BoilerFaultCodesTechnical description
Safety Thermostat
What causes this fault?
This fault occurs when the water inside your boiler reaches a temperature that is too high, triggering a safety switch to cut the power. The most common reasons are a pump failure preventing water from circulating or a buildup of sludge and limescale that blocks the heat exchanger. It acts as a vital safety feature to prevent the internal components from being damaged by extreme heat.
This issue often surfaces when the heating is first turned on after summer, as the 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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