BoilerFaultCodesTechnical description
Safety thermostat or flue thermostat tripped
What causes this fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety sensor to cut the power. The most common reasons are a failed pump stopping water from moving or a blockage in the heat exchanger caused by a buildup of sludge and debris.
This issue often appears when the heating is first turned on after summer, as the internal pump can seize up after 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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