BoilerFaultCodesTechnical description
Hot water fault over-flow pipe
What causes this fault?
This fault occurs when the internal pressure within your boiler gets too high, forcing the safety valve to open and release water to prevent damage. The most common reasons are a loss of air in the expansion vessel or a buildup of limescale preventing the safety valve from closing properly. Since the system has lost water and pressure, the boiler shuts down to protect itself from overheating.
This issue often surfaces in autumn when the heating is turned on for the first time after summer, as the expansion vessel may have lost its charge during the 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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