Fault Finding - Bosch Worcester Greenstar Ri ErP + Series Installation And Maintenance Instructions Manual

8.1

Fault finding

Blue light Fault
indication
No light No power at control
board
Light ON Appliance ON but not
operating during demand
Slow flash Ignition lockout
(mostly off,
flashes on)
Slow flash Flue overheat
(mostly on,
flashes off)
Heat exchanger overheat ▶ Check
Flue pressure switch
Fast flash Volatile lockout (sensor,
fan or code plug)
2 pulses
5 pulses
Table 35 Fault finding
6 720 821 670 (2018/06)
Possible solution/check
▶ Check
– Mains supply voltage to the appliance.
– Appliance mains switch is ON.
– Fuse F1 - 2A Slow blow.
▶ Replace control board.
▶ Check
– Live demand at ST2 terminal (L
– Manual bypass is open.
– If Central Heating is working, check Hot Water controls.
– If Hot Water is working, check Central Heating controls (i.e. external diverter valve, room
thermostat/programmer, frost thermostat).
▶ Replace control board.
▶ Check
– Gas present and at the correct pressure?
– Gas valve:
• Is there 29V d.c. to each solenoid?
• The resistance of each solenoid ( 9.3.4).
– Combustion CO2 level.
– Blockage or restriction in the flue.
– Gas valve adjustment.
– Ignition electrodes/harness/connections.
• Condition and resistance of the leads (approximately 2,100 Ω).
▶ Replace control board.
Flue temperature too high.
▶ Check heat exchanger baffles are correctly fitted or removed and not refitted
– Water pressure.
– All air is vented.
– Pump/harness/connections.
– Water leaks/blockage.
– Safety thermostats/low voltage wiring harness/connections.
– Blocked heat exchanger.
▶ Replace control board.
▶ Check for blockage in the flue system.
▶ Check
– Temperature sensors:
• Condition and resistance of the leads.
• Resistance of sensor ( 9.3.1).
– Fan.
• 230V A.C. across the live (purple) and neutral (brown)
– Fan lead continuity.
– Code plug.
• Is code plug missing or not inserted properly?
▶ Check
– Service mode switch is in "MIN" position?
▶ Return mode switch to "NORM" position if minimum test mode not required.
▶ Check
– Service mode switch is in "MAX" position?
▶ Return mode switch to "NORM" position if maximum test mode not required.
FAULT FINDING AND DIAGNOSIS
) - is there a demand?
R
59