Vokera water heater shows code 18, appliance indicates expansion or pressure-related fault
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: Hot water under pressure can cause scalding. Allow the system to cool before working on pressure components.
User checks:
- Observe the pressure gauge as the system heats. If it rises from around 1 bar cold to over 3 bar hot, the expansion vessel may be faulty.
- Check for discharge from the pressure relief valve outlet pipe outside.
Engineer steps:
- Isolate and drain pressure from the system, then measure and recharge the expansion vessel to the specified pre-charge (often around 0.8–1.0 bar).
- If the vessel will not hold charge, replace the expansion vessel.
- Inspect and, if necessary, replace the pressure relief valve if it continues to leak after pressure is corrected.
Incorrect handling of pressurised components can be dangerous; use a qualified engineer.
Repair Difficulty
Required Part
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