4
USE AND MAINTENANCE
4. 1
GAS VALVE (fig. 18)
The boilers are equipped standard with the
SIT 845 SIMGA / HONEYWELL VK 4105M
/ SIEMENS VGU 56 gas valve (fig. 18).
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 4. The gas pressures
at the maximum and minimum values, are
factory set. Consequently 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.
4.2
GAS CONVERSION (fig. 19)
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. 19):
– Close the gas cock.
– Disassemble the burner manifold (3).
– Replace the main nozzles (6) supplied in
a kit, inserting the copper washer (4).
Use a ø 7 spanner to perform this ope-
ration.
– Configure the new fuel as indicated in
point 4.2. 1
– For calibrating the maximum and mini-
mum gas pressure values, see point
4.2.2.
– 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: When reassembling components
which you have removed, replace gas
seals; test all gas connections after
assembly using soapy water or a product
made specifically for the purpose, being
sure not to use open flame.
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 bur-
ner units for which it is not specified.
5
4
1
3
KEY
6
1
Modulator
2
EV1-EV2 coils
3
Pressure inlet upstream
4
Pressure inlet downstream
5
VENT pressure test point
TABLE 4
Model
Burner max pressure mbar
G20 (*) G30
25 OF
11.0
30 OF
11. 1
25 BF
11.8
30 BF
12.0
35 BF
13.7
20 BFT
11.0
25 BFT
11.8
(*) Max. burner pressure is guaranteed only when the supply pressure exceeds the max. burner pressure by at least 3 mbar.
4.2. 1
New fuel configuration
For access to the installer's parameters,
press simultaneously keys
5 seconds (3 fig. 14).
The parameters will scroll up and down
with the keys
The display pane will show the values of the
parameter PAR 1. If, for example, the boiler
in question is a "25 BF" fuelled by methane,
the following setting SET 2 will appear:
To change the fuel to LPG, it is necessary to
set SET 6, by pressing the key
Fig. 19
SIT 845 SIGMA
2
Modulator current mA
G31
G20 (*) G30
G31
27.7
35.7
130
165
165
27.7
35.7
130
165
165
28.5
36.5
130
165
165
28.5
36.5
130
165
165
28.2
36.2
130
165
165
28.5
36.5
130
165
165
28.5
36.5
130
165
165
and
for
and
.
.
HONEYWELL VK 4105M
3
4
5
2
1
SIEMENS VGU 56
2
3
4
5
Burner min pressure mbar Modulator current mA
G20 (*) G30
G31
G20 (*) G30
1.8
4.7
4.7
0
0
1.9
4.8
4.8
0
0
2.0
4.8
4.8
0
0
2. 1
5.0
5.0
0
0
2.2
4.5
4.5
0
0
1.9
4.8
4.8
0
0
2.0
4.8
4.8
0
0
The standard display will automatically
return after 10 seconds.
The table below shows the SET settings to
enter when the type of gas fuel is changed.
BOILER
GAS
MODELS
METHANE
20
25
30
BF/BFT
35
LPG
20
25
30
35
METHANE
25
OF
30
LPG
25
30
4.2.2
Adjusting valve pressure (fig. 20)
Set maximum and minimum pressure on
gas valves as follows (fig. 20):
ES
PT
ENG
1
G31
0
0
0
0
0
0
0
Fig. 18
PAR 1
1
2
3
4
5
6
7
8
9
10
11
12
107