Viessmann B1HF Installation And Service Instructions Manual page 68

Troubleshooting
Fault messages
(cont.)
Displayed fault System characteristics
code
29 Regulates without flow tem-
perature sensor for low loss
header.
30 Regulates without flow tem-
perature sensor for low loss
header.
49 Burner in a fault state
50 Burner in a fault state
57 Control mode without room
influence
58 Control mode without room
influence
59 Burner blocked, boiler circuit
pump off. No central heating,
no DHW heating
62 Burner in a fault state
68
Cause
Lead break, low loss
header sensor
Short circuit, low loss
header sensor
Lead break, flue gas tem-
perature sensor
Short circuit, flue gas tem-
perature sensor
Lead break, room temper-
ature sensor
Short circuit, room tem-
perature sensor
Power supply, low voltage
High limit safety cut-out
has responded.
Measures
Check commissioning assistant
■
setting, low loss header.
Check flow temperature sensor,
■
low loss header.
Measure voltage at sensor input
■
on electronics module. Set value:
3.3 V with sensor disconnected
–
Check flow temperature sensor,
low loss header.
Measure voltage at sensor input on
electronics module. Set value:
3.3 V with sensor disconnected
–
Check flue gas temperature sen-
sor.
Reset the appliance.
Check flue gas temperature sen-
sor.
Reset the appliance.
Check commissioning setting of
■
remote control.
Check plug and cable of external
■
room temperature sensor, heat-
ing circuit.
If no external room temperature
■
sensor installed, replace Vitotrol
programming unit.
Check plug and cable of external
room temperature sensor, heating
circuit.
If no external room temperature
sensor installed, replace Vitotrol
programming unit.
Check mains voltage.
If voltage is correct and the fault
occurs repeatedly, replace the fan
unit.
Check heating system fill level.
■
Check pre-charge pressure in di-
■
aphragm expansion vessel. Ad-
just to required system pressure.
Check whether flow rate is suffi-
■
cient (circulation pump).
Check function of 3-way diverter
■
valve. Vent the system.
Reset the appliance.