Viessmann Vitopend 100-W - Diagnostics; Function sequence and possible faults

68
Display Measure
Control unit is-
sues a heat de-
mand
No
Increase set value
and ensure heat is
drawn off
Yes
Fan starts
No
After approx. 51 s
fault "F05"
Check the air
pressure switch,
fan, fan connect-
ing cables and fan
power supply
Yes
Ignition
No
Fault "F04" Check the ignition
module connec-
tion
Yes
Gas train opens
No
Fault "F04" Check the gas
train (230 V con-
trol voltage) and
gas supply pres-
sure
Yes
Ionisation current
builds (above
2 µA)
Symbol
A
No
Fault "F04" Check the ionisa-
tion current, check
the electrode ad-
justment and the
gas line for air-
locks.
Diagnostics
Function sequence and possible faults
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