4. Checking the setting of the gas pressure sensitive switch(es)
20 mbar versions
The minimum gas pressure switch fitted on the safe-
ty valve is factory-set to a value of 12.5 mbar, this
corresponds to natural gas setting.
300 mbar versions
The gas train of the 300 mbar DTG 320 S boiler is fit-
ted with two gas pressure switches: a minimum pres-
sure switch I set to 150 mbar and a maximum pres-
sure switch J set to 50 mbar.
- the minimum pressure switch I monitors the
upstream pressure (supply pressure).
It is adjusted in order to turn the boiler off as soon as
the supply pressure reaches a minimum value that
cannot be used by the burner (factory presetting: 150
mbar).
The maximum pressure switch J monitors the down-
stream pressure (injection nozzles pressure).
It is adjusted in order to turn the boiler off as soon as
an excessive pressure appears (factory presetting:
50 mbar).
These pressure switches are mounted on the 300
mbar multiblock gas valve and are connected electri-
cally in series.
Note: the maximum gas pressure switch J must be
reset manually. If the manifold pressure exceeds the
required value of 50 mbar (abnormal supply network
pressure increase, break of a gas reducing valve, ...),
the maximum pressure switch interrupts the electrical
power supply of the safety control box and locks
itself. Restarting the boiler will only be possible man-
ually, after resetting the maximum pressure switch
(reset button K on the pressure switch front side).
I
Minimum pressure switch
J Maximum pressure switch
K Maximum pressure switch reset button
5. Fixing the label
Fix the laber which indicates the type of gas for which
the boiler is fitted and set
For operating with propane, set the start pressure to
20 mbar.
If the gas supply pressure drops, the minimum pres-
sure switch turns the boiler off.
J
27
I
J
K
8358N012
GB