Function Sequence And Possible Faults (Gas Condensing Module) - Viessmann Vitovalor PT2 Installation And Service Instructions For Contractors

Measuring connection pressure (flow pressure)
Supply pressure (flow pressure)
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 (gas condensing module)

Control unit issues a heat
demand
Yes
Fan starts
Yes
Ignition
Yes
Gas train opens
Yes
Ionisation current builds
Yes
Burner in operation
Measures
Do not commission the appliance. Notify the gas supply utility.
Start up the appliance.
Connect the separate gas pressure governor upstream of the system and
set the pre-charge pressure to 20 mbar (2.0 kPa). Notify the gas supply
utility.
Display
No
No Fault F.59, F.457
No Fault F.359
No
Fault F.357
No Fault F.369, F.380
No Shuts down below the set
boiler water temperature and
restarts immediately.
Commissioning, inspection, maintenance
(cont.)
Measure
Increase set value. Ensure
heat transfer.
Check connection cables on
fan. Check power supply on
fan.
Check ignition module (con-
trol voltage 230 V across
plugs "X18.1" and "X18.3" on
the burner control units).
Check the gas supply.
Check the gas supply pres-
sure.
Check distance of ionisation
electrode on burner gauze
assembly.
Purge the gas line.
Check the flue system for
tightness (flue gas recircula-
tion). Check gas flow pres-
sure.
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