Viessmann WB2-44 - Page 32

Troubleshooting
32
Diagnosis (continued)
Diagnostics table: Faults with fault display on control unit (continued)
Fault message in display window
Burner fault
indicator (red)
System behavior
FAULT: 70
RS
/WS REMOTE
CONTROL
OFF Operates based on 68 ºF/20 ºC desired daytime
temperature, 58 ºF/14 ºC desired nighttime temperature.
FAULT: 78
RS
/WS REMOTE
CONTROL
OFF Operates based on 68 ºF/20 ºC desired daytime
temperature, 58 ºF/14 ºC desired nighttime temperature.
FAULT: A1
KM-BUS
BURNER
CONTROL UNIT
Flashes Boiler operates in emergency mode
(after approx. 30 min. BUS fault).
C
O
N
T
R
O
L
U
N
I
T
OFF Boiler cools down.
FAULT: A2 OFF ––
FAULT: A5
KM-BUS
MIXING VALVE
OFF ––
FAULT: B1 OFF DIP switches A and B on back of are switched
(e.g. A-A or B-B).
FAULT: B2 OFF Boiler cools down.
FAULT: B3 OFF Setting via service level not possible.
FAULT: B6
BURNER
CONTROL
UNIT DEFECTIVE
OFF Boiler cools down.
FAULT: CC
(204
*1
)
ON Burner control unit switches to lockout
(due to large line voltage fluctuations).
FAULT: C8 OFF Boiler does not activate.
FAULT: C0 OFF Boiler does not activate.
FAULT: E4 or E... OFF ––
FAULT: F2 OFF ––
FAULT: F5 OFF ––
FAULT: F9
(249
*1
)
OFF/ON Burner control switches to lockout.
FAULT: FB Flashes ––
FAULT: FD
(253
*1
)
ON Burner control switches to lockout.
*1
Displayed when fault codes retrieved from fault memory.
5285 961 v1.3