76
5600 332 v1.3
Vitodens 100-W, WB1B Installation & Service
Troubleshooting
Diagnosis
(continued)
Diagnostics table: Faults with fault display on control unit
(continued)
Fault code in
display window
System
characteristics
*
1
Cause
Corrective measures
f1
Burner in fault mode
Maximum flue gas temperature
exceeded
Check the flue gas system.
Reset control.
f2
Burner in fault mode
Fixed high limit tripped
Check the heating system water level.
Check the circulation pump. Bleed the
system. Check the fixed high limit and
connecting cables. Reset control.
f3
Burner in fault mode
Flame signal is already present
at burner start
Check the isolation electrode and connecting
cable. Reset control.
f4
Burner in fault mode
No flame signal is present
Check ignition electrodes and wires.
Measure the ionization current, check
the gas pressure, check the gas train,
ignition, ignition module and condensate
drain. Reset control. Check ignition cable
resistance (4.5K to 5K ohms).
f8
Burner in fault mode
The combination gas valve
closes too late
Check the gas train. Check both control
paths. Reset control.
f9
Burner in fault mode
Blower speed too low at
burner start
Check the blower, check the blower cables
and supply; check the blower control.
Reset control.
fa
Burner in fault mode
Blower not at stand-still
Check the blower, blower connecting
cables and blower control. Reset control.
fc
Burner blocked
Electrical fan control (control
unit) faulty
Check fan connecting cable; if required
replace cable or replace control unit. Reset
control.
fd
Burner blocked
Burner control unit fault
Check ignition electrodes and connecting
cables. Check whether a strong
interference (EMC) field exists near the
equipment (correct if applicable). Reset
control. Replace control unit if the fault
persists.
*
1
Constant mode: Boiler operates based on
“
tr
”
temperature setting
Burner blocked: If fault cause is corrected, burner resumes operation.
Burner in fault mode: Boiler control requires manual reset before burner can resume operation.
How to reset faults
Turn rotary selector “
tr
” less than 2 seconds to “
U
Reset
”, then back to the control range.
This operation will put the boiler in relay test mode if
no fault is present (turn boiler off then back on to start
again).