Immergas NIKE Mini 24 Export Manual page 28

Technical Documentation
Modulation board.
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Inside the boiler's control panel is a p.c.b. that controls the
appliance's electrical devices and sees to the linear modulation
of burner power.
The appliance's functioning status is shown on a display, indi-
cating if any of its safety devices have triggered.
This board is used on all models, whether they are the
conventional or sealed chamber type (NIKE/EOLO Mini
24-28, NIKE/EOLO Mini 24 S). The different boiler func-
tioning modes are recognised automatically by means of the
appliance's wiring.
The integrated board is always powered regardless of the operat-
ing positioned determined by the functioning knob (S2).
The board executes a periodical self-check to make sure it is
working properly. During the central heating functioning
mode or with the boiler in Stand-by, this function is activated
every 18 hours from the last boiler check/powering. During
the d.h.w. functioning mode, this self-check starts within
10 minutes from the last time water was drawn and lasts 10
seconds.
NOTE: the boiler stops working (together with indications)
during the self-check operation.
Operation.
Central heating request.
By selecting the (Winter), functioning mode with the
(S2) push button, the boiler is enabled to work in the central
heating mode.
When the room thermostat (S20) closes the integrated board
powers the boiler circulator (M1) by means of the K3 relay.
The integrated board, enabled by the safety thermostat (E4)
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Technical Documentation
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and fumes thermostat (E6) and if the temperature measured
by the delivery probe (B1) is below the value set on the boiler's
control panel, energises the request relay K2 that causes the 2
contacts to close which allows the ignition cycle to start.
During the first few seconds after the gas valve (Y1) has been
powered, the current to the modulating coil (Y2) is limited to
the predefined soft ignition current.
The burner will then go to the minimum value set by setting
the "Minimum Central Heating Power*" parameter and
then reach the maximum value set (if required) by setting the
"Maximum Central Heating Power*" parameter in a time set
in the "Central Heating Ramp Time*" parameter.
Subsequently the signal is varied directly proportionate to the
difference between the temperature set on the boiler control
panel and the temperature measured by the delivery probe
(B1).
When the set temperature (+5°C) is exceeded, the contact of
relay K2 is opened and the burner switched off. Re-ignition
time depends on how the "Central Heating Ignitions Timer*"
parameter is set.
Each time the burner switches off the circulator keeps working
for another 30 seconds.
* see Integrated board programming.
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NIKE Mini Export