F24 High
Your boiler has stopped working because the water returning from your radiators has become too hot, which usually means the water isn't circulating properly through the system.
Technical description: Central heating return temperature is greater than90°C
Typical repair cost: £120-350 (including labour)
DIY fix possible
Check that all radiator valves (TRVs) are fully openEnsure the boiler pressure is between 1.0 and 1.5 barCheck if any bypass valves in your pipework are accidentally closed
Protect yourself from future repair bills
A boiler cover plan would cover faults like F24 — no call-out fees, no surprises.
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Parts commonly replaced
- Circulation pump
- NTC return temperature sensor
- Main heat exchanger (flushing service)
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