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5603 880 - 03
Vitoflex 300-RF Service & Maintenance
Heating System Faults
Fault
No.
Text displayed
Indicator
Possible cause
Check / remedy
01
Excess temperature
(red light at F1, F2,
F3)
Fixed high limit
N21
- Incorrect setting in the
control module
- Defective component (pump
or valve)
- Sudden drop in output to zero.
The feed auger then has to be
emptied. The heat produced
by this can result in excess
temperature. Activate the
function “Dissipate excess
heat”
- Why could the heat not be
dissipated?
- Check the boiler pump and
mixing valve
- Activate the function
“Dissipate excess heat”
- Unscrew the protective cap on
the fixed high limit and press
the reset button (not
possible until the boiler
temperature is less than 158°F
(70°C) and press OK
03-17 Interruption or
short-circuit, sensor
- Sensor . . .
- Damaged sensor connection line
- Indicator defective
Call a qualified electrician
09
Oxygen sensor
(red light at F3)
- Oxygen sensor
in the flue
gas pipe
- Indicator very soiled
- Indicator defective
- Error in the electronics
- Readjust oxygen sensor
- Acknowledge with OK
18
Permanent code
(red light at F3)
- Operating hours
lapsed before the
permanent code
has been entered
- Permanent code has not been
entered
- Call Viessmann
19
Repeat heating up
(red light at F3)
- Exhaust gas
temperature
sensor
- Oxygen sensor
- Fuel too moist
- Oxygen sensor imprecise
- Igniter defective
- The combustion chamber
filling time is too short
- Use suitable, dry fuel
- Readjust oxygen sensor.
- Replace ignition device
- Readjust combustion chamber
- Acknowledge with OK
20
Water level in
extinguishing
Water container
(red light at F3)
- Level float switch
in extinguishing
water container
- Not enough water in the
extinguishing water container
- Fill extinguishing water container
- Acknowledge with OK
25
Light barrier, ember
monitoring system
(red light at F3)
- Light barrier for
ember monitoring
system
- Sight glass soiled;
deposits of ash in the openings
- Defective indicator
- Remove and clean sight glasses
on both sides
- Remove dust and ash deposit
from the openings
- Refer to the section,
“Cleaning”
- Acknowledge with OK
26
Light barrier,
feed auger
(red light at F3)
- Light barrier in
the metering
container for the
feed auger
- Light barrier soiled
- Clogging in the metering
container
- Clean light barrier
- Remove clogging
- Acknowledge with OK
96
Feed auger pipe
too hot
- Temperature
sensor on the
feed auger
- Power failure
- Consequent malfunction
caused by excess temperature
- Light barriers for ember
monitoring system soiled
- Call a qualified electrician
- Check light barriers for embers
- Acknowledge with OK
81-93 BUS error, no
connection to the
(red light at F3)
- Data transmission
line for the bus
connection
- Bus connection interrupted
- Check plug connections
- Replace data transmission line
- Call Viessmann
53-54 Extraction system
… silo door open
(red light at F4)
- Limit switch for
silo door
- Silo door open
- Check and close silo door
- Acknowledge with OK
Troubleshooting
