BoilerFaultCodesTechnical description
Flow temperature steep rise – the radiator valves may not be open enough to circulate water
What causes this fault?
This fault occurs when the heat generated by the burner cannot be carried away because the water is not moving through the system fast enough. The most common reason is that too many radiator valves are turned off or blocked, causing the internal temperature to spike dangerously high in a matter of seconds. In some cases, it may also indicate that the pump is beginning to fail or the system has become restricted by debris.
This code often appears during the first few cold days of autumn when homeowners turn their heating back on but find their radiator valves have seized shut 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.