BoilerFaultCodesTechnical description
Low flow condition - boiler will shut off and not lockout
What causes this fault?
This fault occurs when the temperature difference between the water leaving the boiler and returning to it becomes too wide, indicating that heat isn't being carried away fast enough. The most common reasons are a failing internal pump that can't push the water through, or a blockage caused by a buildup of sludge and debris in the system. When the water moves too slowly, it lingers in the heat exchanger and risks boiling, triggering a safety shutdown.
This fault is frequently noticed at the start of autumn when the heating is first turned on after summer, as pump components can seize 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.