BoilerFaultCodesWhat the manual says
Manufacturer manualLimit thermostat
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature, triggering a mechanical safety switch to cut off the burner. The most common reasons are a failed pump that isn't moving water efficiently, or a build-up of sludge and debris that is restricting flow through the heat exchanger.
This issue often surfaces in autumn when the heating is turned back on for the first time, as pump components can seize up after being idle over the summer.
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.
Avoid the next call-out bill
A cover plan would handle faults like RED LED Solid: no call-out fees, no surprise bills.
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