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MAIN ELECTRONIC CONTROL/IGNITION P.C.B.
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.
Figure 9 .2
1 2
16
3 4
5
6
10
11
11 12
13
14
15
7
8
9
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
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
or
.
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.
Figure 9 .3
Summary of Contents for M275V.2024 SM
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