BoilerFaultCodesWhat the manual says
Manufacturer manualpump pre-run
From this model's manual
Verified against the Glow Worm/Glow Worm Glow Worm 30cxi installation & service manual, page 52.
What causes this fault?
This isn't actually a fault, but rather a normal part of the boiler's ignition sequence. It occurs when the system starts a 'pump pre-run' to ensure water is circulating correctly through the heat exchanger before the gas burner is allowed to light. This safety check prevents the boiler from overheating during the initial start-up phase.
DIY fix possible
This fault may be fixable without an engineer. Check your manual first.
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