BoilerFaultCodesYour boiler has switched itself off because it has detected that the water inside has become or is at risk of becoming too hot.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety Thermostat
What causes this fault?
This fault occurs when the water temperature inside the boiler exceeds a safe limit, triggering a safety shut-off to protect the internal components. It is most commonly caused by a circulation problem, such as a failing pump or a blockage, which prevents the heated water from leaving the boiler quickly enough.
This issue is more frequent during the first cold spell of autumn, when pumps that have been idle all summer often seize or struggle to move heavy sludge.
DIY fix possible
Check that your radiator valves are open and not blocked by furniture.Ensure there is enough water pressure by checking the gauge is between 1 and 1.5 bar.Turn the selector switch to the reset position for five seconds and then back to the original setting.
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 24 — no call-out fees, no surprises.
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Potterton Performa 28i 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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