BoilerFaultCodesTechnical description
Safety Thermostat Operated
What causes this fault?
This fault occurs when the internal safety sensors detect that the water inside the boiler has reached an unsafe temperature, triggering an automatic shutdown to prevent damage. The most common reasons are a pump failure that stops water from moving or a buildup of sludge and debris that creates a blockage in the heat exchanger.
This issue often surfaces when the heating is first turned on after summer, as the internal pump can seize up from months of inactivity.
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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