BoilerFaultCodesTechnical description
Safetyswitch-off:Temp.incr.toofast | Pumpblocked,insufficientpumpoutput,airinproduct,systempressure toolow,non-returnvalveblocked/incorrectlyinstalled
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the temperature is rising too rapidly, which usually means heat isn't being carried away from the heat exchanger. The most common reasons are that there isn't enough water pressure to move the heat, air bubbles are trapped in the pump, or the pump itself has seized and stopped circulating water. Basically, the boiler is producing heat faster than the system can distribute it to your radiators.
This issue often appears in autumn when the heating is turned back on for the first time after summer, as internal pump components can seize up 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.