4.1
TEMPERATURE
ADJUSTMENT OF D.H.W.
The sistem with a potentiometer for adju-
sting the temperature of D.H.W. with a set-
ting range from 40° to 60°C offers a dou-
ble advantage:
1) The boiler adapts perfectly to any type of
D.H.W. system, whether the mixing
system is a mechanical or a thermostat-
controlled type.
2) The thermal output is dosed according
to the temperature required, which
means a considerable saving in fuel.
NOTE: In order to avoid any misunder-
standing please remember that the value
obtained by the product of temperature
difference (in °C) between D.H.W. output
and input into the boiler by the hourly
flow rate measured on the tap, where
hot water is drawn off (l/h), cannot be
higher than the useful output developed
by the boiler. For measurements and
checks on flow rate and temperature of
D.H.W., use suitable instruments, taking
into consideration any heat dispersion
along the stretch of piping between the
boiler and the measuring point.
4.2
ADJUSTMENT OF
D.H.W. FLOW RATE
To adjust the hot water flow rate, use the
flow-rate regulator on the pressure switch
valve (5 fig. 7). Remember that the flow
rates and corresponding temperatures of
use of hot water, given in section 1.3, have
been obtained by positioning the selector of
the circulation pump on the maximum value.
Should there be any reduction in the
D.H.W. flow rate, the filter installed on the
inlet to the pressure switch valve (3 fig. 7)
will need cleaning.
4.3
GAS VALVE
The
“FORMAT”
boilers, are equipped stan-
dard with the SIT 837 TANDEM gas valve (fig.
27) and with HONEYWELL VK 4105M gas
valve (fig. 27/a). The gas valve is set at two
pressure values: maximum and minimum.
According to the type of gas burnt, these cor-
respond to the values given in
Table 4
. The
gas pressures at the maximum and mini-
mum 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 permitted to alter
the operating pressure.
It is essential that
this operation is carried out exclusively by
aut hor ized t echnical s t af f. When t he
working pressures have been adjusted,
reseal 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.
4.3.1
Maximum pressure adjustment
valve SIT
(fig. 28)
To set the maximum pressure, proceed as
follows:
–Connect the pressure column or a pres-
sure gauge to the pressure inlet down-
stream of the gas valve. In the
“30 BF”
versions, instead, connect the manome-
ter as shown in fig. 27/b.
–Remove the plastic cap (1).
–Set the knob of the D.H.W. potentiome-
ter to the maximum value.
–Ignite the boiler by operating the switch
and open the hot water tap.
– Using a ø 10 spanner, turn the nut (3) to
arrive at the maximum pressure value
given in
Table 4
: to reduce the pressure,
turn the nut counterclockwise; to increa-
se the pressure, turn it clockwise.
– Operate the main switch a number of
times, keeping the hot water tap open all
the time, and check that the pressure cor-
responds to the values given in
Table 4
.
4.3.2
Minimum pressure adjustment
valve SIT
(fig. 28)
After having adjusted the maximum pressu-
re, calibrate the minimum pressure as fol-
lows:
–Disconnect the electric power to the
modulator.
1
2
4 3
5
88
KEY
1
Modulator
2
EV1 - EV2 coils
3
Pressure inlet upstream
4
Pressure inlet downstream
5
VENT pressure test point
Fig. 27/a
TABLE 4
Burner max.
Modulator
Burner min.
Modulator
Type of gas
pressure
current
pressure
current
mbar
mA
mbar
mA
Methane - G20
9 - 11
130
2
0
Butane - G30
27 - 28
165
5
0
Propane - G31
35
165
5 - 7
0
Fig. 27/b
4
USE AND MAINTENANCE
Fig. 27
KEY
1
Modulator
2
EV1 - EV2 coils
3
Pressure inlet downstream
4
Pressure inlet upstream
5
VENT pressure test point