3.1
ELECTRONIC CONTROL BOX
The boiler is supplied with HONEYWELL
S4565C electronic control box.
Ignition and flame detection is controlled by
an electrode located on the burner, which
guarantees maximum safety with interven-
tion times, for accidental switching off or
gas failure within one second (fig. 8).
3.1.1
Operating cycle
Normally the burner takes 1 or 2 seconds
to light. However, it is possible for ignition fai-
lures to occur, with consequent activation of
signal indicating that the control box has
“locked out”.
–
Gas failure
The control box runs through the cycle
normally sending electric power to the
ignition electrode. The electrode conti-
nues 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 win-
ding, so that the valve cannot open.
–
The ignition electrode does not emit
the spark
In the boiler you can only see that gas is
sent to the burner, after 10 seconds the
appliance is stopped. This may be due to
an electrode wire that is broken or that
has not been properly fixed to the termi-
nal of the equipment; or the transformer
of the equipment may be burnt.
–
No flame is detected
From the time of the starting you can
observe the electrode continuos spark-
ing even if the burner is on. After 10 sec-
onds the sparking stops and so does the
burner, while the lock-out lamp appears
to be on.
It occurs if the phase and neutral position
on the terminal board has not been
observed. The detection electrode cable
is disconnected or the electrode itself is
earthed; the electrode is very worn-out
and needs replacing.
The control box is defective.
The sudden lack of voltage causes the
immediate shutdown of the burner and
when the voltage is restored the boiler will
automatically restart.
3.1.2
Operating cycle
During each start-up the programmer car-
ries out self-checking which will not allow
s t a r t - u p i n c a s e o f d e f a u l t o r i f a
parasitic flame signal is detected, The pro-
grammer will not start even if the air pres-
sure switch is not on the no- ventilation
position.
3.2
SMOKE PRESSURE
SWITCH
(fig. 9)
The pressure switch with fixed settings is
able to guarantee the boiler operation even
with air intake and smoke outlet pipes at the
maximum limit of the length allowed
The signal value at the pressure switch is
measured by means of a differential pres-
sure gauge that is connected to the posi-
tive and negative pressure intakes located
onthe hermetically sealed chamber.
3.3
HEAD AVAILABLE
FOR THE SYSTEM
Residual head for the heating system is
shown as a flow rate function in the graph
in fig. 10.
43
3
CHARACTERISTICS
2
1
3
Fig. 8
Fig. 9
500
1000
1500
2000
2500
0
100
200
300
400
500
Portata l/h
Pr
evalenza r
esidua (mbar)
BITHERM BF
3000
Fig. 10
KEY
1
Burner
2
Detection electrode
3
Ignition electrode
FLOW RATE l/h
RESIDU
AL
HEAD
(mbar)
