23
ENG
3.3 ELECTRONIC IGNITION
Ignition and flame detection is controlled by
an electrode located on the burner. These
guarantee maximum safety with intervention
times, for accidental switching off or gas failu-
re, of within one second.
3.3.1 Operating cycle
Rotate the rotary switch to summer or winter,
the red led should light up.
Burner ignition normally takes place within 10
seconds. However, it is possible for ignition failu-
res to occur, with consequent activation of signal
indicating that the control box has “locked out”.
– Gas failure
The control box runs through the cycle nor-
mally sending electric power to the ignition
electrode. The electrode continues spark
discharge for a maximum of 10 sec. If the
burner does not ignite, the control box “locks
out”.
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 control box “locks
out”.
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 ignition transfor-
mer.
The electrode is earthed or very worn and
needs to be substituted. The control box is
defective.
When there is a sudden voltage failure, the bur-
ner shuts out immediately; when power supply
returns, the boiler will start up again automa-
tically.
3.4 SMOKE PRESSURE
SWITCH
(fig. 16)
The pressure switch with fixed settings: 4.6-5.6
mmH
2
O (0.18-O.22 ”W.C.H
2
O), is able to gua-
rantee the boiler operation even with air intake
and smoke outlet pipes at the maximum limit of
the length allowed.
The value of the signal to the pressure switch
is measured by means of a manometer con-
nected as shown in fig. 16.
3.5 FLOW SWITCH SAFETY VALVE
The flow switch (8 fig. 5) is tripped and stops
the burner when it does not detect water flow
in the primary circuit > 400 l/h (1.76 USgpm).
To restore burner functioning, check system
pressure and the functioning of the pump and
the flow switch, and the cleaning of the “Aqua
Guard Filter System” filter.
NOTE: If replacing the flow switch valve, make
sure that the arrow stamped on the valve
points in the same direction as the flow of
water.
3.6 HEAD AVAILABLE TO SYSTEM
Residual head for the heating system is shown
as a function of rate of flow in the graph in fig.
17.
Figure 16
Figure 17
RESIDUAL HEAD VERSUS FLOW FOR HEATING SYSTEM
0
100
200
300
400
500
600
0 200 400 600 800 1000 1200
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