BoilerFaultCodesTechnical description
Safety Thermostat Operated
What causes this fault?
This fault occurs when the water temperature inside your boiler gets too high, triggering a safety switch to prevent damage. The most common reason is a lack of water flow, often caused by a failing pump or a blockage within the main heat exchanger. It can also happen if there is trapped air in the system or if the internal safety sensor itself has developed a fault.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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