4.1 D.H.W. PRODUCTION
The preparation of hot water is guaranteed
by the tank unit in glass enamelled steel
with magnesium anode for the protection of
the tank unit and inspection flange for its
control and cleaning.
The magnesium anode must be checked
annually and substituted when it is worn.
If the boiler does not produce hot water,
make sure that the air has been released
by pressing on the manual outlets after
having switched off the main switch.
4.2 GAS VALVE
The boiler is produced with gas valve model
SIT 845 SIGMA (fig. 26) and gas valve
model HONEYWELL VK 4105M (fig. 27).
The gas valve is set at two pressure values:
maximum and minimum, that correspond,
according to the type of gas, to the values
indicated in Table 4.
The setting of the gas pressure at minimum
and maximum values is carried out by SIME:
variations are discouraged. Only in the pas-
sing from one type of gas supply (methane)
to another (propane) is a change in the
working pressure allowed.
Such an operation must be carried out by
authorised personnel, or the guarantee
will lose validity. Once the change in
working pressure has been carried out,
seal the regulators.
When the gas pressures are to be reset,
this must be done following a set order
first
setting the MAXIMUM and then the MINI-
MUM.
4.2.1 Maximum and minimum
pressure adjustment
SIT 845 SIGMA (fig. 29):
In order to carry out the setting of the maxi-
mum pressure proceed in the following way:
– Connect the manometer to the down-
stream pressure plug of the gas valve.
In the “BF” versions, instead, connect
the manometer as shown in fig. 28.
–
Remove the plastic cap of the modulator (1).
– Place the heating potentiometer knob on
the maximum value.
– Start the boiler by pressing on the four
way switch and the hot water cock.
– Using a ø 10 wrench turn the nut (3) to
find the maximum pressure as shown in
Table 4: to reduce the pressure turn the
nut anti-clockwise, to increase the pres-
sure turn the nut clockwise.
– Turn off and turn on the burner a few
times whilst keeping the hot water tap
constantly open to verify that the pressu-
re corresponds to the values given in
Table 4.
After having regulated the maximum pres-
sure, proceed with the setting of the mini-
mum pressure:
87
4 USE AND MAINTENANCE
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