F.24 High
Your boiler has shut down because the water inside is heating up much faster than it can be moved around the system, usually due to a blockage or a pump issue.
Technical description: Safety switch-off – temperature rise too fast
Typical repair cost: £150-£350 (including labour)
DIY fix possible
Ensure all radiator valves (TRVs) are fully openCheck that the boiler pressure is between 1.0 and 1.5 barPress the reset button once to see if the fault clears
Protect yourself from future repair bills
A boiler cover plan would cover faults like F.24 — no call-out fees, no surprises.
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Parts commonly replaced
- Circulation Pump
- Primary Heat Exchanger (Cleaning/Flush)
- Temperature Sensors (NTC Thermistors)
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