What does the Viessmann Vitodens 111-W F45 fault code mean?
The F45 fault code on the Viessmann Vitodens 111-W indicates a problem with the mixing valve, which is responsible for regulating the temperature of the water supplied to the heating system. This fault can lead to inefficient heating and may require immediate attention to restore proper function.
Common Causes
- Faulty Mixing Valve: The mixing valve may be stuck or malfunctioning, preventing it from properly mixing hot and cold water.
- Electrical Connection Issues: Loose or damaged wiring connected to the mixing valve can disrupt its operation and trigger the fault code.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as working with gas appliances can be dangerous. Attempting to fix electrical or gas-related problems without proper training can lead to safety hazards.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F45 fault code, including parts and labour, is approximately £250-£350. This cost reflects the need to replace the mixing valve and ensure proper installation by a qualified engineer.