What does the Viessmann Vitodens 111-W F100 fault code mean?
The F100 fault code on the Viessmann Vitodens 111-W indicates an issue with the domestic hot water (DHW) firmware. This typically suggests that the control system managing the DHW is malfunctioning or requires an update.
Common Causes
- Outdated Firmware: The firmware controlling the DHW may be outdated and needs to be updated to the latest version.
- Corrupted Firmware: The firmware could be corrupted due to a power surge or improper installation, leading to malfunction.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves firmware that requires specialized knowledge and tools to diagnose and rectify safely.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F100 fault code is around £150 to £250. This includes potential firmware updates and diagnostic checks performed by a qualified engineer.