49
11
Failure internal com-
munication bus
Check:
- cable connections on MCBA board
- if there is moisture on the display
- for external EMC influences
18
Flow temperature
too high
Check:
- pump
operation
- the water flow,
see Par. 4.6.6
- whether the installation has been properly vented
- the flow and return sensors for defects
-
the water pressure (min 0.8 bar)
19
Return temperature
too high
24
Return temperature
higher than flow
Check:
- flow and return temperature sensor wiring
- flow and return connections
-
direction of flow - pump is the right way round
-
flow and return crossed
31
Flow temperature
sensor error
Flow temperature sensor short-circuited.
32
Return temperature
sensor error
Return temperature sensor short-circuited.
36
Flow temperature
sensor error
Flow temperature sensor not connected or defective.
37
Return temperature
sensor error
Return temperature sensor not connected or defec-
tive.
77
Ionisation signal loss
during operation (
after 4 restarts during
1 heat demand)
Check:
- re-circulation of flue gas (internal leakage or outlet
construction/position incorrect).
- insufficient air transport due to blockage.
- adjustment of the boiler is incorrect.
- low fire percentage set point and increase.
43
Parameters out of
range
Check:
the parameters in the memory.
Other
codes
Control unit failure
After recording the ‘flashing’fault code numbers:
- First press reset
- If the fault returns, record the code again, check
the wiring for possible short-circuit or wrong con-
nections
-
If the fault continues to occur, exchange the con-
trol unit
Table 11 Failure codes
