What does the Viessmann Vitodens 100-W F35 fault code mean?
The F35 fault code on the Viessmann Vitodens 100-W indicates a problem with the gas pressure supply to the boiler. This can prevent the boiler from operating efficiently or at all, leading to heating and hot water issues.
Common Causes
- Low Gas Pressure: Insufficient gas supply from the mains can cause the boiler to fail to ignite or operate correctly.
- Blocked Gas Supply Line: Obstructions in the gas line can restrict flow, leading to pressure issues that trigger the fault code.
Can I fix it myself? (DIY)
It is highly recommended to call a Gas Safe Engineer to diagnose and resolve gas pressure issues, as working with gas appliances can be dangerous and requires professional expertise.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving a F35 fault code could range from £150 to £300, depending on whether the issue is a simple adjustment or requires replacement of components like the gas valve or pressure regulator.