Dimplex Overheating / Temperature Overshoot

Water is too hot, even at low temperature settings

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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

Stuck heating relay or triac, Faulty outlet temperature sensor reading low, Misadjusted or failed thermostatic mixing valve, Control PCB fault

How to Fix / Troubleshooting

Safety: Risk of scalding. Turn off the heater and allow it to cool before working on it.

  • Verify setpoint: Confirm the temperature setting on the Dimplex control panel is not set too high.
  • Check mixing valve: If a mixing valve is installed, adjust it to a lower temperature and test. Replace if it does not respond.
  • Inspect sensor: Ensure the outlet NTC sensor is correctly positioned and not loose. Replace if readings are clearly inaccurate.
  • Check for stuck relay: Listen for relays clicking off when demand stops. If elements remain energized, the control PCB relay/triac may be stuck and must be replaced.
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Repair Difficulty

Hard 4/5

Required Part

Outlet NTC Temperature Sensor / Main Control PCB
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