Viessmann Vitoligno 250-S Installation And Service Instructions For Contractors page 51

Fault display
Faults are signalled on the display by means of a
"Fault" message and by an illuminated red fault indi-
cator.
Checking and acknowledging faults
Note
If an acknowledged fault is not remedied, the fault
message is re-displayed the following day:
Press the following keys:
1. for troubleshooting.
d
Calling up acknowledged fault messages
Press the following keys:
1. + Simultaneously for approx. 4 s.
The "Service" menu appears.
2. / For "Fault history".
| ~
Plain text fault display
The following faults are displayed as plain text. The
meaning of the fault and the fault code shown to the
right are detailed in the table on page 52.
■ "Excess temperature"
"Repeat heat-up"
■
"Fault O2 probe"
■
–
"Boiler flow"
■
■ "Boiler return"
■ "Flue gas sensor"
Calling up fault codes from the fault memory (fault history)
The 10 most recent faults are saved and can be called
up.
Faults are sorted by date. The most recent fault is
given the fault number 1.
Fault
Outside temp sensor
Fault O2 probe
Acknowledge with OK
Fig. 31
34
91
2. / To select the fault message to be acknowl-
| ~
edged, if several faults are present.
3. For "Acknowledge".
d
4. / for "Yes" or "No".
| ~
5. To confirm.
d
3. To confirm.
d
4. / For "Display?".
| ~
5. To confirm.
d
6. / For the list of current faults.
| ~
■ "Outside sensor"
■ "Buffer sensor, top"
■ "Buffer sensor, centre"
■ "Buffer sensor, bottom"
"Flow sensor"
■
"DHW sensor"
■
"Return sensor"
■
■ "KM BUS"
Press the following keys:
1. + Simultaneously for approx. 4 s.
The "Service" menu appears.
2. / For "Fault history".
| ~
3. To confirm.
d
4. / For "Display?".
| ~
5. repeatedly, until the standard display
ä
is shown.
Troubleshooting
51