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The Technical Assistance Service can convert this boiler to natural gas (G20) or liquid gas (G30, G31).
Carry out the following operations:
A) replace the main burner nozzles;
B) change the modulator voltage
C) new max. and min. calibration of the pressure regulator.
A) Replace the burner injectors
• carefully pull the burner off its seat;
• replace the burner injectors making sure they are fully
tightened to prevent gas leaks. The injector diameters are
specified in table 2.
Replacing the diaphragm nozzle
(for models 240 i and 240 Fi)
• remove the gas inlet hose (1 of Figure 13b);
• replace the diaphragm nozzle mounted on the gas valve
(2);
• put back the gas inlet hose.
B) Change the modulator voltage
set parameter F02 according to the gas used, as descri-
•
bed in section 21.
C) Calibrate the pressure regulator
• connect the positive pressure test point of a differential
(possibly water-operated) manometer to the gas valve
pressure test point (Pb) (Figure 13a). For models 240 i/Fi
use the pressure tap (3) in the gas inlet hose (figure 13b).
Connect, for sealed chamber models only, the negative
pressure test point of the manometer to a "T" fitting in
order to join the boiler adjusting outlet, the gas valve
adjusting outlet (Pc) and the manometer. (The same
measurement can be carried out by connecting the ma-
nometer to the pressure test point (Pb) after removing
the sealed chamber front panel);
If you measure the pressure of burners in a different way
you may obtain an altered result in that the low pressure
created in the sealed chamber by the fan would not be
taken into account.
C1) Adjustment to nominal heat output:
• open the gas cock;
•
press the button
• and set the boiler in winter mode
(section 3.2);
• turn on a hot water tap to reach a minimum 10 l/min flow rate or ensure that maximum heating requirements are set;
• check that boiler feeding dynamic pressure, as measured at the inlet gas valve pressure test point (Pa) (Figure 13) is
correct (30 mbar for butane gas, 37 mbar for propane gas or 20 mbar for natural gas);
• remove the modulator cover;
• adjust the tube brass screw to obtain the pressure settings shown in table 1;
C2) Adjustment to reduced heat output:
• disconnect the modulator feeding cable and unscrew the screw to reach the pressure setting corresponding to reduced
heat output (see table 1);
• connect the cable again;
• fit the modulator cover and seal.
C3) Final checks
• attach the additional plate supplied with the transformer, specifying the type of gas and the calibration performed.
INSTRUCTIONS FOR FITTERS
19. GAS CONVERSION METHODS
SIT valve mod. SIGMA 845
Pc
Pb
Pa
Figure 13a
Figure 13b (models 240 i - 240 Fi)
24
7864176 - en
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