Function Sequence And Possible Faults - Viessmann VITODENS 242-F Installation And Service Instructions Manual

Further details regarding the individual steps
Supply pressure (flow pressure)
For natural gas
Below 17.4 mbar
(1.74 kPa)
17.4 to 25 mbar
(1.74 to 2.5 kPa)
Above 25 mbar
(2.5 kPa)

Function sequence and possible faults

Control unit is-
sues a heat de-
mand
Yes
Fan starts
Yes
Ignition
For LPG
Below 42.5 mbar
(4.25 kPa)
42.5 to 57.5 mbar
(4.25 to 5.75 kPa)
Above 57.5 mbar
(5.75 kPa)
Display
No
No
After approx. 51 s,
fault F9
No Fault EE
Commissioning, inspection, maintenance
(cont.)
Action
Do not start the boiler. Notify your gas
supply utility or LPG supplier.
Start the boiler.
Install a separate gas pressure governor
upstream of the system and regulate the
pre-charge pressure to 20 mbar
(2.0 kPa) for natural gas or 50 mbar
(5.0 kPa) for LPG. Notify your gas supply
utility or LPG supplier.
Action
Increase set value
and ensure heat is
drawn off
Check the fan, fan
connecting cables,
power at the fan
and fan control
Check ignition
module (control
voltage 230 V
across plugs
"X2.1" and "X2.2").
Check the gas sup-
ply.
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