BoilerFaultCodesTechnical description
Limit thermostat fault
What causes this fault?
This fault occurs when the water inside the heat exchanger reaches a dangerously high temperature, triggering a safety switch to prevent damage. The most common reasons are a pump failure that stops water from moving or a blockage in the system that prevents heat from escaping the boiler. It can also be caused by a faulty sensor sending an incorrect 'overheat' signal to the main control board.
This issue is more frequent when the heating is first turned on after summer, as pump components often seize up during long periods 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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