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3.3
EXTERNAL SENSOR
ENG
If there is an external sensor, the heating
IT
settings SET can be taken from the climatic
curves according to the external tempera-
ture and, in any case, limited to with the
ES
range values described in point 3.2 (para-
meters PAR 13 and PAR 14).
The climatic curve to be set can be selected
from a value of 3 and 40 (at step 1).
Increasing the steepness of the curves of
fig. 13 will increase the output temperature
as the external temperature decreases.
3.4
CARD FUNCTIONING
The electronic card has the following functions:
– Antifreeze protection of the heating circuit.
– Ignition and flame detection system.
– Control panel setting for the power and
the gas for boiler functioning.
– Anti-block for the pump which is fed for a
few seconds after 48 hours of inactivity.
– Chimney sweep function which can be
activated from the control panel.
– Temperature which can be shifted with
the external sensor connected.
It can be set from the control panel.
– Automatic regulation of the ignition
power
and
Adjustments are managed automatically
by the electronic card to guarantee maxi-
mum flexibility in use of the system.
3.5
THERMISTOR VALUES
Table 6 gives the values of the electrical
element (Ω) obtained on the heating and
sanitary water sensors according to the
variations in temperature.
The C.H. sensor (SM1/SM2) is of type to
double sensing element with function safety
thermostat.
When the heating sensor (SM1/SM2) is
interrupted, the boiler will not function
for both services.
With the D.H.W. sensor (SS) interrupted,
the boiler functions only in D.H.W. mode.
3.6
ELECTRONIC IGNITION
Ignition and flame detection is controlled by
a single electrode on the burner which gua-
TABLE 6
Temperature (°C)
20
30
40
50
60
70
80
rantees reaction in the case of accidental
extinction or lack of gas within one second.
20
maximum
heating.
3.6. 1
Burner ignition occurs within max. 10
seconds after the opening of the gas valve.
Ignition failure with consequent activation of
block can be due to:
– Lack of gas
– The electrode does not discharge.
Resistance (Ω)
12.090
8.313
5.828
4. 1 61
3.021
2.229
1.669
In the case of a sudden lack of voltage, the
burner will immediately switch off. When
voltage returns, the boiler will automatically
start up again.
ATTENTION: curves are calculated at an ambient temperature of 20°C.
Using the
key on the control panel, the user can change the set
ambient by ± 5°C for which the curve is calculated.
Functioning cycle
The ignition electrode persists in dischar-
ging for max. 10 seconds.
If the burner does not ignite, the anomaly
is signalled. This can happen the first
time the boiler is switched on after a long
period of inactivity due to the presence of
air in the gas pipes.
It can be caused by a closed gas cock or
by a faulty gas valve.
In the boiler, only the opening of the gas
to the burner can be detected. After 10
seconds the error is signalled.
It can be caused by an break in the elec-
trode wire or if it is incorrectly connected
to the connection points.
Or the electrode may be earthed or
damaged: it must be replaced.
Or the electronic card may be defective.
3.7
AIR PRESSURE SWITCH
The pressure switch is calibrated by the
manufacturer at the following values:
0.62 - 0.72 mm H
O which can guarantee
2
boiler operation also with int ake and
discharge pipes of the maximum length
allowed.
The value of the signal to the pressure swit-
ch is measured by a differential pressure
gauge connected as indicated in fig. 14.
3.8
WATER PRESSURE SWITCH
The water pressure switch (C fig. 15) inter-
venes, stopping the boiler, if it detects that
there is insufficient pressure in the boiler
(< 0,6 bar).
To restore burner functioning, to bring back
the pressure of the boiler to between 1 -
1.2 bar.
3.9
HEAD AVAILABLE TO SYSTEM
Residual head for the heating system is
shown as a function of rate of flow in the
graph in fig. 5.
To obtain the maximum head available to
the system, turn off the by-pass by turning
the union to the vertical position (fig. 15).
Fig. 13
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