Diagnostics; Function Sequence And Possible Faults - Viessmann Vitodens 100 Series Installation And Service Instructions Manual

Function sequence and possible faults

Control unit is-
sues a heat de-
mand
Yes
Fan starts
Yes
Ignition
Yes
Gas train opens
Yes
Symbol A is
shown on the dis-
play
Display
No
No After approx.
1 min, fault F05
No
Fault F04
No
Fault F04 or F08
No Fault F04

Diagnostics

Measure
Increase set value
and ensure heat is
drawn off
Check the fan, fan
connecting ca-
bles, fan power
supply and fan
control
Check the ignition
module connec-
tion
Check the gas
train (230 V con-
trol voltage), gas
supply pressure
and control unit
Check electrode
adjustment and
gas line for air-
locks.
61