accidental damage. A nail or screw through a floorboard into a pipe below, often after carpet fitting, or a radiator knocked off its brackets.

Freezing. A radiator or pipe in an unheated room, garage or loft can freeze and split in a hard frost.

What the repair involves

A split pipe is cut out and replaced with a new section, and a failed valve is changed after draining down that part of the system. A radiator that has rusted through is replaced rather than patched, because the rest of the panel is usually thin too. Afterwards the system is refilled, bled, pressurised and checked, and inhibitor is topped up so the new metal is protected. Repairs to the boiler itself are a heating engineer’s job; we do no gas work, but we do the radiators, valves and pipework.

If the water is still coming out, use our emergency burst pipe repair or leaking radiator service. For a slow drip rather than a burst, our guide to a leaking radiator helps you find the source first.