49
925.224.3 - EN
INSTRUCTIONS PERTAINING TO THE INSTALLER
A Qualified Service Engineer may adapt this boiler to operate with natural gas (
G. 20
) or with liquid gas (
G. 31
).
The procedure for calibrating the pressure regulator may vary according to the type of gas valve fitted (HONEY WELL or
SIT; see figure 11).
Carry out the following ope rations in the given sequence:
A) substitute the main burner injectors;
B) change the modulator voltage;
C) proceed with a new max. and min. setting of the pressure adjusting device.
A) Substitute the main burner injectors
• carefully pull the main burner off its seat;
• substitute the main burner injectors and make sure you tighten them to avoid leakage. The nozzle diameters are spe
-
cified in table 1.
B) Change the modulator voltage
• setting
F02
parameter according to the gas used as described in section 20.
C) Pressure adjusting device setting
• connect the positive pressure test point of a differential (possibly water-operated) manometer to the gas valve pressure
test point (
Pb
) (Figure 11); 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 manometer 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 tap;
• press
button (figure 1) and set the boiler in winter mode (section 3.2);
• open a hot water tap to reach a minimum 10 l/min flow rate or ensure that maximum heating requirements are set;
• remove the modulator cover;
• adjust the tube brass screw (a) Fig. 12 to obtain the pressure settings shown in table 1;
• check that boiler feeding dynamic pressure, as measured at the inlet gas valve pressure test point (
Pa
) (Figure 11) is
correct (37 mbar for propane gas
G.31
,
20 mbar
for natural gas
G20
);
18. GAS CHANGE MODALITIES
17. FITTING A ROOM THERMOSTAT
To connect the room thermostat to the boiler terminal block, proceed as follows:
• reach the power supply terminal block (figure 10);
• connect the room thermostat to the terminals (1) - (2) and remove the jumper.
Figure 11
SIT valve mod. SIGMA 845
Honeywell valve mod. VK 4105 M
0904_0701
