E19
Alpha Plate Heat Exchanger Temperature Differential Fault

Boiler shows E19; may occur intermittently, often during hot water draw-off.

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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

Blocked plate heat exchanger, Limescale build-up, Poor primary circulation, Faulty DHW NTC sensor

How to Fix / Troubleshooting

Safety: Isolate power and water supplies. Components may be hot.

  • Check system pressure and circulation: Ensure correct pressure and that radiators heat evenly, indicating good primary flow.
  • Descale plate heat exchanger (qualified person): Remove the plate heat exchanger and flush it with a suitable descaling solution until flow is restored.
  • Clean system filter: If fitted, clean the Alpha magnetic filter to improve primary water quality.
  • Verify DHW sensor: Test and replace the DHW NTC if readings are unstable.

Severe scaling may require replacement of the plate heat exchanger.

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Repair Difficulty

Hard 4/5

Required Part

Plate Heat Exchanger
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