Troubleshooting; Function Sequence And Possible Faults - Viessmann VITODENS 100-W Installation And Service Instructions Manual

Function sequence and possible faults

Control unit issues
a heat demand
Yes
Fan starts
Yes
Ignition
Yes
Gas train opens
Display
No
No No fault display
After approx. 51 s
fault F9
No Fault F4
No
Fault F4

Troubleshooting

Action
Increase set value
and ensure heat is
drawn off
Heating water flow
rate too low. In-
crease flow rate
and ensure heat is
drawn off.
Check flow sensor
and connecting ca-
ble.
Check the fan, fan
connecting cables,
power at the fan
and fan control
Check the ignition
module connec-
tion
Check the gas
train (control volt-
age 230 V); check
the gas supply
pressure
31