What does the Glow-worm Energy F78 fault code mean?
The F78 fault code on a Glow-worm Energy boiler indicates a problem with the central heating (CH) diverter valve. This component is responsible for directing hot water to either the heating system or the hot water supply, and a fault can disrupt heating and hot water delivery.
Common Causes
- Stuck Diverter Valve: The valve may be stuck in one position due to debris or wear, preventing it from functioning correctly.
- Electrical Fault: Issues with the wiring or connections to the diverter valve can lead to communication failures, causing the fault code to trigger.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as working on gas appliances can be dangerous. Attempting to fix electrical or gas-related problems without proper training can lead to serious safety risks.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for a diverter valve replacement on a Glow-worm Energy boiler is around £300 to £400. This includes parts and labour, as diverter valves can be complex to replace and may require additional diagnostics.