E20
Attack
Circulation Pump / Flow Fault
Boiler displays E20; may be associated with pump or flow switch malfunction.
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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
Seized Attack circulation pump, Blocked system filter or strainer, Airlock in primary circuit, Faulty flow switch (if fitted)
How to Fix / Troubleshooting
Safety: Turn off power and allow the boiler to cool before touching the pump.
Steps:
- Bleed pump: Loosen the bleed screw on the front of the Attack pump (if present) to release trapped air. Have a cloth ready for small water drips.
- Free the impeller: Insert a screwdriver into the pump shaft slot and gently turn to free a stuck impeller.
- Clean filters: Check and clean any magnetic or mesh filter on the return line to the boiler.
- Reset and test: Restore power, reset the boiler, and check if circulation starts.
Technician: If the pump does not run or E20 returns, the pump or PCB should be tested and possibly replaced by a professional.
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Repair Difficulty
Medium
3/5
Required Part
Heating Circulation Pump
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