Viessmann Vitocrossal 300 CA3 2.5 Installation And Service Instructions Manual page 184

Troubleshooting
Burner Fault Codes
Displayed System characteristics
fault code
F1 Burner control unit in a fault
state; system cools down.
F2 Burner control unit in a fault
state; system cools down.
F3 Ionization flame monitor reports
faulty flame signal during start-
up or after the post-purge.
F4 No flame formation during safety
time; ionization flame monitor
reports no flame signal.
No flame formation during safety
time; ionization flame monitor
reports no flame signal.
No flame formation during safety
time; ionization flame monitor
reports no flame signal.
Poor start-up characteristics;
rotary damper does not close.
Flame does not build during the
safety time, no signal captured
by the ionization flame monitor.
Flame does not build during the
safety time, no signal captured
by the ionization flame monitor.
Flame does not build during the
safety time, no signal captured
by the ionization flame monitor.
184
(continued)
Cause
Secondary boiler water
temperature sensor exceeded
Excessive boiler water
temperature.
Gas valve not gas tight (gas is
escaping and burning);
incorrect coding card.
Ionization electrode incorrectly
adjusted; ionization electrode not
plugged in. Ground leakage of
electrode or cable.
Ignition electrodes incorrectly
adjusted, electrodes grounded,
faulty ignition unit, faulty burner
control unit.
Insulation body of ignition or
ionization electrode cracked.
Servomotor faulty, servomotor
connecting cable faulty, output
relay faulty (burner control unit).
Incorrect gas type selected.
Gas valve does not open.
Combustion characteristics not
ideal.
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Measures
Wait until temperature falls
below the permissible boiler
water temperature. Reset burner
control unit. Verify boiler flow air
pockets.
Wait until temperature falls
below the permissible boiler
water temperature.
Reset burner control unit.
Check ionization path; replace
coding card; replace gas valve.
Insert plug of ionization
electrode; check cables; adjust
ionization electrode (see boiler
service instructions)
Adjust ignition electrodes (see
boiler service instructions);
replace ignition unit; replace
burner control unit.
Replace ignition or ionization
electrode
Replace connecting cable;
replace servomotor; replace
burner control unit.
Select gas type (see boiler
service instructions).
Check connecting cable; check
gas valve and replace if required.
Adjust the burner (see boiler
service instructions); if
necessary also adjust the setting
screws when the burner is off to
be able to start the burner).