Boiler shows E11, heating may work but hot water does not, or vice versa.
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.
Possible Causes
How to Fix / Troubleshooting
Safety first: Isolate power and close water isolation valves before removing any hydraulic components.
User-level checks:
- Run hot water and then heating separately to confirm which mode fails.
- Reset the boiler and observe if the fault is intermittent.
Technical checks (qualified personnel):
- Access the diverter valve assembly and check the actuator for movement when switching between DHW and CH demand.
- Manually exercise the valve (if possible) to free minor sticking; if resistance is high, replace the valve cartridge or complete assembly.
- Inspect and clean strainers/filters in the hydraulic circuit to remove debris.
- Test any position microswitches or feedback sensors and replace if faulty.
After repair, test both heating and hot water modes to ensure correct valve operation.
Repair Difficulty
Required Part
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