BoilerFaultCodesYour boiler has shut down because it is heating up much faster than it can circulate the water, usually due to a blockage or a pump issue.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety switch-off: Temp. incr. too fast - Temperature increase too fast
What causes this fault?
This fault occurs when the boiler detects that the water inside the unit is getting too hot, too quickly, suggesting the heat isn't being carried away to your radiators. It is usually caused by a pump failure, a blockage caused by sludge buildup, or air trapped within the system preventing proper water flow. Effectively, the boiler is forced to shut down to prevent the internal components from overheating and sustaining damage.
This issue is more frequent in autumn when the heating is turned on for the first time after summer, as pumps can seize and debris often settles while the system is inactive.
DIY fix possible
Check that all radiator valves (TRVs) are fully open to allow water to flow.Check the boiler pressure gauge and top it up to 1.5 bar if it is too low.Try resetting the boiler using the flame/reset button.
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A boiler cover plan would cover faults like F.24 — no call-out fees, no surprises.
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