Bosch Control 8311 - Page 28

Operating and fault displays
Control 8311/8313 – 6720859790 (2020/02)
28
Table 7 Unit troubleshooting
DHW remains cold Heating of DHW is stopped. Current
DHW temperature is below 40 °C.
• The set DHW temperature is set
incorrectly.
▶ Adjust the set DHW temperature.
• The time program has been set
incorrectly.
▶ Reprogram the
time program.
• The DHW temperature is not rising. ▶ Check whether the DHW circuit is
in automatic mode.
▶Phone Service.
Thermal disinfection failed Thermal disinfection has been
aborted.
• The output of the heat source is
insufficient, e.g. because other
heat consumers (e.g. heating
circuits) demand heat during
thermal disinfection.
• The temperature sensor is
incorrectly connected or faulty.
• The cylinder primary pump is
incorrectly connected or faulty.
• FM-MW module or control unit is
faulty.
• The draw-off quantity during
thermal disinfection is too high.
▶ Select the time for thermal
disinfection so that there is no
overlap with additional heat
demands.
▶Phone Service.
Manual operation activated Boiler is operating in accordance with
the specifications in manual operation
 Chapter 3.7.3, page 13.
• Manual operation activated ▶ Deactivate manual operation
 Chapter 3.7.3, page 13.
Flue gas test is active Control operates for max. 30 minutes
with higher flow temperature
 Chapter 3.7.2, page 12.
• Flue gas test is active ▶ Deactivate flue gas test
 Chapter 3.7.2, page 12.
Position test for temp. limiter
sensor activated
The boiler heats until the high limit
safety cut-out is triggered.
• High limit safety cut-out position
test was carried out.
▶ Release the key and
key.
▶ Reset control with
 Chapter 3.7.1, page 12.
Manual operation pump... – • A manual mode was activated. ▶ Deactivate manual operation.
...Temperature sensor
defective
Depending on the faulty sensor. ▶ Phone Service.
No voltage behind the internal
safeguard for ZM5311 burner
output
Burner is not going into operation. • Internal safety device of burner has
triggered.
• Current consumption by the
burner is too high.
▶Phone Service.
Display text/Observation/
Fault
Effect on the control characteristics Cause Remedy
reset