86
This connection should also be used to test
the minimum and maximum gas pressure
values. To correct the calibration, if requi-
red, follow the instructions in paragraph
4.5.1.
4.3 GAS VALVE
The “FORMAT” boilers, are equipped stan-
dard with the SIT 837 TANDEM gas valve (fig.
28) and with HONEYWELL VK 4105M gas
valve (fig. 28/a).
The gas valve is set at two pressure values:
maximum and minimum.
According to the type of gas burnt, these
correspond to the values given in Table 5.
The gas pressures at the maximum and
minimum values, are factory set. Conse-
quently they must not be altered.
Only when you switch the appliance from
one type of gas supply (methane) to
another (butane or propane), it is permit-
ted to alter the operating pressure.
4.5 GAS CONVERSION
This operation must be performed by
authorised personnel using original Sime
components.
To convert from natural gas to LPG or vice
versa, perform the following operations (fig.
29):
– Close the gas cock.
– Remove the burner assembly.
– Replace the main nozzles (6) supplied in
a kit, inserting the copper washer (4).
Use a 7 spanner to perform this opera-
tion.
–
Remove the “METANO/GPL” connector
link on the card and set it in the posi-
tion corresponding to the gas to be
used (4 fig. 21).
– To set the values of maximum and mini-
mum gas pressure, follow the instruc-
tions given in section 4.5.1.
– After have ultimated the conversion of
the boiler, please stick onto the casing
panel the plate showing the relevant fee-
ding gas which is included into the kit.
NOTE: after assembly, all gas connections
should be tested with a sealing test using
soapy water or special products and spe-
cifically avoiding the use of free flames.
Conversion operations should be perfor-
med by skilled personnel only.
4.5.1
Adjusting valve pressure
Set maximum and minimum pressure on
gas valves as follows (fig. 30):
– Connect the column or a manometer to
the intake downstream of the gas valve.
–
Disconnect the valve VENT pressure test
point tube
(5 figg. 28-28/a).
– Remove the cap (1) from the modulator.
– Place the hot tap water potentiometer
knob at the maximum position.
KEY
1 Modulator
2 EV1 - EV2 coils
3 Pressure inlet upstream
4 Pressure inlet downstream
5 VENT pressure test point
Fig. 28/a
Fig. 28
KEY
1 Modulator
2 EV1 - EV2 coils
3 Pressure inlet downstream
4 Pressure inlet upstream
5 VENT pressure test point
TABLE 5
Burner max. Modulator Burner min. Modulator
Type of gas pressure
(mbar)
current pressure
(mbar)
current
25 OF C 30 OF C 25 BF TS 30 BF TS mA 25 OF C 30 OF C 25 BF TS 30 BF TS mA
Methane
- G20 9.7 10.5 12 12.5 130 1.9 2.1 2.1 2.4 0
Butane
- G30 27.5 27.5 28.2 28.1 165 5 5.2 4.7 4.9 0
Propane
- G31 35.5 35.5 36.2 36.1 165 5 5.2 4.7 4.9 0
Fig. 28/b
SEALED CHAMBER
MANOMETER
VENT PLUG
PRESSURE INLET UPSTREAM
Fig. 29
KEY
1 Swivel connection 1/2”
2 Locknut 1/2”
3 Burner manifold
4 Washer ø 6,1
5 Burners
6 Nozzle M6
7 Screw
WARNING: To ensure a perfect seal,
always use the washer (4) supplied in the
kit when replacing nozzles, even in burner
units for which it is not specified.
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