Viessmann Vitovalor 300-P Installation And Service Instructions For Contractors page 117

Fault codes for gas condensing module
Fault code dis- System characteristics
played
7F Circulation pump for dis-
charging buffer stopped
80 Circulation pump for dis-
charging buffer stopped
81 Circulation pump for dis-
charging buffer stopped
A2 Emergency mode with insuffi-
cient system pressure
A3 Burner blocked
A4 Control mode
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
b1 Control mode as per deliv-
ered condition
b4 Regulates as if the outside
temperature were 0 °C.
b5 Control mode as per deliv-
ered condition
b7 Burner blocked
b8 Burner blocked
bA Mixer regulates to 20 °C flow
temperature.
bb Mixer regulates to 20 °C flow
temperature.
(cont.)
Cause
Lead break on top buffer
temperature sensor A
)
Short circuit on bottom
buffer temperature sen-
sor B
)
Lead break on bottom buf-
fer temperature sen-
sor B
)
System pressure too low
Flue gas temperature sen-
sor incorrectly positioned
Max. system pressure ex-
ceeded
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
Communication error, pro-
gramming unit
Internal fault
Internal fault
Coding card fault
Lead break, flue gas tem-
perature sensor
Communication error, mix-
er extension kit for heating
circuit 2 (with mixer)
Communication error, mix-
er extension kit for heating
circuit 3 (with mixer)
Troubleshooting
Measures
Check top buffer temperature sen-
sor (see page 130).
Check bottom buffer temperature
sensor (see page 130).
Check bottom buffer temperature
sensor (see page 130).
Top up with water.
Fit flue gas temperature sensor
correctly (see page 131).
Check the system pressure.
Check the function and sizing of
the expansion vessel.
Vent the heating system.
Coding address "0E" is set to "1" to
document the fault. Must be man-
ually reset to "0" after troubleshoot-
ing.
Replace the programming unit.
Vent the system if the fault mes-
sage persists.
Check circulation pump.
Check the flue gas temperature
sensor (see page 131).
Check connections; replace pro-
gramming unit if necessary.
Replace control unit.
Replace control unit.
Plug in or replace the coding card.
Check the flue gas temperature
sensor (see page 131).
Check mixer extension kit connec-
tions and code.
Check mixer extension kit connec-
tions and code.
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