What does the Glow-worm Ultimate F89 fault code mean?
The F89 fault code on the Glow-worm Ultimate indicates a problem with the domestic hot water (DHW) valve. This alert suggests that the valve may be stuck or malfunctioning, preventing proper hot water flow.
Common Causes
- Stuck DHW Valve: The valve may be physically stuck due to debris or wear, hindering its operation.
- Electrical Issue: A fault in the electrical connections or the valve actuator can prevent the valve from opening or closing 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 handling for safety and compliance.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F89 fault may range around £150 to £250, primarily depending on whether the DHW valve needs cleaning, repair, or replacement, along with any associated labour costs.