How To Reset Faults - Viessmann VITODENS 100-W Installation And Service Instructions Manual

Troubleshooting
Diagnosis
(continued)
Diagnostics table: Faults with fault display on control unit (continued)
Fault System behavior
message
in display
window
f4
Burner in fault mode
f8
Burner in fault mode
f9
Burner in fault mode
fa
Burner in fault mode
fc
Burner blocked
fd
Burner blocked
ff
Burner blocked
*1
Constant mode: Boiler operates based on "
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

tr
Fig. 66
66
*1
Cause
No flame signal is present.
Combination gas valve closes too
late.
Blower speed too low at burner
start.
Blower not at stand-still (blower
must be in stand-still when in stand-
by mode).
Electrical fan control (control unit)
faulty.
Burner control unit fault.
Burner control unit fault.
tr r r r
" temperature setting
Turn rotary selector "tr
seconds to "U U U 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).
Corrective measures
Check the ionization electrode and
leads, check the gas pressure, check
the gas combination valve, control
unit and condensate drain.
Reset control.
Check the gas train. Check both air
and gas flow paths. Reset control.
Check the blower, check the blower
cables and supply, check the blower
control. Reset control.
Check the blower, check the blower
cables, check the blower control.
Reset control.
Check fan connecting cable; if re-
quired, replace cable or replace con-
trol unit. Reset control.
Check ignition electrodes and
connecting cables. Check whether a
strong inference (EMC) field near the
equipment. Correct if applicable.
Replace control unit if the fault
persists. Reset control.
Check ignition electrodes and
connecting cables. Check whether a
strong inference (EMC) field near the
equipment. Correct if applicable.
Replace control unit if the fault
persists. Reset control.
r r " less than 2 r