Sime Super four, Installation And Servicing Instructions

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8
between. This could occur in particu-
lar in systems presenting high head
losses. At each restart after the
period of slow ignition, the boiler will
set itself for about 1 minute at the
minimum modulation pressure, and
will then move to the heating pres-
sure value set.
When the connecting link is inser-
ted, both the programmed technical
pause and the period of operation at
minimum pressure in the start-up
phase will be cancelled.
In this case, the times elapsing
between turning off and subsequent
re-ignition will depend on a tempera-
ture difference of 8°C detected by
the SM sensor.
NOTE: It is essential that the opera-
tions described above be carried out
by authorized technical staff.
3.2TEMPERATURE SENSORS
The “SUPER FOUR” boilers are equip-
ped with sensors for detecting tempe-
rature:
– C.H. sensor, located on the outlet
pipe of the primary exchanger (SM)
– D.H.W. sensor located on the hot
water storage boiler unit (SS).
The sensors are NTC mod. ST03
ones and are interchangeable.
Table 2 shows the resistance values
that are obtained on the sensors as
the temperature varies.
NOTE: Should the SM sensor be
shorted, the boiler will not operate
either for central heating or for hot
water; should, instead, the SS sensor
be shorted, the boiler will operate
only for central heating.
3.3 ELECTRONIC IGNITION
The “SUPER FOUR” version boilers
are of the type with automatic ignition
(without pilot burner).
They are therefore equipped with FM
31 electronic control and protection (6
fig. 9). 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
Turn the switching knob located on
the control board to either SUMMER
or WINTER to check for presence of
voltage supply (green warning lamp
lights up).
The boiler is now ready to start
working upon demand for heating or
drawing off of domestic water; a
discharge current is sent to the igni-
tion electrode through the FM 31
programmer, and the gas valve opens
at the same time.
Burner ignition normally takes place
within 2 or 3 seconds starting from
the moment when the discharge cur-
rent reaches the ignition electrode.
However, it is possible for ignition failu-
res to occur, with consequent activa-
tion of signal indicating that the equip-
ment has “locked out”.
Failures may be due to one of the fol-
lowing causes:
– Gas failure
The appliance runs through the cycle
normally 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
equipment “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 tap being clo-
sed 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 bur-
ner is seen to open. After 10 sec.
the equipment “locks out”.
This may be due to a break in the
wire of the electrode, or the wire not
properly fastened to the equipment
electric terminal; or else, the tran-
sformer has burnt out.
– 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.
This occurs when the position of line
and neutral has not been respected
on the terminal block.
There is a break in the wire to the
sensing electrode, or the electrode
itself is touching earth; the electrode
is worn out and needs replacing.
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 SMOKE PRESSURE
SWITCH
The smoke pressure switch is located
inside the sealed- room (7 fig. 3).
To gain access to the pressure switch,
first you must release the four hinges
and remove the fixing screw of the
front wall.
A Venturi tube system, fastened inside
the fan unit and connected to the pres-
sure switch by means of two silicone
pipes, ensures start-up of the burner
only when the fan is operating.
Impurities and possible formations of
condensate, which are more likely in
cold periods of the year, could cause
the pressure switch not to function
and the boiler to fail to start. The pres-
sure switch is set in the factory at the
optimal values of 8-9 mm H
2
O.
This is able to guarantee operation of
the boiler even with air intake and flue
outlet pipes have the maximum limit of
length allowed.
3.5 WATER FAILURE
SAFETY DEVICE
The boiler is equipped with a water
pressure switch (8 fig. 13) set at 0.6
bar, which goes into action, blocking
boiler operation, whenever the pressu-
re inside the boiler is less than the cali-
bration value.
When the pressure switch trips, a
red warning lamp starts flashing (11
fig. 11). To restore burner operation,
turn the charge cock and bring the
pressure back to a value between
1
and 1.2 bar .
Temperature °C Resistance
Ω
20 12,000
30 8,300
35 6,900
40 5,800
45 4,900
50 4,100
55 3,500
60 3,000
70 2,200
80 1,700
TABLE 2