Saunier Duval
Overheating / poor temperature regulation
Water heater produces very hot water, risk of scalding, temperature difficult to control
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Faulty DHW NTC sensor, Sticking gas valve not modulating down, Scaled heat exchanger causing localized overheating, Flow rate too low
How to Fix / Troubleshooting
Safety first: Warn occupants about scalding risk. Turn off power and gas before internal work.
Steps:
- Increase flow: Open the hot tap fully and avoid mixing with cold at the tap while testing.
- Check DHW NTC: Inspect and, if necessary, replace the Saunier Duval DHW outlet NTC sensor.
- Descale: Have the primary heat exchanger descaled to improve heat transfer and reduce hotspots.
- Gas valve check: A technician should verify that the gas valve modulates correctly at low demand.
Warning: Persistent overheating requires professional diagnosis. Do not rely on mixing valves alone to control temperature.
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Repair Difficulty
Hard
4/5
Required Part
DHW NTC Sensor
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