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Fault finding and diagnosis
Description
275 O
Boiler electronics in test mode
283 O
Burner starting
284 O
Opening air/gas ratio control valve/oil
solenoid valves
285 B
Return temperature is too hot
305 O
Heat exchanger in hot water anti-cycle
mode
306 V
Flame signal after closing the fuel supply
341 B
Temperature rise at heat exchanger too
rapid
347 B
Return temp exceeds flow temp for over
20 sec
351 B
Flow temperature sensor interrupted
353
–
Test non-volatile lockout
357 O
Ventilation program
358 O
Anti-seizing functn. active
360 V
Incomparable code plug
362 V
Boiler identification module or boiler
electronics faulty
363 V
Ionisation current did not drop during
ionisation test
364 V
Solenoid valve ev2 leaking.
365 V
Solenoid valve ev1 leaking.
522 O
NTC Drift Test is running
604 V
System fault burner control unit
90
Remedy
Operating message, is not a fault.
Operating message, is not a fault.
Operating message, is not a fault.
▶ Check the return temperature sensor.
▶ Check circulation pump.
Anti-fast cycle mode, domestic hot water keep warm function.
▶ Diverter valve is held in the hot water position for a period of time.
▶ Check for false demands on the cold water inlet.
Tip: Ensure the working pressure returns immediately to the standing pressure when the
gas valve closes.
▶ Check the gas supply to the property and the inlet on the gas valve (check drop on inlet).
▶ Check the gas valve is not passing and replace if required.
▶ Replace the PCB.
▶ Open isolation valves.
▶ Confirm sufficient flow.
▶ Connect plug to pump.
▶ Replace pump.
▶ Ensure circulating pump is set on Constant speed mode - curve III.
▶ Check the flow and return temperature sensor.
▶ Check circulation pump.
▶ Connect the plug to the flow temperature sensor.
▶ Check and replace flow temperature sensor and harness.
▶ Check and replace the connecting lead to the flow temperature sensor.
▶ Check and replace control unit/burner control unit.
Device may not start temporarily, never been off for 20 min for 24 h.
Operating message, is not a fault: Venting program has been activated.
Operating message, is not a fault: blocking protection for the heating pump and the 3-way
valve is active.
If code plug is present:
▶ Check that correct plug is inserted.
▶ Check the code plug is not damaged.
▶ Replace the code plug if required.
If code plug is not present:
▶ Check appliance electronics (PCB), replace if necessary.
▶ Wrong code plug is inserted.
▶ Check the code plug is not damaged.
▶ Replace the code plug if required.
▶ Check and replace the ionisation cable electrode assembly.
▶ Check and replace the electrodes if required.
▶ Check and replace the control unit.
▶ Check the gas valve, replace if required.
▶ Check electrodes and connecting leads, replace if required.
▶ Check and replace the control unit.
▶ Check the gas valve, replace if required.
▶ Check electrodes and connecting leads, replace if required.
▶ Check and replace the control unit.
▶ Check the difference between return and supply temperature value.
▶ Reset appliance - factory reset.
▶ If the fault persists following a reset, the burner control unit is faulty and must be
replaced.
Greenstar 1000 – 6721835943 (2023/08)
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