What does the Vaillant ecoTEC exclusive F78 fault code mean?
The F78 fault code indicates a problem with the hot water demand system in the Vaillant ecoTEC exclusive boiler. This typically means that the boiler is unable to detect a request for hot water, which can lead to a lack of hot water supply.
Common Causes
- Faulty Flow Sensor: The flow sensor may be malfunctioning, preventing the boiler from recognizing the demand for hot water.
- Wiring Issues: Damaged or loose wiring connections related to the hot water system can disrupt communication between components.
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 to ensure safety and compliance with regulations.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F78 fault could be around £150 to £250, primarily due to potential replacement of the flow sensor and associated labour costs.