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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 8).
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 19.
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 8).
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. 8 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 8) is
correct (37 mbar for propane gas
G.31
,
20 mbar
for natural gas
G20
);
17. GAS CHANGE MODALITIES
16. FITTING A ROOM THERMOSTAT
To connect the room thermostat to the boiler terminal block, proceed as follows:
• reach the power supply terminal block (figure 7);
• connect the room thermostat to the terminals (1) - (2) and remove the jumper.
Figure 8
SIT valve mod. SIGMA 845
Honeywell valve mod. VK 4105 M
0904_0701
