Bosch Installation Manual
Faults
Greenstar – 6721822579 (2021/01)
76
17.3 Faults that are not shown on the display
Table 37 Faults not shown on the display
Appliance faults Elimination
Combustion noise too loud; rumbling noises ▶ Insert code plug correctly; replace if defective.
▶Check gas type.
▶ Check inlet gas pressure; adjust if defective.
▶ Check flue gas system; clean or repair if defective.
▶ Check gas/air ratio in the combustion air and flue gas; replace gas valve if defective.
Flow noises ▶ Set pump speed correctly to match maximum output.
▶Set pump mode.
Heating-up takes too long ▶ Set pump speed correctly to match maximum output.
▶Set pump mode.
Flue gas readings incorrect; CO levels too high ▶Check gas type.
▶ Check inlet gas pressure; adjust if defective.
▶ Check flue gas system; clean or repair if defective.
▶ Check gas/air ratio in flue gas; replace gas valve if defective.
Violent ignition, poor ignition ▶ Check gas type.
▶ Check inlet gas pressure; adjust if defective.
▶Check power supply.
▶ Check electrodes for visual damage; replace if defective.
▶ Check flue gas system; clean or repair if defective.
▶ Check gas/air ratio; replace gas valve if defective.
▶ Check gas valve; replace if defective.
▶ Check burner; replace if required.
DHW has unpleasant odor or has a dark color ▶ Perform thermal disinfection of the DHW circuit.
▶ Replace sacrificial anode in the tank (if installed).
▶ Consult local water department.
Set supply temperature exceeded ▶ Switch off automatic anti-cycle timer, i.e., set value to 0.
▶ Set the required anti-cycle timer, e.g. default setting of 3 minutes.
Condensate in air box ▶ Insert diaphragm in the mixer unit per installation instructions; replace if defective.
DHW temperature is not reached (combi boiler ZWB...-3A
only)
▶ Insert code plug correctly; replace if defective.
▶ Check whether voltage (120 VAC) is present between terminal 1 and terminal 3;
repair if defective.
▶ Check turbine; replace if defective.
Heatronic is flashing (i.e. all buttons, all display segments,
burner indicator etc. are flashing)
▶ Replace fuse Si 3 (24 V) (6.3 A fuse according to IEC default).