What does the Glow-worm Ultimate F73 fault code mean?
The F73 fault code on the Glow-worm Ultimate indicates a domestic hot water (DHW) temperature error, which typically means that the boiler is unable to achieve or maintain the desired water temperature. This can lead to insufficient hot water supply for taps and showers.
Common Causes
- Faulty DHW Temperature Sensor: The sensor may be malfunctioning, providing incorrect readings to the control system.
- Blocked Heat Exchanger: A blockage in the heat exchanger can prevent proper heat transfer, affecting water temperature.
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 DIY repairs could be dangerous.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F73 fault could be around £150-£250, depending on whether the DHW temperature sensor needs replacing or if the heat exchanger requires cleaning or replacement.