Viessmann B1HF Installation And Service Instructions Manual page 81

Fault messages
(cont.)
Displayed fault System characteristics
code
540 Burner in a fault state
544 Emergency function operat-
ing mode is activated for
heating circuit 2:
Mixer closes. Heating circuit
pump is operational.
545 Emergency function operat-
ing mode is activated for
heating circuit 2:
Mixer closes. Heating circuit
pump is operational.
574 Room temperature sensor for
heating circuit 1 not available
738 Normal operation
Cause
Condensate backup in the
heat cell
Lead break, flow tempera-
ture sensor, heating circuit
2 with mixer
Incorrect setting during
commissioning
Short circuit, flow temper-
ature sensor for heating
circuit 2 with mixer
Normal operation without
room influence
OpenTherm remote con-
trol unit connected but not
configured
Troubleshooting
Measures
Check system for condensate
■
backup.
Check the condensate drain and
■
trap.
Replace insulation blocks, elec-
■
trodes and burner gauze assem-
bly if required.
Note
To prevent water damage, detach
fan unit before removing the burn-
er.
Reset the appliance.
Check flow temperature sensor,
mixer 2.
Measure voltage at sensor input on
electronics module. Set value:
3.3 V with sensor disconnected.
–
Check setting in the commission-
ing assistant and correct if re-
quired.
Checking setting of ADIO rotary
switch.
Check flow temperature sensor,
mixer 2.
Measure voltage at sensor input on
electronics module. Set value:
3.3 V with sensor disconnected
–
Check external room temperature
sensor in heating circuit or room
temperature sensor on remote
control unit
Set C.7 in the commissioning as-
sistant to a value of 14.
81