How To Reset Faults - Viessmann Vitodens 100-W WB1B Series Installation And Service Instructions Manual

Troubleshooting
Diagnosis
(continued)
Diagnostics table: Faults with fault display on control unit (continued)
Fault code in System
display window characteristics*
f1 Burner in fault mode
f2 Burner in fault mode
Burner in fault mode
f3
f4 Burner in fault mode
f8 Burner in fault mode
f9 Burner in fault mode
Burner in fault mode
fa
fc Burner blocked
fd Burner blocked
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

76
Cause
1
Maximum flue gas temperature
exceeded
Fixed high limit tripped
Flame signal is already present
at burner start
No flame signal is present
The combination gas valve
closes too late
Blower speed too low at
burner start
Blower not at stand-still
Electrical fan control (control
unit) faulty
Burner control unit fault
Vitodens 100-W, WB1B Installation & Service
Corrective measures
Check the flue gas system.
Reset control.
Check the heating system water level.
Check the circulation pump. Bleed the
system. Check the fixed high limit and
connecting cables. Reset control.
Check the isolation electrode and connecting
cable. Reset control.
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).
Check the gas train. Check both control
paths. Reset control.
Check the blower, check the blower cables
and supply; check the blower control.
Reset control.
Check the blower, blower connecting
cables and blower control. Reset control.
Check fan connecting cable; if required
replace cable or replace control unit. Reset
control.
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.
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).