BAXI - 925.200.1
15
GB
HU
CZ
INSTRUCTIONS PERTAINING TO THE INSTALLER
925.492.2
17. FITTING A ROOM THERMOSTAT
To connect the room thermostat to the boiler terminal block, proceed as follows:
• reach the power supply terminal block (fi gure 10);
• connect the room thermostat to the terminals (1) - (2) and remove the jumper.
18. GAS CHANGE MODALITIES
A Qualifi ed 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 fi tted (honeywell or SIT;
see fi gure 11).
Carry out the following operations in the given sequence:
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
specifi ed in table 1.
B) Change the modulator voltage
• setting F02 parameter according to the gas used as de-
scribed 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
” fi tting 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 cre-
ated 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 (fi gure 1) and set the boiler in winter mode
(section 3.2);
• open a hot water tap to reach a minimum 10 l/min fl ow rate
or ensure that maximum heating requirements are set;
• remove the modulator cover;
• adjust the tube brass screw (a) Fig. 12 to obtain the pre-
sure 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
);
Figure 11
SIT valve
mod. SIGMA 845
Honeywell valve
mod. VK 4105 M
1
9
92
2
20
0
5
1
Pc
Pb
Pa
02
6
0
4
0
_
7
0
