What does the Glow-worm Betacom F99 fault code mean?
The F99 fault code indicates a problem with the domestic hot water (DHW) inlet pressure, which may prevent the boiler from functioning correctly. This fault typically arises when the pressure is too low or there is a blockage in the water supply.
Common Causes
- Low Water Pressure: Insufficient pressure in the water supply can trigger this fault code, often due to leaks or issues with the mains supply.
- Blocked Inlet Filter: A blockage in the inlet filter can restrict water flow, leading to inadequate pressure and the F99 error.
Can I fix it myself? (DIY)
If you are comfortable, check the water pressure gauge on the boiler; it should typically be between 1-1.5 bar. If it’s low, you can top up the system using the filling loop. However, if the issue persists or involves gas components, it is crucial to call a qualified Gas Safe Engineer.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F99 fault could be around £150-£200, primarily for checking and possibly replacing the inlet filter or rectifying low water pressure issues. This cost reflects the need for a professional assessment and potential parts replacement.