Diagnosis; Sequence Of Operation And Potential Faults During Each Start-Up Cycle - Viessmann VITODENS 100-W WB1B Series Installation And Service Instructions Manual

Troubleshooting

Diagnosis

Sequence of operation and potential faults during each start-up cycle

Call for heat by control (boiler water
set-point temperature is 5º C / 9º F
above current boiler water
temperature).
yes
6
Water flow switch activates plug 33.
yes
6
Blower starts up.
yes
6
Ignition.
yes
6
Gas combination valve opens.
yes
6
Ionization current builds up / flame
established (symbol A appears).
yes
6
Burner is operating.
64
Display message
Fault F9 after
no
approximately
4
51 seconds.
Fault F4
no
4
Fault F4
no
4
Fault F4
no
4
Burner shuts off when
the boiler temperature is
below the selected boiler
set-point temperature
and immediately starts
up again(cycles).
Corrective action
Increase boiler water set-point
temperature and ensure that there is
4
heat demand.
Check water flow switch. Replace if
necessary (min.flow 400 L/h -
4
1.8 USG/M).
Check boiler pump operation.
Check cabling and plug-in connectors
of the blower, as well as the blower
4
itself. Check proper power supply to
the blower.
Check ignition transformer unit and
its plug-in connections.
4
Check gas combination valve
104VRAC (DC) between brown and
4
blue must be present during start-up,
(plug 35). Check gas supply pressure.
Check electrode settings, purge gas
supply line. Check condensate line
4
and flue gas system for leaks.
Check ignition cable resistance
(4.5K to 5K Ohms).
Check flue gas system for leakage
(flue gas recirculation), check
4
running gas pressure.