Viessmann Vitoflame 300 VHG III Service Instructions Manual page 20

Troubleshooting
Diagnosis
(cont.)
Fault
Excessive flue gas temper-
ature
Burner operates, constant
red flickering light on the
burner control unit
Condensate backup in flue
gas heat exchanger
20
Cause of fault
Excessive oil throughput
Boiler contaminated
Air in flue gas heat exchanger
Flue gas heat exchanger contaminated
Not all consumers are connected to the
flue gas heat exchanger
Pump faulty: Insufficient throughput
through the flue gas heat exchanger
Not a fault; interface diagnosis was acti-
vated accidentally
Siphon or neutralising system contami-
nated
Action
Match oil throughput to rated boiler heat-
ing output
Clean boiler and correct burner settings
Vent flue gas heat exchanger
Clean flue gas heat exchanger
Connect consumers correctly
Replace pump
Press the reset button for
LED illuminates yellow, then release
Clean siphon and neutralising system
3 s until the
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