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Blue Light Indication | Fault | Possible Solution/Check |
No light | No power at control board |
Permanent mains supply to boiler. Boiler mains switch ON. Fuse F1 - 2A Slow blow. Fuse F2 - 1.25A Anti-surge. Transformer (both coils below 100 . Otherwise replace control board |
Light ON | Boiler ON but not operating during demand |
Live demand at ST2 terminal LR - is there a demand? Manual bypass is open. If CH is working check HW controls. If HW is working check CH controls (i.e. external diverter valve, frost stat, room stat/programmer. Otherwise replace board. |
Slow flash (mostly off, flashes on) | Ignition lockout |
▶ Gas present and at correct pressure? ▶ Gas valve – Check that there is 35V d.c. to each solenoid – Check the resistance of each solenoid: Top solenoid = 380 + 10% (342 - 418 ) Bottom solenoid = 190 + 10% (171 - 209) ▶ Combustion CO2 level. ▶ Flue condition. – Blocked flue? ▶ Blocked condensate pipe or frozen condensate. ▶ Gas valve adjustment. ▶ Ignition electrodes/harness/connections. – Check for condition and resistance of leads (approximately 2100 ) ▶ Otherwise replace control board |
Slow flash (mostly on, flashes off) |
Flue overheat (Top 2 Solutions) Heat exchanger overheat (Middle 7 solutions) Flue pressure switch (Bottom solution) |
Flue temperature too high. ▶ Heat exchanger baffles removed and not refitted. ▶ Heat exchanger blocked ▶ Water pressure ▶ All air vented ▶ Pump/harness/connections. ▶ Water leaks/blockage ▶ Safety thermostats/low voltage wiring harness/connections ▶ Otherwise replace control board Blockage in the flue system |
Fast flash | Volatile lockout (sensor, fan or code plug) |
▶ Temperature sensors – Check condition and continuity of leads – Check resistance of sensor (8k - 20k ) ▶ Fan – 230V A.C. across the live (purple) and neutral (brown) ▶ Fan lead – Check continuity ▶ Code plug – Is code plug missing or not inserted properly |
2 pulses | Service mode switch in min. position | |
5 pulses | Service mode switch in max. position |