Internal System Faults - Viessmann VITOCROSSAL CRU 800 kW Service Instructions Manual

Troubleshooting
Fault codes
(cont.)
Displayed fault System characteristics
code
F F1 Burner control unit in a fault
state; system cools down.
F F2 Burner control unit in a fault
state; system cools down.
F FB Burner does not start.

Internal system faults

Internal system faults will be shown if the correct pro-
gram sequence can no longer be guaranteed.
Displayed fault System characteristics
code
F E5, F EC, Fault in burner control unit
F ED, F FF area
F FD Fault in burner control unit
area
Detailed error codes for F FD
Detailed er- Component/signal Cause of fault
ror code
30 Reset button
31 Fuel valve 2 feed-
back
32 Air pressure switch
1
34 Gas pressure
switch 1
42
Cause
Flue gas temperature lim-
iter has responded
Flue gas temperature
■
too high
Excessive gas through-
■
put
Boiler water temperature
limiter has responded.
Boiler water temperature
too high.
Combustion chamber
■
pressure too high
(LDW2)
Condensate backed up
■
Flue gas path blocked
■
Flue gas damper does
■
not open or close.
Burner control unit con-
■
figured incorrectly
Cause
Internal system fault and
EMC
See the following table
Programming unit faulty
Wiring
Incorrect return voltage
(e.g. DC voltage)
Actuator faulty
High switching se-
quence, switch flutters
External voltage
High switching se-
quence, switch flutters
External voltage
Measures
Wait until temperature falls below
■
the permissible flue gas tempera-
ture.
Check the system pressure.
■
Check heat exchanger surfaces
■
for soiling.
Reset the burner control unit.
■
Check the CO
■
Adjust gas throughput in accord-
■
ance with the rated boiler heating
output. See "Specification" for
connected values.
Wait until temperature falls below
■
the permissible boiler water tem-
perature.
Reset the burner control unit.
■
Check condensate drain and flue
■
gas path for blockages.
Check flue gas damper.
■
Check motorised flue gas damp-
■
er operating parameters.
Measures
Reset the burner control unit. Re-
place the burner control unit if the
fault persists.
See the following table
Measure
Replace programming unit.
Check wiring.
Remove plug from fuel valve 2, reset burner con-
trol unit and check error messages. If F Fd recurs,
replace burner control unit. Otherwise, replace
fuel valve 2.
Check flue gas path and combustion. Check set-
ting LDW1. Check burner gauze assembly for
soiling.
Check the gas supply. Check setting GDW1 and
gas train intake screen.
setting.
2