What does the Glow-worm Ultimate F74 fault code mean?
The F74 fault code indicates a domestic hot water (DHW) pressure error in the Glow-worm Ultimate boiler. This typically means that the pressure in the system is either too low or too high, affecting the boiler’s ability to provide hot water efficiently.
Common Causes
- Low Water Pressure: This can occur due to leaks in the system or insufficient water supply, leading to inadequate pressure for hot water production.
- Faulty Pressure Sensor: A malfunctioning pressure sensor may incorrectly read the water pressure, triggering the F74 fault code.
Can I fix it myself? (DIY)
If you are comfortable, you can check the pressure gauge on your boiler; it should typically be between 1-1.5 bar. If it’s low, you can re-pressurise the system using the filling loop. However, if you suspect a faulty sensor or if the issue persists, it is crucial to call a Gas Safe Engineer.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F74 fault code is around £150-£250. This includes potential replacement of the pressure sensor and any necessary labour costs, which are justified by the complexity of diagnosing and fixing pressure-related issues in a boiler.