3.1
CONTROL BOX
The boiler is equipped with FM 12 elec-
tronic control and protection. Ignition
and flame detection are controlled by
two electrodes which guarantee maxi-
mum safety with inter vention times,
within 1 second for accidental switching
off or gas failure.
3.1.1
Operating cycle
Before igniting the boiler, use a voltmeter
to make sure that the electrical connec-
tion t o t he t erminal block has been
installed properly, with respect to the
position of the live and neutral points, as
shown in the diagram.
Then press the switch on the terminal
block so that the boiler begins to operate
upon request either for heating or for
drawing hot water: a discharge current
is sent to the ignition electrode through
the FM 12 programmer, and the gas
valve opens at the same time.
Burner ignition normally takes place
within 2 or 3 seconds from the moment
that electric discharge on the ignition
electrode has begun.
When the pilot burner is turned on the
FM12 device opens the second electric
valve and proceeds to the ignition of the
principal burner. However, it is possible
for ignition failures to occur, with conse-
quent activation of the signal indicating
that the equipment has "locked out". Fai-
lures may be due to one of the following
causes:
- 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 60 sec.
If the pilot burner does not ignite, the
control box "locks out".
This may occur upon first ignition or
af ter long periods of boiler lay-of f
when there is air in the pipes.
It may be caused by the failure of the
gas valve to open owing to a break in
the electric coil.
– Ignition electrode fails to spark
In the boiler, only the opening of gas to
the burner appears to occur. After 60
sec. the control box "locks out".
This may be due t o ther e being a
break in the wire of the electrode or
the wire not being properly fastened
to the terminal of the control box; or
alternatively, the transformer has
burnt out.
– No detection of flame
The continuous spark discharge of the
electrode is noted to continue starting
from ignition even though the pilot bur-
ner is lit. After 60 seconds have ela-
psed, the sparks cease, the burner
goes out, and the warning lamp indica-
ting equipment "lock-out" lights up.
This occurs when the positions of live
and neutral have not been respected
on the terminal block. There is a break
in the wire of the sensing electrode or
the electrode itself is ear thed: the
electrode is worn out and needs repla-
cing. The control box is faulty.
When there is a sudden voltage failure,
the burner shuts down immediately;
when the power supply returns, the boi-
ler will start up again automatically.
3.2
REGULATING THERMOSTAT
"EKO OF"
boilers are equipped with a
regulating thermostat with a double con-
tact having differentiated settings (6 fig.
2). This makes it possible to obtain a
reduction of heat output before the bur-
ner goes out completely, by means of the
coil assembly installed on the gas valve
regulator.
This step-modulation system affords the
following advantages:
– higher overall boiler efficiency;
– containment within acceptable values
of the increase in temperature that
takes place in the cast-iron body (heat
inertia) when the burner goes out.
3.3
SMOKE SAFETY DEVICE
‘EKO 3/6 OF - 3/4 OF PVA’
This is a safety device against possible
smoke emission into the environment
due to inefficiency or partial obstruction
of the flue.
The safety device goes into action by
blocking operation of the gas valve when
the return of the smoke into the environ-
ment is continuous and in possibly dan-
gerous quantities.
The device’s intervention consists in the
‘locking out’ of the control box because
the burner fails to be ignited; in this case,
press the release button and the boiler
will start up again automatically.
Should the boiler continue to "lock out", it
will be necessary to make a careful check
of the flue pipe, making all the necessary
modifications and amendments so that it
can work properly.
3.4
RESIDUAL PREVALENCE IN
THE ‘3/4 OF PVA’ SYSTEM
In the diagram fig. 8, you can see the
representation of the residual prevalen-
ce in function of the capacity, within the
heating plant.
3.5
LOSS OF LOAD
BOILER CIRCUIT ‘3/12 OF’
The load losses are shown in the diagram
of fig. 8/a.
31
IT
GB
FR
BE
DE
3
FEATURES
200
150
100
50
0
100
200
Portata l/h
∆
p mbar
250
300
0
350
400
450
300
400
500
600
800
1000
2000
2500
1500
500
550
600
3 OF PVA
4 OF PVA
Fig. 8
Flow rate l/h
