BoilerFaultCodesYour boiler is heating up much faster than it should and has shut down to prevent itself from overheating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: The rate of temperature rise measured by the heating flow thermistor is too high.
What causes this fault?
This fault occurs when the water inside the boiler gets hot too quickly because it isn't moving away from the heat source fast enough. The most common reasons are a pump that has failed or become stuck, or a blockage within the main heat exchanger that is restricting water flow.
This issue is more frequent in autumn or winter when the heating is first turned on after a long summer break, as pumps can often seize up from lack of use.
DIY fix possible
Check if your radiator valves are openEnsure your boiler pressure is between 1.0 and 1.5 barGently bleed your radiators to remove any trapped air
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 25 — no call-out fees, no surprises.
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Glow-worm Energysaver Combi 2 80 100 is discontinued — time for a new one?
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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