BoilerFaultCodesYour boiler is heating up faster than the water can move away, which usually means something is blocking the flow or the pump isn't circulating water correctly.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flow temperature increased too quickly – check water circulation
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the heat exchanger is getting too hot, too quickly, because the heated water isn't being moved away fast enough. The most common reasons are a pump that has failed or become jammed, or a blockage in the system like trapped air or a build-up of sludge. Essentially, the boiler is producing heat but has nowhere to send it, so it shuts down to prevent internal damage.
This issue often appears in autumn when the heating is turned back on for the first time, as pumps can seize up after being idle over the summer months.
DIY fix possible
Check that at least two or three radiator valves are fully open.Ensure the central heating bypass valve is not closed.Check for any visible leaks around the boiler or pipework.Try resetting the boiler to see if the circulation clears.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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