BoilerFaultCodesYour boiler is overheating because water isn't moving through the system quickly enough to take the heat away.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Water level low Temperature rises too fast | Cause: Pump obstructed, pump running at lower capacity, ir in appliance, system pressure too low, flow and backflow NTC reversed
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the temperature is rising far too quickly, indicating that the heat isn't being carried away from the heat exchanger. The most common reason is a failing or stuck circulation pump, though it can also be triggered by a significant air lock or a blockage in the pipework preventing water flow. Essentially, the boiler is protecting itself from damage by shutting down because the water inside it is standing still and boiling.
This issue often surfaces in autumn when the heating is turned back on for the first time, as pumps can seize up after sitting idle throughout the summer.
DIY fix possible
Check the pressure gauge and top up the system to 1.5 bar if it is too lowEnsure all radiator valves are fully openBleed your radiators and the pump to remove trapped air
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A boiler cover plan would cover faults like F.24 — no call-out fees, no surprises.
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Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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