142
3.
Check the flue gas temperature sensor resistance.
See previous chapter. Replace faulty flue gas tem-
perature sensor if required.
4.
Turn off the ON/OFF switch.
5.
Turn the ON/OFF switch back on.
Restart the commissioning assistant.
6.
Check for leaks on the flue gas side.
Note
If fault message F.416 continues to be displayed
although the flue gas temperature sensor has been
correctly positioned: Initial commissioning may result in
burner faults e.g. caused by air in the gas line. Elimi-
nate the fault and unlock the device.
Information on replacing the HMU heat management unit and BCU burner control unit
If the burner control unit (BCU) is being replaced, com-
missioning is carried out with the "Service assistant"
software tool.
Spare part installation instructions and
Checking the cylinder loading plate heat exchanger
Note
During and after removal, small amounts of water may
trickle from the plate heat exchanger.
B
C
A
Fig. 95
1.
Shut off and drain the appliance on the heating
water and DHW (loading cylinder) sides. See
page 137.
2.
Undo 2 screws
A
. Pull plate heat exchanger
B
towards the back and lift out upwards.
3.
Check the connections on the heating water and
DHW sides for contamination and scaling; replace
the plate heat exchanger if necessary.
4.
Install in reverse order using new gaskets.
Checking the system separation plate heat exchanger
Note
During and after removal, small amounts of water may
trickle from the plate heat exchanger.
Troubleshooting
Repairs
(cont.)
5853335
Diagnosis