Fault finding and diagnosis
77
Greenstar 2000 – 6 721 820 552 (2021/02)
263 V Program sequence error ▶ Restart the appliance to see if the problem re-occurs.
▶ Check the electrical connections on the board (check for loose wires etc.).
▶ Check the code plug, if present, is not damaged.
▶ Replace the code plug, if present and required.
▶ Replace the control unit (PCB).
264 B Air handling failed during operation ▶ Reconnect the fan plug properly, perform reset.
▶Replace fan.
▶ Mains voltage must correspond to the default value.
▶ Remove any blockages in the flue system.
▶ Check venturi/injector for potential blockage.
265 O Heat demand lower than energy supplied Operating message, is not a fault.
268 O Relay test was activated Operating message, is not a fault.
269 V Flame monitoring ▶ Restart the appliance to see if the problem re-occurs.
▶ Check the electrical connections on the board (check for loose wires etc.).
▶ Replace the control unit (PCB).
270 O Starting up boiler Operating message, is not a fault.
273 O Operation of burner and fan interrupted Operating message, is not a fault.
275 O Boiler electronics in test mode Operating message, is not a fault.
281 B Pump pressure increase too low ▶ Check the flow pressure in system.
▶ Check the system for circulation issues (air locks, blockage, restriction).
▶ Check that the tacho/PWM plug, if present, for the circulation pump is fitted correctly.
▶ Check the tacho/PWM cable, if present, for continuity and replace the tacho/PWM cable
if required.
▶ Replace the pump.
283 O Burner starting Operating message, is not a fault.
284 O Opening air/gas ratio control valve/oil
solenoid valves
Operating message, is not a fault.
305 O Boiler in hot water anti-cycle mode 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.
306 V Flame signal after closing the fuel supply 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.
323 – BUS signal cannot be processed ▶ Check connection to EMS controls, including 2-core cable if hard-wired.
▶ Check and replace PCB.
328 V Brief mains voltage failure ▶ Check for voltage interruption between electrical wiring system of the building and the
appliance.
341 B Temperature rise at boiler too rapid ▶ Open isolation valves.
▶ Connect plug to pump.
▶Replace pump.
▶ Ensure circulating pump is set on Constant speed mode - curve III.
342 B Temperature rise during hot water mode too
rapid
▶ If the water pressure is too low, top up with water and vent the system.
▶ Ensure isolation valves are open
▶ Check and replace diverter valve
350 B Short-circuit at flow temp. sensor ▶ Check and replace flow temperature sensor and harness Section 13.2.
▶ Check and replace the connecting lead to the flow temperature sensor.
▶ Check and replace control unit/burner control unit.
351 B Flow temp. sensor interrupted ▶ Connect the plug to the flow temperature sensor.
▶ Check and replace flow temperature sensor and harness Section 13.2.
▶ Check and replace the connecting lead to the flow temperature sensor.
▶ Check and replace control unit/burner control unit.
353 – Test non-volatile lockout Device may not start temporarily, never been off for 20 min for 24 h.
354 – Test volatile lockout Overpressure setting is detected.
356 B Power supply for the boiler is too low ▶ Establish supply voltage of at least 196 VAC.
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