Viessmann Vitodens 222-F Installation And Service Instructions For Contractors page 90

Troubleshooting
Fault codes
(cont.)
Fault code dis- System characteristics
played
40 Mixer is being closed.
44 Mixer is being closed.
48 Mixer is being closed.
4C Mixer is being closed.
50 No DHW heating
58 No DHW heating
95 Burner blocked.
The burner starts again once
the CO level is below the
CO limit.
96 Burner blocked
A3 Burner blocked
A7 Control mode as per deliv-
ered condition
A8 Burner blocked. Venting pro-
gram starts automatically.
A9 If a heating circuit with mixer
is connected, the burner op-
erates at its lower heating
output.
If only one heating circuit
without mixer is connected,
the burner is blocked.
B0 Burner blocked
90
Cause
Short circuit, flow temper-
ature sensor, heating cir-
cuit 2 (with mixer)
Short circuit, flow temper-
ature sensor, heating cir-
cuit 3 (with mixer)
Lead break, flow tempera-
ture sensor, heating circuit
2 (with mixer)
Lead break, flow tempera-
ture sensor, heating circuit
3 (with mixer)
Short circuit, cylinder tem-
perature sensor
Lead break, cylinder tem-
perature sensor
CO limit exceeded
CO limiter sensor fault
Flue gas temperature sen-
sor incorrectly positioned.
No flame formation during
the sensor test
Programming unit faulty
Air in the internal circula-
tion pump or minimum
flow rate not achieved
Internal circulation pump
blocked
Short circuit, flue gas tem-
perature sensor
Measures
Check flow temperature sensor
(see page 102)
Check flow temperature sensor
(see page 102)
Check flow temperature sensor
(see page 102)
Check flow temperature sensor
(see page 102)
Check cylinder temperature sensor
(see page 98)
Check cylinder temperature sensor
(see page 98)
Danger
An increased concentration
of carbon monoxide can
cause potentially fatal car-
bon monoxide poisoning.
Observe the safety instruc-
tions at the beginning of this
manual.
Determine the cause of the in-
creased CO level. Remedy the
fault.
Press Test on the CO limiter.
The alarm is switched off.
Replace the CO limiter.
If the system is to be temporarily
operated without CO limiter, set
parameter 49:0.
Fit flue gas temperature sensor
correctly.
Repeat the test several times if
necessary.
Replace the programming unit.
Vent the system if the fault mes-
sage continues to be displayed.
Check circulation pump.
Check flue gas temperature sensor
(see page 99).