Hot water too hot — scalding from taps

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May Need Pro💷 £20£20015–30 min
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Safety First
⚠️ Scalding water from taps is a serious safety hazard. Ideal UK hot tap temperature is 50°C at the outlet. At 60°C, scalding occurs within 3 seconds. Reduce the temperature setting immediately.

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Most likely cause & what to check

1

For a cylinder system: locate the cylinder thermostat on the side of the hot water cylinder (airing cupboard). It should be set to 60°C — high enough to prevent Legionella (L8 guidance) but no higher. If it has been turned up above 65–70°C, reduce it now.

2

For an unvented cylinder: find the thermostat dial (usually on the lower immersion heater boss or a separate electronic controller). Set to 60°C.

3

For a combi boiler: adjust the DHW (domestic hot water) temperature dial on the front of the boiler. Most combi boilers allow adjustment between 35°C and 65°C. Set to 50–60°C.

4

Consider fitting a thermostatic blending valve (TMV) at the cylinder or at the point of use (e.g. over a bath) — this blends cold water with hot to deliver a safe temperature (typically 41–46°C at the outlet). TMVs are required by Building Regulations in new builds and care settings.

5

If the temperature does not reduce after adjusting the thermostat, the thermostat has failed and is not cutting out the heating element or boiler. A plumber should replace it.

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🛠 Tools & materials you may need

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