37
Supply pressure (flow pressure)
Measures
For natural gas
< 20 mbar (2.0 kPa)
Do not start the boiler. Notify the gas supply utility.
20 - 25 mbar (2.0 - 2.5 kPa)
Start the boiler.
> 25 mbar (2.5 kPa)
Install a separate gas pressure governor upstream of the system. Set the
pre-charge pressure to 20 mbar (2.0 kPa) for natural gas. Notify the gas
supply utility.
Function sequence and possible faults
Display
Measure
Control unit issues a heat
demand
No
Increase set value. Ensure
heat transfer.
Yes
Fan starts
No
Fault 59, 457
Check the fan connecting ca-
bles. Check the fan power
supply.
Yes
Ignition
No
Fault 359
Check ignition module (con-
trol voltage 230 V across
plug "X1/54" terminals "L"
and "N" on the HBMU).
Check the gas supply.
Yes
Gas solenoid valve opens
No
Fault 357
Check the gas supply pres-
sure.
Yes
Ionisation current builds
No
Fault 369, 380
Check distance of ionisation
electrode on burner gauze
assembly.
Purge the gas line.
Yes
Burner in operation
No
Shuts down below the set
boiler water temperature and
restarts immediately.
Check the flue system for
tightness (flue gas recircula-
tion). Check gas flow pres-
sure.
Commissioning, inspection, maintenance
Checking the static pressure and supply pressure
(cont.)
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