Technical documentation
Technical documentation
STEM@ ed 06/01
22
EOLO MAIOR @
MODULATION CARD
All the models of the Eolo Maior @ series feature a microprocessor-controlled electronic board inside
the control panel for controlling the electrical devices of the appliance.
This occurs by combining with a special electrical coil that operates directly on the stabiliser of the gas
valve which is controlled by variable D.C. current, the intensity of which is directly proportionate to the
gas pressure to the burner.
The board is powered with the master switch (S5) in position
(summer)
or
(winter).
NOTE: by means of a special kit, the board used on the models of the
Maior @ and Eco @ series can
also be fitted to previous MAIOR versions,
except for the EOLO 21 Pilota Maior.
The kit comprises an interface cable, an adhesive to change the screen print on the panel and an
instruction leaflet showing the various error codes.
- OPERATION
Heating request with room thermostat
When the main switch is in WINTER position and the room thermostat (TA) contact is closed, the low-
voltage circuit starts the circulator (M1) and powers relay K1.
If the system water pressure switch contact (S7) is closed and the temperature read by the NTC heating
sensor (B1) is below that set using the heating potentiometer (C.H.), the low-voltage circuit excites relay
K2. This results the ignition card powering and the start of the ignition cycle.
After the gas valve (Y1) has been powered, during the first 5 seconds, power to the modulation coil is
restricted by the adjustment made with the soft ignition trimmer (IGN. POWER) while during the next
60 seconds, this achieves the setting made with the central-heating minimum power trimmer (C.H. MIN.
POWER).
Subsequently the signal is changed in a way directly proportionate to the difference between the
temperature set with the central-heating potentiometer (C.H.) and that read with the NTC heating sensor
(B1) and, if necessary, reaches the figure set with the maximum heating power trimmer (C.H. MAX
POWER) in 13.5 minutes.
Once the set temperature is exceeded, the contact of relay K2 is opened with consequent switch-off of
the burner. This cannot be started again for the same request for 180 s / 30 s (
see central heating timer
switch “S2”).
