Immergas EOLO Mini Technical Documentation Manual page 24

Technical documentation Technical documentation
MODULATION BOARD
Inside the EOLO MINI control box is a microprocessor-controlled electronic board that, besides
performing the operations of the board equipping the NIKE Mini, controls the fan (MV) and flue
pressure switch (SV).
The EOLO Mini board can also be used on the NIKE Mini (and not vice versa) without any
adjustment or controls and safety device bypass being required.
N.B.: from the serial number 2238340 the p.c.b. has been modified due to the change of the safety
thermostats (see p.c.b. safety devices).
The new p.c.b. can replace the old one, but the contrary is not advisable because could trip the
overheating safety (TS1).
In any case, it is best to use the board equipping the ZEUS Mini boiler as a spare part as this,
after being suitably adjusted (see ZEUS Mini technical sheet), can be fitted to all the Mini versions
(NIKE, EOLO, ZEUS).
- OPERATION
Heating request
When the main switch (IG) is in WINTER position and the room thermostat (TA) contact is closed,
the adjustment circuit starts the circulator by means of the PUMP RELAY.
If the temperature read by the NTC delivery sensor (NM) is below that set using the heating
potentiometer (C.H.), the board powers the fan (MV) by exciting the FAN RELAY.
Consequent operation of fan (MV) causes the flue pressure switch contact (SV) to close, thereby
permitting the adjustment circuit to excite the REQUEST RELAY.
This way, the board ignition circuit is enabled.
This first of all triggers the ignition electrodes (E1 - E2) and then, by means of the RELAY V/G, the
main coils of gas valve (VG).
During the ignition phase, the pulse signal sent to the modulation coil is restricted by the setting
made by means of the soft ignition trimmer (IGN. POWER.), while afterwards, after detecting the
presence of the flame by means of the ionisation electrode (E3), this goes to the minimum value set
on the gas valve.
24
STEME ed 07/03 EOLO MINI