What does the Viessmann Vitodens 200-W F55 fault code mean?
The F55 fault code on the Viessmann Vitodens 200-W indicates a problem with the expansion vessel, which is responsible for maintaining system pressure and absorbing fluctuations in water volume. A faulty expansion vessel can lead to pressure issues, potentially causing the boiler to shut down to prevent damage.
Common Causes
- Loss of Air Pressure: The air charge in the expansion vessel may have diminished, leading to inadequate pressure regulation.
- Water Leakage: A rupture or leak in the expansion vessel can result in water entering the air chamber, compromising its function.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as working on the expansion vessel involves handling pressurized systems and could pose safety risks if not done correctly.
Estimated Repair Cost (2026 UK Prices)
The estimated cost to replace a faulty expansion vessel on a Viessmann Vitodens 200-W is approximately £250 to £350. This includes parts and labour, as the expansion vessel is a critical component that requires professional installation to ensure safety and compliance with regulations.