E14
ACV DHW Overtemperature / Anti-Scald Protection

Boiler shows E14, DHW temperature overshoots or boiler cycles rapidly on hot water

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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

Scaled DHW heat exchanger, Faulty DHW NTC sensor, Sticking DHW thermostatic mixing valve, Incorrect parameter settings

How to Fix / Troubleshooting

Safety first: Risk of scalding. Test hot water temperature carefully and warn occupants.

  • Check DHW setpoint: On the ACV control panel, verify the DHW temperature is not set excessively high.
  • Run hot water: Open a hot tap fully and observe if the temperature stabilizes or fluctuates. Note any very hot bursts.
  • Descale fixtures: Limescale in taps and shower mixers can affect temperature. Clean or descale aerators and shower heads.
  • Professional service: A technician should descale or replace the DHW plate heat exchanger or tank-in-tank coil, test the DHW NTC, and check the thermostatic mixing valve on ACV storage models.
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Repair Difficulty

Medium 3/5

Required Part

DHW Plate Heat Exchanger
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