BoilerTroubleshooting2026-02-26
Hot Water Too Hot from Your Combi
Scalding hot water usually means a thermostat set too high or a faulty temperature sensor.
If your combi's hot water is uncomfortably hot, it's usually an easy adjustment — or a sensor fault.
Common causes
The hot-water temperature setting may simply be too high; a faulty flow sensor or thermistor can also cause inconsistent, overly hot water.
What to do
Lower the hot-water setting on the boiler; if it stays too hot or fluctuates, the sensor needs checking. Mixing valves add scald protection.
Key takeaways
- Lower the hot-water setting first
- Around 50°C is comfortable and safe
- Fluctuations suggest a sensor fault
- Mixing valves prevent scalds
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