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Technical Documentation
Modulation board.
FUSE
NATURAL
GAS / LPG
Inside the CAESAR Star control box is a
microprocessor controlled electronic board that
integrates ignition and adjustment functions and, by
Operation.
When the master switch (S4) is in ON position it powers
the low-voltage circuit and enables appliance
operation.
If hot water is run the flow measuring device (B2) trips
and this gives the signal for burner ignition.
Afterwards, if the temperature detected by the d.h.w.
NTC sensor (B1) is below that set on the control panel
by means of the d.h.w. potentiometer (S4) the board
starts the fan (M1) and commands relay K1.
The consequent operation of fan (M1) results in closing
of fume pressure switch contact (S3) thereby allowing
the adjustment circuit to excite relay K2.
This way the board ignition circuit is enabled which
first of all commands the ignition electrode (E1) and
then, by means of relay K3, the main coils of gas val-
ve (Y1).
During the ignition phase, the power to the modulation
coil is gradually taken, in just 8 seconds, from minimum
to 50% of maximum.
Afterwards, the signal is increased so as to immediately
reach (if required) the maximum value set on the gas
valve.
During operation, flame modulation occurs with
reference to the difference between the temperature
set with the d.h.w. potentiometer (d.h.w. adjustment)
STCS ed 07/02
IGNITION TRANSF.
ON/OFF
D.H.W. ADJ.
MICROPROCESSOR
Technical Documentation
TOWN
GAS
means of LEDs, shows the operating condition of the
appliance, indicating any tripping of safety devices.
and the temperature read by the d.h.w. NTC probe
(B1).
When the set value is exceeded, the burner is kept
running at the minimum d.h.w. power (6,000 kcal/h)
and the contact of the relay K2 is opened (burner off)
only when the d.h.w. NTC probe (B1) reads a tempe-
rature above 66°C whatever the set temperature.
In this situation, the burner is turned on and off with
variable frequency in a way inversely proportionate to
the flow of water read by the flow measuring device in
order to keep the temperature constant.
If the water temperature drops below 54°C or a
considerable variation in flow is detected (about 1l/min),
burner ignition and switchoff occur with reference to
the temperature read by the d.h.w. NTC probe instead
of to the flow of water.
The modulation range (maximum and minimum)
during operation is regulated on the gas valve (see
gas adjustments).
15
Primary
Secundary
CAESAR Star
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