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1
2
3
4
5
minimum modulation pressure, and will
then move to the heating pressure value
set. When the connecting link is inserted,
both the programmed technical pause
and the period of operation at minimum
pressure in the startup phase will be can-
celled. In this case, the times elapsing
between turning off and subsequent re-
ignition will depend on a temperature dif-
ference of 5°C detected by the SM sen-
sor (heating flow sensor).
ATTENTION: It is essential that the opera-
tions described above be carried out by
authorized technical staff.
3.2
TEMPERATURE SENSOR AND
WATER PRESSURE TRANSDUCER
Tables 3 - 3/a show the resistance values
(Ω) that are obtained on the sensor as the
temperature varies and the transducer val-
ues obtained as the pressure varies.
When sensor (SM) is interrupted, neither
of the boiler's heating services will func-
tion. With sensor (SS) interrupted, the
boiler will only work in heating mode.
TABLE 3 (Sensors)
Temperature (°C)
Resistance (Ω)
20
30
40
50
60
70
80
12
12
11
10
9
KEY
1 Ignition electrode earth fastener
2 Ignition electrode faston
3 Fuse (1,6 AT)
4 Fuse (0, 1 6 AT)
5 "ANN. RIT." connector
6 "POT. ACC." trimmer
7 Conector "MET-GPL"
8 D.H.W. potentiometer
TABLE 3/a (Transducer)
Pressure
(bar)
3.3
ELECTRONIC IGNITION
Ignition and flame detection is controlled by
two electrodes located on the burner.
These guarantee maximum safety with
intervention times, for accidental switching
off or gas failure, of within one second.
3.3. 1
Operating cycle
Rotate the selector knob to summer or win-
ter, and verify that green led (
confirm the presence of voltage.
The boiler is now ready to start working
upon demand for heating or drawing off of
D.H.W.; a discharge current is sent to the
ignition electrode, and the gas valve opens
at the same time. The burner must be ignit-
ed within 10 seconds.
However, it is possible for ignition failures
12.090
to occur, with consequent activation of sig-
8.313
nal indicating that the control box has
5.828
"locked out".
4. 1 61
3.021
– Gas failure
2.229
The control box runs through the cycle
1.669
normally sending electric power to the
8
7
6
15
9Detector electrode faston
10 "POT. RISC." trimmer
11 C.H. potentiometer
12 Selector CR/OFF/D.H.W./C.H./RESET
NOTE: To gain access to trimmers (8) and
(14), unscrew the central heating poten-
tiometer knob.
Resistance (Ω)
mín
máx
0
297
320
0,5
260
269
1
222
228
1,5
195
200
2
167
173
2,5
137
143
3
108
113
3,5
90
94
) lights up to
6
10
ignition electrode. The electrode contin-
ues spark discharge for a maximum of
10 sec.If the burner does not light, the
lock-out indicator will light up.
This may occur upon first ignition or after
long periods of boiler lay-off when there is
air in the pipes. It may be caused by the
gas cock being closed or by one of the
valve coils having a break in the winding,
so that the valve cannot open.
– Ignition electrode fails to spark
In the boiler, only the gas to the burner
is seen to open.
After 10 sec. the warning light indicat-
ing equipment "lock-out" lights up.
This may be due to a break in the wire of
the electrode or to the wire not properly
fastened to the electric terminal of the
control box;
– No detection of flame
The continuous spark discharge of the
electrode is noted starting from ignition
even though the burner is lit.
After 10 seconds have elapsed, the
sparks cease, the burner goes out, and
the warning light indicating equipment
"lock-out" lights up.
There could have a break in the wire of
the sensing electrode or the electrode
itself is touching earth: the electrode is
worn out and needs replacing. The con-
trol box is defective.
When there is a sudden voltage failure, the
burner shuts out immediately; when power
supply returns, the boiler will start up again
automatically.
3.4
FLOW SWITCH SAFETY VALVE
Fig. 16
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