Technical documentation
Technical documentation
STEM@ ed 06/01
20
EOLO MAIOR @
ELECTRICAL CIRCUIT
CENTRAL HEATING PHASE
(*) the main coils of the gas valve run at mains voltage rectified by means of a diode bridge (U1) only on the
Honeywell VK 4105 gas valve (diode bridge fitted on the valve connection connector)
Operation with room thermostat
When the main switch (S5) is in WINTER position, it powers the modulation board and enables
operation in central heating mode.
When the room thermostat (TA) contact is closed, the low-voltage circuit starts the pump (M1)
through relay contact K1.
If the system water pressure switch (S7) reads a pressure in the primary circuit above minimum
value (
S7 switch closed
) and if the temperature read by the NTC heating sensor (B1) is below the
setting made on the control panel by means of the heating potentiometer, the board closes the
contact of the requested relay (K2).
This way, the ignition unit (IGNITION CARD) starts the ignition cycle by first checking the correct
position of the flue pressure switch (S4) and then powering fan (M2).
After the contact of flue pressure switch (S4) has been deviated by fan operation (M2), the unit
(IGN. CARD) powers the ignition electrodes (E1-E2) and, with the consensus of the overheat. safety
thermostat (E4), the main coils of gas valve (Y1).
Burner ignition is detected by the unit by means of the ionisation electrode (E3).
Operation with Remote Friendly Control
The min switch (S5) in "SUMMER and CAR" position powers the modulation board and remote
control (CAR).
If the conditions found by the remote control (CAR) require ignition in central heating phase
(
SUM/WINT switch in WINTER position, central-heating temperature adjustment above that read
by the central-heating sensor (B1), room temperature adjustment above that read)
, the board
powers pump (M1) through relay K1 and ignition occurs as described above.
NOTE
: In both cases, at each switch-off due to temperature having been reached, the modulation
board stops burner operation during central-heating phase for 180 sec., which can be reduced to 30
seconds by intervening on the special bridge “S2”
(see modulation card operation).
