Boiler displays E10, system pressure may be high or low, safety valve may discharge water.
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: Allow the system to cool before releasing any pressure. Hot water under pressure can cause scalding.
User-level checks:
- Check the pressure gauge. If above 2.5–3.0 bar when cold, bleed a radiator to reduce pressure to around 1.2 bar.
- Ensure the filling loop valves are fully closed and disconnected if removable.
Technical checks (qualified personnel):
- Check the expansion vessel pre-charge with the system drained; recharge with nitrogen/air to the specified pressure (typically around 0.8–1.0 bar).
- If water comes out of the Schrader valve, the vessel diaphragm has failed and the vessel must be replaced.
- Inspect the connection pipe between the vessel and system for blockage.
- Test the safety valve for correct opening pressure and reseating; replace if it continues to drip.
After repairs, refill and vent the system, then verify stable pressure during heating operation.
Repair Difficulty
Required Part
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