27
flow temperature sensor. When the fan is sensed
to be operating correctly, the ignition sequence
commences.
Ignition is sensed by the electronic circuitry to
ensure flame stability at the burner. Once suc-
cessful ignition has been achieved, the electronic
circuitry allows 75% 0f the full gas rate through
the appliance. After 15 minutes (adjustable, see
parameter 28, cap. 7.3.1) the gas rate is increased
to maximum (100%).
The speed of the fan and therefore the output of the
boiler is determined by the temperature of the
water sensed by the flow temperature sensor,
consequently a high temperature at the flow sen-
sor results in a lower fan speed. As the water
temperature increases, the temperature sensors –
located on the flow pipe of the boiler – reduce the
fan speed via the electronic circuitry. Depending
on the load, either the water temperature will
continue to rise until the set point is achieved or
the water temperature will fall whereby fan speed
will increase relative to the output required. When
the boiler has reached the set point, the burner will
switch off. The built-in anti-cycle device prevents
the burner from re-lighting for an adjustable period
of time (factory default is 5 minutes). When the
temperature of the flow sensor falls below the set-
point, the burner will re-light.
NOTE
If the spark/sensing electrode does not sense
ignition the appliance will re-attempt ignition a
further 4-times then go to lockout.
When the set-point has been reached (the position
of the heating temperature selector) as measured
at the primary thermistor, the appliance will begin
the modulation phase whereby the fan and gas
valve will continuously modulate to maintain the
set-point.
If the temperature continues to rise and exceeds
the set-point by 6°C, the burner will shut down. A
new ignition sequence will be enabled when the 5-
minute anti-cycle has been performed and the
temperature at the primary thermistor has dropped
6°C below the set-point.
NOTES
Any DHW request will always have priority over
the heating request.
When the request for heating has been satisfied,
the appliance pump and fan may continue to
circulate to dissipate any residual heat within the
appliance.
7.2.8
DHW MODE
When the ON/OFF selector is in the ON position
and a DHW outlet is opened, the appliance will
operate in the HW mode. The valve actuator will
motor to the HW position (if a heating request was
active) and the pump and fan will be activated via
the flow temperature sensor. When the fan is
sensed to be operating correctly, the ignition
sequence commences. Ignition is sensed by the
electronic circuitry to ensure flame stability at the
burner.
Once successful ignition has been achieved, the
electronic circuitry modulates the appliance out-
put in order to achieve the DHW set-point (the
position of the DHW temperature selector) as
measured at the DHW thermistor.
When the set-point has been reached, the appli-
ance will begin the modulation phase whereby the
fan and gas valve will continuously modulate to
maintain the set-point.
If the temperature continues to rise and exceeds
the set-point by 5°C, the burner will shut down until
the temperature drops to set-point + 4°C, whereby
a new ignition sequence will be enabled.
If the TSC function is active the set point will be
overridden until/unless the appliance reaches the
maximum operating temperature.
When the request for DHW has been satisfied, the
appliance fan may continue to operate to dissipate
any residual heat from within the appliance.
7.3
SERVICE MODE & PARAMETERS
To check or adjust the service parameters you
must first access the service mode. This mode is
only accessible in OFF mode. To access the
service mode: push INFO and MODE buttons at
the same time for 10 seconds to enter the adjust-
ing menu.
The display shows “CodE” (see fig. 41). Push
MODE button and select the service parameters
code by turning the DHW temperature control and
confirm it by pushing MODE button.
7.3.1
PARAMETERS SETTING
Turn the DHW temperature control to display all
parameters and their values (see fig. 42). When
the required parameter is displayed, push the
MODE button, the current (parameter) value will
flash. To change the parameter value, rotate the
DHW temperature control until the required value
is displayed, push the MODE button to store the
new value. To exit the service mode push INFO
button.
Fig. 41
MODE
INFO
Fig. 42
Parameter value
Parameter number
