Bosch GWH 345 ESR-N Manual page 35

Fault Indication
AA
LED or LCD of the appliance doesn't
start up, no function.
Noise; boiling noise (over heating).
No heating function.
No DHW function.
Table 18
1) Check connections, fuse or if there are visible damages.
Error lock-out is indicated by the orange LCD blinking. An error lock-out is done for safety reasons. After fixing the
problem, press the reset button to return the heater to service.
6 720 607 909
Possible Cause
Flow reduced
No voltage supply, fuse
transformer etc. defect
Low circulation, air inside installation,
bad heat transfer.
No heat demand by the thermostat,
thermostat set too low, other defect.
No heat demand by the 12kohm
thermistor or aquastat.
Check
• 1. Check heat exchanger - flush or
descale if necessary
blown, • 1. Check voltage supply
• 2. Check fuse
• 3. Check control unit
• 1. Check for air in system, purge if
detected
• 2. Check circulators for proper oper-
ation
• 3. Check heat exchanger for block-
age or scale deposits
• 4. Check gas type, injectors, gas
valve
•
5. Verify heater is not in service
mode.
• 1. Check thermostat position
• 2. Check control unit
• 1. Check thermistor cable
• 2. Check Domestic hot water
thermistor or aquastat on tank
• 3. Check control unit
Troubleshooting
.
1)
.
1)
.
1)
.
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