Gas Conversion - Baxi Nuvola 3+ BS40 Operating And Installation Instructions

The authorised Technical Assistance Service can convert this boiler to natural gas (G. 20) or liquid gas (G. 30, G. 31).
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 to fully tighten
them to prevent gas leaks. Injector diameters are specified
in table 2.
Replacing the diaphragm nozzle
• remove the gas inlet hose (1 of Figure 8b);
• 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 19.
C) Calibrate the pressure regulator
• connect the positive pressure test point of a differential
pressure gauge (possibly water-operated) to the gas valve
pressure test point (Pb) (Figure 8a). For models 240 i use
the pressure tap (3) in the gas inlet hose (figure 8b).
C1) Adjustment to nominal heat output:
• open the gas cock;
• press the button (and set the boiler in winter mode
(section 3.2);
• open a hot water tap that can provide a flow rate of at
least 10 litres a minute or make sure there is maximum
heat demand;
• check that the boiler feeding dynamic pressure, as
measured at the inlet gas valve pressure test point (Pa)
(Figure 8a) is correct (30 mbar for butane gas, 37 mbar
for propane gas or 20 mbar for methane 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);
• reconnect the cable;
• 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

17. GAS CONVERSION

Figure 8a
Figure 8b
40
Valve SIT
mod. SIGMA 845
Pc
Pb
Pa
7217402.01 - en