What does the Viessmann Vitodens 111-W F64 fault code mean?
The F64 fault code indicates a malfunction in the domestic hot water (DHW) flow sensor of the Viessmann Vitodens 111-W boiler. This issue can prevent the boiler from properly detecting water flow, leading to inadequate hot water supply.
Common Causes
- Faulty Flow Sensor: The flow sensor may be defective or damaged, causing incorrect readings.
- Blockage in Water Flow: A blockage in the water supply line can hinder the flow sensor’s ability to function correctly.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves gas and electrical components that require professional expertise. Attempting to fix it yourself could pose safety risks.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing the DHW flow sensor is around £150 to £250. This includes the cost of the part and labour, as flow sensor replacements typically require professional installation.