3.1
ELECTRONIC BOARD
The electronic boards are manufactured in
compliance with the EEC 73/23 low-voltage
directives. They are supplied with 230V and,
through a built-in transformer, send a volta-
ge of 24V to the following components:
modulator, C.H. sensor and time program-
mer. An automatic and continuous modula-
tion system enables the boiler to adjust the
heat output to the various system require-
ments or the User’s needs. The electronic
components are guaranteed against a tem-
perature range of –10 to +60°C.
3.1.1
Central heating operation
Upon demand for heating from the room
temperature stat, the circulation pump is
activated, and approximately 90 seconds
must elapse for the burner to start opera-
ting. This will happen only if the temperature
is set above the value detected by the hea-
ting sensor. The setting range is between
40 and 80°C. The heat output can be varied
according to the system needs by adjusting
the trimmer (1 fig. 21). At start-up of each
working cycle, after the period of slow igni-
tion having a duration of approx. 5 sec, the
boiler will set itself at the heat output set on
the “Minimum heating pressure” trimmer.
3.1.2
D.H.W. operation
Upon demand for hot water, the boiler
starts instantaneously when the microswit-
ch on the pressure switch valve trips. The
required power output is regulated, via
flame modulation, by the hot water sensor,
which will compare the temperature read
with the temperature set on the potentio-
meter. The adjustment range is between 40
and 60°C. When the heating flow sensor is
at 75°C the electronic limiter will trip and
switch-off the burner. The burner will re-igni-
te when the temperature falls below 2 °C.
3.1.3
Control leds
The electronic board is equipped with control
leds which show some of the possible failures
that can cause an irregular and/or improper
operation of the appliance. The leds are loca-
ted on the card as indicated in fig. 21 and
marked with the following wording:
–
“LD1 BLOCCO”
Red led on when control box, safety stat
and/or smoke stat trips.
–
“LD2 LINEA”
Green led off when there is no tension
present.
3.1.4
Devices available
on the electronic board
The electronic board is equipped with the
following devices:
–
“POT. RISC.” trimmer
(1 fig. 21)
Sets the maximum heating power value.
To increase the value turn the trimmer
clockwise; to reduce the value turn the
trimmer anticlockwise.
–
“POT. ACC.” trimmer
(6 fig. 21)
Trimmer to vary the pressure level upon
ignition (STEP), of the gas valve.
84
3
CHARACTERISTICS
2.10.6
“25 BF - 30 BF” wiring diagram with HONEYWELL control box
Fig. 20/c
KEY
EV1
Gas valve coil
EV2
Gas valve coil
EA
Ignition electrode
ER
Sensing electrode
A
HONEYWELL S4565CF control box
TS
100°C safety stat
PF
Smoke pressure switch
V
Fan
FL
Flowmeter
P
Circulation pump
VP
Divertor valve
TAG
Antifreeze stat (optional)
C
Rotary switch
TA
Room stat
M
Modulator
SM
S.H. sensor
Note: The room stat (TA) must be connected to the terminals 22-23
CONNECTOR SPARE
PART CODES:
J1
code 6260956
J2
code 6260959
J3
code 6260968
J5
code 6260964
