Fault finding and diagnosis
Greenstar 4000 – 6 720 891 162 (2020/09)
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Table 31 Indicators and fault displays
10.1.3 Faults that are not displayed
Table 32 Faults that are not shown on the display
2970 B
Pressure drop in heating system too rapid
Too many unexpected pressure drops within a short time period.
Cause code can appear if system is pressurised and the system then vented.
▶ Re-pressurise manually and vent the system.
▶ Ensure the correct pressure. If cause code does not clear, power off appliance.
2971 B
System pressure too low
System pressure is very or extremely low. This is triggered when the pressure falls to
between 0.6 and 0.3 bar. Top up water until the target pressure is reached.
Filling loop
▶ Vent the heating system and top up water until the pre-set pressure reached.
Pressure sensor
▶ Check the continuity down harness for the pressure sensor and replace if required.
▶ Check the voltage at the pressure sensor and replace if required.
2972 V
Mains voltage too low
▶ Establish supply voltage of at least 196 VAC.
▶ Replace control unit.
3071
–
C II RF
▶ Check the configuration (address setting). The selected setting requires a hard-wired
room control.
▶ Check the EMS connection cable of the room control for damage. The BUS voltage on
the room control must be between 12 and 15 V DC.
▶ Disconnect the EMS-BUS connection to the control unit and power the boiler off and
back on again. Reconnect the EMS-BUS connection.
▶ If the problem persists the room control may be defective.
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ry Fault text on the display, description
Remedy
Appliance faults
Remedy
Combustion noises too loud; rumbling noises
▶ Check the gas type.
▶ Check the gas supply pressure.
▶ Check the flue system; clean or repair if required.
▶ Check the gas/air ratio.
▶ Check the gas valve; replace if required.
Flow noises
▶ Set the pump rate or pump characteristic map correctly and match to the maximum
output.
Heat-up takes too long.
▶ Set the pump rate or pump characteristic map correctly and match to the maximum
output.
Flue gas values incorrect; CO content too high.
▶ Check the gas type.
▶ Check the gas supply pressure.
▶ Check the flue system; clean, repair or replace if required.
▶ Check the gas/air ratio.
▶ Check the gas valve; replace if required.
Delayed ignition, poor ignition.
▶ Check the ignition transformer function for misfiring in the
Function check
menu
Ignition
test, replace if required.
▶ Check the gas type.
▶ Check the gas supply pressure.
▶ Check the power supply.
▶ Check the electrodes with cable; replace if required.
▶ Check the flue system; clean or repair if required.
▶ Check the gas/air ratio.
▶ For natural gas: check the external gas flow monitor, replace if required.
▶ Check the burner, replace if required.
▶ Check the air/gas ratio control valve; replace if required.
Condensate in air box
▶ Check the non-return valve in the burner hood assembly, replace if required.
System boilers: hot water outlet temperature is too low.
▶ Check the cylinder temperature setpoint.
System boilers: no hot water.
▶ Check the external controls function; replace if required.
No function, the display remains dark.
▶ Check the electrical wiring for damage.
▶ Replace defective cables.
▶ Check the fuse, replace if required. One spare fuse is supplied.
