85
According to the type of gas for which the
boiler is equipped, the trimmer must be
regulated so as to obtain a pressure of
approx. 3 mbar at the burner for metha-
ne gas and 7 mbar for butane gas (G30)
and propane gas (G31). To increase pres-
sure, turn the trimmer clockwise; to redu-
ce pressure, turn the trimmer counter-
clockwise. The slow ignition pressure level
can be set during the first 5 seconds fol-
lowing burner ignition.
After setting the
pressure level upon ignition (STEP)
according to the type of gas, check that
the pressure for heating is still at the
value previously set.
–
“GPL-MET” connector
(4 fig. 21)
The connector link must be inserted on
the type of gas for which the boiler is
equipped.
–
“ANN. RIT.” connector
(5 fig. 21)
In the heating phase, the electr onic
board is programmed to include a bur-
ner technical delay interval of approx. 2
minutes, which occurs both at system
cold starting and at subsequent re-igni-
tions. The aim is to overcome the pro-
blem of repeated ignitions and turning off
with very short time intervals between.
This could occur in particular 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 pressu-
re value set. When the connecting link is
inserted, both the programmed technical
pause and the period of operation at
minimum pressure in the startup phase
will be cancelled. In this case, the times
elapsing between turning off and subse-
quent re-ignition will depend on a tempe-
rature difference of 3°C detected by the
SM sensor (heating flow sensor).
ATTENTION: It is essential that the opera-
tions described above be carried out by
authorized technical staff.
3.2
TEMPERATURE SENSOR
The
“FORMAT”
boilers are equipped with
sensor for detecting temperature:
The probe acts as a limit thermostat, swit-
ching-off the burner when the temperatu-
re measured is higher than 90° C; the
reset temperature is set at 80°C.
When probe (SM) has tripped, the boiler
will not function for either service. Table
3
shows the resistance values (
Ω
) that
are obtained on the sensor as the tempe-
rature varies.
In case of replacement, the thermistor will
have to be fitted onto the relevant clew,
located on the flow pipe (fig. 22).
3.3
CONTROL BOX
The boilers are equipped with HONEYWELL
S4565CF and/or SIT 503 electronic con-
trol and protection. Ignition and flame detec-
tion 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
Before igniting the boiler, use a voltmeter to
make sure that the electrical connection to
the terminal block has been made properly,
respecting the position of line and neutral,
TABLE 3
Temperature (°C)
Resistance (
Ω
)
20
12.764
30
8.579
35
7.102
40
5.915
45
4.955
50
4.173
55
3.533
60
3.006
70
2.208
80
1.650
Fig. 22
CLEW
Fig. 21
KEY
1 “Heating output” trimmer
2 Fuse (1.6 AT)
3 D.H.W. potentiometer
4 “GPL-MET” bridge
5 “Cancel delay” bridge
6 “Ignition pressure” trimmer
7 “LD1 Block” led
8 Heating potentiometer
9 “LD2 Line” led
NOTE: To gain access to trimmers
(1) and (6), unscrew the central
heating potentiometer knob.
2
1
5
9
8
7
3
6
4
6
1
C
