What does the Baxi Platinum F78 fault code mean?
The F78 fault code on a Baxi Platinum boiler indicates that the domestic hot water (DHW) return temperature is too high, which can lead to inefficient operation and potential damage. This fault typically suggests an issue with the temperature sensor or a blockage in the system.
Common Causes
- Blocked Heat Exchanger: A blockage can restrict water flow, causing the return temperature to rise excessively.
- Faulty Temperature Sensor: If the temperature sensor is malfunctioning, it may incorrectly read high temperatures, triggering the fault code.
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 handling. Attempting to fix it yourself could pose safety risks.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F78 fault could be around £150 to £250, primarily depending on whether the temperature sensor needs replacement or if the heat exchanger requires cleaning or replacement.