Gas Conversion; Gas Valve - De Dietrich MS 24 BIC FF Manual Para El Usuario

The authorised Technical Assistance Service can convert this boiler to natural gas (G. 20) or liquid gas (G.31).
Carry out the following operations:
A) replace the nozzles of the main burner and the gas diaphragm (if fitted);
B) new max. and min. calibration of the pressure regulator.
A) Replace the burner nozzles
• carefully pull the main burner off its seat;
• replace the main burner nozzles making sure to fully tighten them to prevent gas leaks. Nozzle diameters are specified
in table 2.
• replace the gas membrane located on the gas valve (figure 10). The diameter of the membrane is specified in table 2.
Attention: it is not necessary to change parameter F02.
B) 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 10). Only for models with sealed chambers, connect the negative pressure test point of
the manometer to a "T" fitting in order to join the boiler adjustment outlet, the gas valve adjusting outlet (Pc) and the
pressure gauge. (The same measurement can be made by connecting the pressure gauge to the pressure test point
(Pb) after removing the front panel of the sealed chamber);
Measuring burner pressure using methods other than those described could lead to incorrect results as the low pressure
created by the fan in the sealed chamber would not be taken into account.
B1) Adjustment to nominal heat output:
• open the gas tap and switch the boiler to the Winter mode;
• take the boiler to maximum power as described in section 19.1;
• remove the modulator cover;
• adjust the tube brass screw (a) until the pressure values shown in table 1 are obtained;
• make sure that the dynamic inlet pressure of the boiler, measured at the gas valve pressure test point (Pa) (Figure 10)
is correct (37 mbar for propane or 20 mbar for natural gas).
B2) Adjustment to reduced heat output:
• disconnect the modulator power cable and unscrew the screw (b) until a pressure value corresponding to reduced heat
output is achieved (see tab. 1);
• reconnect the cable;
• mount the modulator cover and seal.
B3) Final checks
• attach the additional plate supplied with the transformer, specifying the type of gas and the calibration performed.

gas valve

mod. SIGMA 845
Figure 10
ATTENTION
If the natural gas inlet pressure is too low (less than 17 mbar) remove the gas diaphragm installed over the gas valve (fig.
10) and set parameter F02=00 on the electronic board (§21).
INSTALLATION INSTRUCTIONS

19. GAS CONVERSION

gas diaphragm
a
b
73
Figure 11
71.06199.02 - EN