E20
Alpha Configuration / Parameter Error

Boiler displays E20 and will not operate; may occur after service mode or parameter changes.

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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

Incorrect installer parameter settings, Incompatible accessory configuration, Corrupted EEPROM on PCB

How to Fix / Troubleshooting

Safety: Only trained personnel should alter installer parameters.

  • Power reset: Turn off the boiler at the mains for 60 seconds, then turn back on to see if E20 clears.
  • Restore default settings (qualified person): Using the installer menu, reset parameters to factory defaults as per the Alpha installation manual.
  • Check accessories: Ensure any connected accessories (e.g., weather compensation sensor, OpenTherm controls) are compatible and correctly wired.
  • PCB replacement: If configuration cannot be restored, the PCB may need replacement and reprogramming by an Alpha engineer.
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Repair Difficulty

Professional Required 5/5

Required Part

Main Control PCB
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