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9 .2 Selection and adjustment devices
On the Main electronic control/ignition p.c.b. several selection,
adjustment and protection devices are located. (Figure 9.2).
Some of these devices are directly accessible by the user (func-
tion control, temperature adjustment etc.) others, like the fuses,
are accessible by removing the main electronic p.c.b. lid.
1
2
3
4
16
15
Figure 9 .2
1 Connector - electric supply p.c.b.
2 Connector - fan
3 Connector - pump
4 Connector - gas valve
5 Connector - ground reference for ignition / detection elec-
trode
6 Connector - ignition / detection electrode
7 Connector - external temperature probe and remote control
(optional)
8 Connector - controller pump
9 Connector - controller fan
10 Connector - D.H.W. outlet temperature probe NTC
11 Connector - safety thermostat and C.H. temperature probe
NTC
12 Connector - primary circuit pressure switch
13 Connector - safety thermal fuse
14 Connector - D.H.W. flow switch
15 Connector - 3 way diverter valve
16 Fuse F1 3,15 AF
MAIN ELECTRONIC CONTROL/IGNITION P.C.B.
5
6
14
13
11 12
11
10
9 .3 Checking the temperature
The Main electronic control/ignition p.c.b. makes it possible to
separately adjust the C.H. water flow temperature and D.H.W.
outlet temperature.
The temperature of the water is converted into an electric signal
by means of temperature probes.
The user, setting the desired temperature with the control panel
p.c.b. key
If the power requested is lower than 40% of the maximum power
output then control is achieved by switching ON the burner at
minimum power, then switching OFF (ON/OFF function). If the
power requested is higher, then the burner is switched ON at
maximum power and will control by modulating to 40% of the
maximum power output.
During the C.H. operation (Figure 9.3), the signal coming from
the C.H. temperature probe is compared to the signal given by
the control panel through the adjustment made by the user (key
). The result of such a comparison operates the fan
speed thus regulating the gas flow rate and consequently chang-
ing the useful output of the boiler.
7
8
9
Figure 9 .3
or
.
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