Immergas EOLO Superior PLUS 24 Guide

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EOLO SUPERIOR PLUS
EOLO Superior PLUS
Wall-hung boiler with sealed
combustion chamber and fan-
assisted with external storage tank
EOLO 24 Superior PLUS
- GENERAL FEATURES
The EOLO Superior Plus is a wall boiler designed to be used together with PLUS storage
tanks ( 80 l, 105 l and 120 l).
Adjustment and control of the two units are entrusted to a microprocessor-controlled
electronic board which, thanks to a display, shows operating conditions (settings,
temperatures, safety devices, etc.).
The boiler has an efficiency over 90% and features a standard anti-frost device which
protects it down to temperatures of -5°C.
The hydraulic circuit features a high-head copper water-gas exchanger, an electric 3-way
valve and an adjustable system by-pass.
Combustion air flow into the sealed chamber and flue extraction are ensured by a fan, the
correct operation of which is controlled by a differential pressure switch.
The appliance is prearranged for the connection to a remote control panel (see Remote
Friend Control technical sheet), to the area control unit (see area control unit technical
sheet) and to the Multisystem Water Disconnector (see D.I.M. technical sheet).
The AISI 316 L STAINLESS STEEL storage tanks feature a standard anode and expansion
vessel and can be connected to the re-circulation system by means of a special kit (optional).

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EOLO SUPERIOR PLUS
MAIN DIMENSIONS AND CONNECTIONS
BOILER
DIMENSIONS (mm)
HEIGHT WIDTH DEPTH
850 450 350
CONNECTIONS
GAS SYSTEM
GRB-MB RI-MI
1/2 “ 3/4 “ 3/4 “
V - power connection
G - gas supply
RB - boiler return
MB - boiler flow
A - system filling
RI - system return
MI - system flow
STORAGE TANK UNIT
DIMENSIONS (mm)
80 l 105 l 120 l
HEIGHT 850 1020 850
WIDTH 500 500 600
DEPTH 500 500 600
CONNECTIONS
SYSTEM DOMESTIC HOT WATER
RB-MB EURC
3/4 “ 1/2 “ 1/2 “ 1/2 “
V - power supply
U - d.h.w. outlet
RB - boiler return
MB - boiler flow
E - d.h.w. inlet
RC - recirculation (optional)

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EOLO SUPERIOR PLUS
EOLO Superior PLUS MAIN COMPONENTS
1 - Intake points (A=air) (F=fumes)
2 - Flue safety pressure switch
3 - Fan
4– System drain valve
5 - Gearmotor for 3-way valve
6 - Gas valve
7 - System filling valve
8 - Automatic air vent
9 - Sealed chamber
10 - Expansion vessel
11 - Adjustment and limit NTC probe
12 - Combustion chamber
13 - Overheat. safety thermostat
14 - Circulator
15- 3-bar safety valve
13- Pump pressure switch
17- 3-way valve
18- Adjustable automatic by-pass
19- Positive signal pressure point
20- Negative signal pressure point
21 - Draught diverter
22 - Primary exchanger
23 - Ignition and detection electrodes
24 - Burner
CONTROL PANEL
1 - Green heating operating indicator
2 - Heating temperature selector
3 - D.h.w. temperature selector
4 - Green d.h.w. operation indicator
5 - 0/SUMMER and CAR/WINTER switch
6 - Boiler pressure gauge
7 - Reset
8 - Temp./diagnostics display
9 - Burner operation indicator

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EOLO SUPERIOR PLUS
PLUS STORAGE TANK MAIN COMPONENTS
Storage tank 80 l Storage tank 105 l
Storage tank 120 l
1 - D.h.w. NTC sensor
2 - D.h.w. drain valve
3 - Thermometer
4 - D.h.w. expansion vessel
5 - Coil
6 - Anode
CONTROL PANEL
1 - Storage-tank ON-OFF
thermostat setting cap
2 - Storage tank thermometer

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EOLO SUPERIOR PLUS
HYDRAULIC CIRCUIT
1 - Gas valve
2 - 3-way valve gearmotor
3 – Electric 3-way valve
4 - Burner
5 - Primary exchanger
6 - Sealed chamber
7 - Draught diverter
8 - Fan fan
9 - Flue safety pressure switch
10- NTC limit and adjust. sensor
11- Air vent valve
12- Expansion vessel
13- Circulator
14- Overheat. safety thermostat
15- Pump pressure switch
16- 3-bar safety valve
17- Pump pressure meter
18- One way valve
19- Adjustable bypass
20- System drain valve
21- System filling valve
22- D.h.w. inlet cock.
23- D.h.w. expansion vessel
24- 8-bar safety valve
25- Storage tank
26- Anode
27- D.h.w. NTC sensor
28- Storage tank coil
RI - System return
MI - System flow
RB - Storage tank return
MB - Storage tank flow
G - Gas supply
U - Hot d.h.w. outlet
E - Cold d.h.w. inlet
RC - Re-circulation (optional)
PRIMARY CIRCUIT (BOILER CIRCUIT)
The primary circuit, with relevant control and safety devices, operates every time there is a central
heating or d.h.w. request.
- OPERATION
The heat contained in the combustion products is absorbed by the copper blades of the water-gas
exchanger (5), which in turn transfers this to the water circulating inside by means of the boiler pump
(13).
When the boiler is working for water heating only, the water flows directly into the system, while it can
be deviated inside the storage tank coil (28) if combined with a PLUS unit.
This depends on the position of the 3-way electric valve (3) which, depending on the type of request,
allows the water to flow through the delivery pipe (M) and return pipe (R) system or causes its deviation
towards the storage tank coil (28).

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EOLO SUPERIOR PLUS
- CIRCULATOR
This operates on the primary circuit return and is
located on the brass header assembly.
It is connected to the monobloc and exchanger by
means of threaded connecting pieces, while the
primary exchanger and expansion vessel are
connected by coupling pipes (2) with O.R. seal (3),
fastened with special forks (1).
.
- HEAD - FLOW GRAPH
The curve that represents the relation between the flow rate and the available head depends on
system bypass adjustment which, depending on its position, gives the system greater or less head.
The graph below refers to the pump operating at top speed with:
- A = Bypass disconnected (screw fully tightened)
- B = Standard bypass adjustment (screw tightened by 4.5 turns with respect to fully-tightened
position)
- C = Bypass open (screw fully loose)
- PRIMARY EXCHANGER
This is a water-gas blade type exchanger with
copper pipes and fins at the outlet of which an
NTC heating probe (5) is located.
The four pipes passing through the exchanger are
connected in parallel (1) two by two, to reduce
flow resistance to the utmost and provide a greater
available head.
It is connected to the pump flow and to the
primary circuit flow by means of coupling pipes
(2) with O.R. seal (4).
These are secured by means of special forks (3).

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EOLO SUPERIOR PLUS
- SAFETY DEVICES AND CONTROLS
System bypass (3)
This ensures water circulation in the primary circuit
(between flow and return) even when this is
prevented by the high resistance of the system.
It is mounted on a monobloc and can be adjusted by
means of a screw accessible from the bottom part of
the valve plate.
Pump pressure meter (1)
This detects the difference in pressure at pump
extremities.
Its housing is in the monobloc and is coupled to a
micro-switch that prevents burner operation in the
event of pump blockage or no water in the boiler
circuit.
Prevents primary exchanger overheating.
Automatic air vent (4)
Automatically expels any gaseous substances in
the boiler circuit.
Secured to the water side of the expansion vessel.
3-bar safety valve (2)
Fitted to the front part of the 3-way monobloc and
prevents safety pressure (3 bar) being exceeded in
the circuit.
When this trips, water exits from the flow pipe.
One way valve (7)
During domestic hot water production, this
prevents natural circulation occurring in the
central heating circuit.
Expansion vessel (5)
Compensates changes in volume following
heating of water and permits reducing pressure
changes.
It is fitted in the rear of the appliance and is
connected to the pump by means of the coupling
pipe (6).
It has a capacity of 8 l and a pre-load pressure of
0.8 bar.

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EOLO SUPERIOR PLUS
HYDRAULIC CIRCUIT
- SECONDARY CIRCUIT (D.H.W. CIRCUIT)
The domestic hot water circuit is engaged every time the water contained in the storage tank and
measured by means of the d.h.w. NTC sensor (4) has to be restored to the desired temperature.
- OPERATION
Following a d.h.w. request, the modulation board starts the boiler pump (1) and powers the motor of the
electric 3-way valve (2).
The consequent movement of the valve to d.h.w. position (see 3-way electric valve), closes the system
return pipe (RI) and, at the same time, opens the return pipe of the storage tank coil (RB).
This way, circulation is allowed in the coil (3) which, through its walls, enables the cold domestic water
to absorb the heat contained in the primary circuit water.
In this phase, the central heating function is disconnected as the production of d.h.w. has priority.
- HEAD - FLOW TO STORAGE TANK GRAPH
To ensure the heat exchange of the
entire nominal heat output of the boiler,
the hydraulic connection to the PLUS
unit (optional) must have flow
resistances below those shown on the
graph alongside.

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EOLO SUPERIOR PLUS
- STORAGE TANK UNIT (optional)
The PLUS storage tank units ( 80 l, 105 l and 120
l) consist of a coil storage tank unit insulated with
polystyrene supplied complete with covering and
instrument panel.
The storage tank is made entirely of AISI 316 L
stainless steel and consists of an outer jacket
enclosed in the top part by a flange secured by 12
screws.
Inside is a coil (two in the case of the 120 l model)
consisting of a concentric-spiral shaped stainless-
steel pipe that develops in the bottom part of the
storage tank and through the walls of which the
heat exchange occurs between the hot water of the
primary circuit and the water in the storage tank.
This ensures the water in the storage tank is always
at a constant temperature and, in the case of a water
request, results in the instantaneous production of
hot water.
If necessary, the coil can be removed from the
storage tank after taking off the upper inspection
flange.
The storage tank unit is complete with a series of
devices that not only ensure proper operation, but
also protect its integrity:
Anode (6)
This is fitted in the storage tank and protects this
against the effects of galvanic currents.
It is screwed onto the upper flange.
Polyphosphate metering unit (optional)
Prevents limestone deposits on the coil walls.
The kit is fitted at the cold domestic water inlet.
Safety valve unit (14)
This assembly is located in the top part of the storage
unit near the cold domestic water inlet.
Besides an 8-bar valve (“7” d.h.w. circ.) which
prevents safety pressure being exceeded inside the
storage tank, it comprises:
- a flow limiting device - 12 l/min (80 l and 105 l
versions only)
- an one way valve (“8” d.h.w. circ.) to prevent the
increase in pressure resulting from d.h.w heating
causing a return towards the cold water system.
ON-OFF thermostat kit (12) (optional)
Adapts operation of the storage tank unit to systems
with ON-OFF type temperature control.
It consists of a thermostat, the bulb of which is fitted
in place of the NTC sensor which is electrically
connected to the terminal board of the storage tank
instrument panel.
Adjustment is made from the control panel after
having removed the special plate (13).
Re-circulation kit (11) (optional)
Permits connecting the pipes of any d.h.w. re-
circulation system.
It consists of a pipe that is fitted in the storage tank
after removing the anode (7) and the relevant cap.
When the kit is installed, the anode (7) must be
screwed onto the end of the pipe.
D.h.w. drainage valve (10)
This is a brass cap complete with hose connection
located (screwed) onto the outer wall of the
storage tank by means of which the water inside
the tank can be drained off.
NTC Storage tank sensor (NB) (4)
Enables the modulation board to determine the
temperature of the water in the storage tank.
It is fitted in a bulb holder in contact with the outer
wall of the storage tank.
D.h.w. expansion vessel (9)
Compensates changes in volume caused by the heating
of the water in the storage tank.
The 80 l and 105 l versions have a capacity of 4 l,
while the 120 l version holds 5 l.
PLUS 80 l UNIT

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EOLO SUPERIOR PLUS
- MOTORISED 3-WAY VALVE
This is a 3-way electric valve operating on the return pipe of the primary circuit that permits,
according to the type of request (d.h.w. or central heating), running boiler water into the central
heating system or into the storage tank coil.
This depends on the position of the shutter (3) which impedes transit towards the system and at the
same time permits this towards the storage tank (d.h.w. position) or vice versa (central- heating
position).
Movement of the shutter (3) in both positions is achieved by energising the motor (1).
Operation
When the central heating or d.h.w. position has
to be achieved, the motor (1) is operated by the
modulation board.
Operation of the motor, whose number of revs
is reduced by a special system of gears,
involves rotation of a disc (6) fastened
eccentrically on the shaft of the motor.
Movement of this disc causes the movement of
a special coupling (5) which, at each 180°
rotation, compresses (d.h.w. position) or
releases (heating position) the contrast spring
of the shutter (4).
Hydraulic achievement of the required position
causes, alternately, the opening of a limit
switch (2) and the closing of the other.
This permits de-energising the motor and
locking this in the achieved position, and
enabling motor operation only when a different
request is made (d.h.w. or central- heating
signal).

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EOLO SUPERIOR PLUS
GAS CIRCUIT
- OPERATION (See EOLO Maior @)
- MODULATING GAS VALVE (See EOLO Maior @)
- BURNER (See EOLO Maior @)
GAS ADJUSTMENTS
Max and minimum gas pressure
adjustments can be made by means of
the gas valve respecting the values
shown on the tables relating to each
boiler for the type of corresponding gas.
Measurement is made using a pressure
gauge connected to the outlet of the gas
valve (6) and to the positive pressure
point located on the upper part of the
sealed chamber (see illustration
alongside),
Then proceed as follows depending on
the gas valve fitted to the boiler.
- VALVE VK 4105 M (with yellow protection cap)
Minimum pressure adjustment
- After interrupting the power supply
to the modulation coil (*), turn screw
"3" clockwise to increase pressure to
the burner and anticlockwise to
decrease it.
Maximum pressure adjustment
(operation to be performed after
minimum pressure adjustment)
- Do a d.h.w.request (open a tap) and
setting the temperature selector at
maximum.
Turn nut ”4” clockwise to increase
pressure to the burner and
anticlockwise to decrease pressure.
1) Modulation coil 5) Yellow protection cap
2) Coil pin 6) Gas valve outlet press. point
3) Min. output adjust. screw 7) Valve inlet press. point
4) Max. output adjust. screw 8) Air press. point hose connector

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EOLO SUPERIOR PLUS
- VALVE VK 4105 M-M with integrated flanges (with transparent protection cap)
Maximum pressure adjustment
- Do a d.h.w.request (open a tap) and
setting the temperature selector at
maximum.
Turn nut ”3” clockwise to increase pressure
to the burner and anticlockwise to decrease
pressure
Minimum pressure adjustment
(operation to be performed after maximum
pressure adjustment)
- After interrupting the power supply to the
modulation coil (*), turn screw "4"
clockwise to increase pressure to the burner
and anticlockwise to decrease it.
1) Modulation coil 5) Transparent protection cap
2) Coil pin 6) Gas valve outlet press. point
3) Min. output adjust. screw 7) Valve inlet press. point
4) Max output adjust screw 8) Air press. point hose
connector
- VALVE SIT 845
Maximum pressure adjustment
- Do a d.h.w. request after setting the
temperature switch at maximum.
Turn nut “3” clockwise to increase the
burner pressure and anticlockwise to
decrease it.
Minimum pressure adjustment
(to be done after maximum pressure
adjustment)
- After interrupting power to the
modulation coil, turn screw “2”
clockwise to increase burner pressure
and anticlockwise to decrease it.
1) Modulation coil
2) Minimum output set screw
3) Maximum output set screw
4) Gas valve outlet pressure point
5) Gas valve inlet pressure point
6) Protection cap
- CHANGING TYPE OF GAS
Adaptation to a type of gas different to that for which the boilers are intended, can be done by using the
special kits (natural gas or LPG).
The changeover consists in replacing the burner nozzles and in moving to the modulation board of the
“NATURAL GAS- LPG” (CM3) bridge.
The minimum and maximum pressures are then set on the gas valve in the way described above.
Adjustment of the minimum and maximum output during the heating phase and of burner ignition
pressure (see table below) can be done by means of the respective trimmers mounted on the modulation
board (see modulation board operation).
Soft ignition values in mbar (mm H2O)
Natural Gas LPG
EOLO 24 Superior Plus 25 60

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EOLO SUPERIOR PLUS
FLUE CIRCUIT
- OPERATION (See EOLO Maior @)
- FAN (See EOLO Maior @)
- FLUE PRESSURE SWITCH (See EOLO Maior @)
- AIR/FLUE SAMPLING SUMPS (See EOLO Maior @)
- FLUE PRESSURE SWITCH SIGNAL PRESSURE POINT (See EOLO Maior @)
EXTRACTION AND EXHAUST SYSTEMS
(see extraction and exhaust end instructions )
- EXHAUST (See EOLO Maior @)
- EXTRACTION (See EOLO Maior @)
- EXTRACTION-EXHAUST KIT
Coupling type horizontal concentric kit 60 / 100 (See EOLO Maior @)
Coupling type horizontal concentric kit 80 / 125 (See EOLO Maior @)
Coupling type vertical concentric kit 60 / 100 (See EOLO Maior @)
Coupling type vertical concentric kit 80 / 125 (See EOLO Maior @)
Coupling type separator kit 80 / 80 (See EOLO Maior @)
Insulated coupling type separator kit 80 / 80 (See EOLO Maior @)

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EOLO SUPERIOR PLUS
ELECTRICAL CIRCUIT
CAR Remote control
CZ Control xone unitt
DL1 Central heating operation LED
DL2 D.h.w. operation LED
DL3 Flame LED
E1/E2 Ignition electrodes
E3 Detection electrode
FFuse
IG Main switch
MOD Modulation coil
MP Circulator
MV Fan
NB D.h.w. NTC sensor
NE External sensor (optional)
NR Central heating NTC sensor
P1 Room thermostat bridge
PU1 Reset button
SP Pump pressure switch
SV Flue pressure switch
TA Room thermostat
TS Overheat. safety thermostat
UB Storage tank unit
VD Electric three-way valve
V/G Gas valve
The electric circuit is interlocked with a microprocessor electronic board that controls boiler functions.
The control and safety devices work in part at mains voltage and in part at low voltage.
230 V AC CIRCUIT
SAFETY DEVICES AND CONTROLS
Detection electrode (E3) This detects ignition of the burner by whose flame it is invested.
It is connected to the detection circuit of the ignition unit.
Fuse This interrupts power to the circuit when amp draw is over 3.15 A.
It is fitted on the modulation board.
Fuse
3.15 A 250 V
Depending on position, this allows:
Main switch
(IG)
0 - circuit not powered
- d.h.w. and CAR function (optional)
-d.h.w. and central heating function.
3-position switch
Overheat. safety device
(TS)
When the safety temperature (100 ºC) is exceeded, this interrupts power
to the main coils of the gas valve.
It is positioned on the flow pipe at the primary exchanger outlet.
Clicson double-
contact
thermostat

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EOLO SUPERIOR PLUS
LOADS
3-way electric valve
(VD)
Deviates the flow of water of the primary circuit from the heating circuit to the boiler coil
and vice versa.
It is powered by the modulation card.
Circulator
(MP)
Permits circulation of water in the primary circuit.
This is powered by the modulation board whenever there is a demand for d.h.w.,
heating or antifreeze.
Fan (MV) Ensures the flow of air inside the sealed combustion chamber and the exit of fumes
produced by combustion.
Powered by the modulation board.
Gas valve (VG)
(main coils)
This is powered by the ignition control unit when the burner has to be ignited.
Permits flow of gas to the burner.
Ignition control unit
(IGN. CARD)
Controlled by the modulation board when the burner has to be ignited.
Controls the devices needed for ignition (gas valve, ignition electrodes) and flame detection
(ionisation electrode).
Ignition electrodes
(E1 - E2) These provoke an electric spark that ignites the air/gas mix.
They are controlled by the control unit ignition transformer (IGN. CARD)
Modulation card This is powered when the main switch (IG) is positioned in (summer or CAR) or
(winter) (see modulation board operation).
LOW-VOLTAGE CIRCUIT
SAFETY DEVICES AND CONTROLS
Central-heating sensor
(NR)
Allows the modulation board to detect the temperature of the primary
circuit water flow.
If this sensor stops working, burner operation stops both in central-
heating and d.h.w. modes.
It is positioned at the outlet of the main exchanger.
Sensor NTC
10 kohm 25 ºC
Control zone unit (CZ)
(external optional)
Permits boiler operation with 3 area valves /external pumps controlled
by respective room thermostats.
Zone 1 is controlled (times/temperatures) by means of the CAR (if
fitted).
See control unit
zone operation
Domestic hot water sensor
(NB)
This enables the modulation board to detect the temperature of the hot
water in the storage tank.
Its failure stops burner operation in domestic hot water phase.
It is fitted in a bulb holder in contact with the wall of any connected
external storage tank.
Sensor NTC
10 kohm 25 ºC
External sensor (NE)
(external optional) Detects external temperature and enables the modulation board to
change the system flow temperature according to outside temperature. Sensor PTC
1 kohm 25 ºC
Flue pressure switch
(SV)
This acts on the modulation board and enables burner operation when
fume expulsion occurs correctly.
If this is closed with the fan off, the ignition cycle will not start.
2-position switch

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EOLO SUPERIOR PLUS
Pump pressure switch
(SP) This acts on the modulation board and permits interrupting power to
the control unit in the event of there being no circulation in the boiler
circuit.
Double-contact
switch
Remote control (CAR)
(external optional)
Permits remote control of boiler (iSUM/WINT switch, temperature
adjustment and indication, alarm display, reset, etc.) and acts as a
weekly chrono-thermostat.
Together with the external sensor (NE), allows the modulation board to
change the system flow temperature according to need.
See Remote
Friend Control
operation (CAR)
Room thermostat (TA)
(external optional)
This enables operation in central heating phase when the room
temperature is below that required.
In case of CAR installation, the room thermostat must be disconnected
without resetting the pre-existing bridge P1.
Double clean-
contact switch
LOADS
Display card This displays burner operation (orange LED), operation in d.h.w. phase (green LED) and in
central-heating or antifreeze phase (green LED) on the control panel.
By means of a monitor, it indicates the temperature of the boiler, the temperatures set for
d.h.w. and central-heating and the error codes (see modulation board operation).
Modulation coil (MOD) This is powered by the modulation board with variable direct current.
It permits changing gas pressure to the burner.

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EOLO SUPERIOR PLUS
ELECTRICAL CIRCUIT
CENTRAL-HEATING PHASE
(*) only on the Honeywell VK 4105 gas valve, the main coils are powered at mains voltage by means of a
diode bridge (fitted in the connection connector)
When the mainr switch (IG) is in WINTER position, it powers the modulation card and enables operation in
central heating mode.
When the room thermostat contact (TA) is closed, the low-voltage circuit starts the pump (MP) by closing the
contact of relay RP.
The circulation of water causes the pump pressure switch (SP) to close and, because this is connected in series
with the NC contact of the flue pressure switch (SV), the coil of relay K5 is energised.
Meanwhile, the adjustment circuit causes the deviation of the relay contact R3V.
This way, the motor (M) is powered of the 3-way valve (VD), which continues to operate until the limit
switch "A" opens once the central heating position has been reached.
If the temperature read by the NTC heating sensor (NR) is below that set on the control panel with the heating
potentiometer, the low-voltage circuit excites the relay K5 and starts the fan (MV) commanding the relay RV.
The consequent deviation of the flue pressure switch (SV) powers the relay RT the contact of which, on
closing, enables the control unit (IGN. CARD) to start the ignition cycle, commanding first of all the ignition
electrodes (E1-E2) and then, with the consensus of the overheating thermostat (TS), both the main coils of the
gas valve (V/G).
Ignition of the burner is detected by the control unit (IGN. CARD) by means of the ionisation electrode (E3).
Operation with Remote Friend Control
The main switch (IG) in SUMMER 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 setting above that read by the
central-heating sensor NR requested by the time programmer, room temperature adjustment above that
read), the board powers pump MP through relay RP contact.
Burner ignition then 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 seconds., which can be reduced to 30
seconds by intervening on the special bridge (J1) (see modulation card operation).

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EOLO SUPERIOR PLUS
ELECTRICAL CIRCUIT
D.H.W. PHASE
(*)only on the Honeywell VK 4105 gas valve, the main coils are powered at mains voltage by means of a
diode bridge (fitted in the connection connector)
Operation
When the main switch (IG) is in SUMMER or WINTER position, it powers the modulation board and
enables operation in d.h.w. mode.
When the temperature read by NTC d.h.w. sensor (NB) is below that set on the control panel (or on the
CAR if fitted), the adjustment circuit starts the pump (MP) by means of the contact of relay RP.
The circulation of water causes the pump pressure switch (SP) to close and, because this is connected in
series with the NC contact of the fume pressure switch (SV), the coil of relay K5 is energised.
Meanwhile, the adjustment circuit causes the deviation of the relay contact R3V.
This way, the motor (M) is powered of the 3-way valve (VD), which continues to operate until the limit
switch "N" opens once the d.h.w. position has been reached.
The low-voltage circuit excites the relay K5 and starts the fan (MV) commanding the relay RV.
The consequent deviation of the flue pressure switch (SV) powers the relay RT the contact of which, on
closing, enables the control unit (IGN. CARD) to start the ignition cycle, commanding first of all the
ignition electrodes (E1-E2) and then, with the consensus of the overheating thermostat (TS), both the
main coils of the gas valve (V/G).
Ignition of the burner is detected by the control unit (IGN. CARD) by means of the ionisation electrode
(E3).

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EOLO SUPERIOR PLUS
MODULATION CARD
The boiler is equipped with a microprocessor-controlled electronic board used on both the models with 3-way
electric valve (Zeus Superior, Eolo Superior Plus) and on the models with central-heating and d.h.w. pumps
(Hercules).
The different type of operation is obtained by adjusting diode D9 (diode engaged = electric 3-way valve,
diode disengaged = double pump).
The board is connected to a terminal board (DISPLAY CARD) which, by means of LEDs and a display panel,
indicates the state of operation of the appliance.
The board is powered with master switch (IG) in position (summer) or (winter).
Central-heating request with room thermostat
With the main switch in WINTER position and the contact of the room thermostat (TA) closed, the low-
voltage circuit starts the circulator (MP) by means of relay “RP” and powers the motor (M) of the 3-way valve
(VD) through the contact of relay “R3V”.
The circulation of water results in the closing of the pump pressure switch (SP) which, because it is connected
in series to the NC contact of the flue pressure switch (SV) powers the coil of relay “K5”.
If the temperature detected by means of NTC central heating sensor (NR) is below that set on the control
panel by means of the central heating potentiometer (RISC), the adjustment circuit excites relay “K5” and
starts the fan (MV) controlled by relay “RV”.
The consequent deviation of the contact of the fume pressure switch (SV) results in relay “RT” being powered
and the relevant contact closing.
This powers the control unit (IGN. CARD) and starts the ignition cycle.
During the ignition phase, the power to the modulation coil is restricted by the adjustment made with the slow
ignition trimmer (POT ACC.).
Once the flame has been detected (signal from control unit), the signal to the coil (MOD) is changed in a
manner directly proportionate to the difference between the temperature set with the central-heating
potentiometer (RISC) and that detected by means of the NTC central-heating sensor (NR) and, if necessary,
reaches maximum set value in 50 seconds (maximum central-heating output).
When the set value is exceeded, the contact of relay “RT” is opened with consequent switch-off of the burner.
Re-ignition of the burner for the same request remains inhibited for 180 s / 30 s.
Central-heating request with Remote Friend Control
If the conditions detected by the remote control (CAR) require ignition in central-heating phase (SUM/WINT
switch of CAR in WINTER position, time programmer request, room temperature setting above that found),
the low-voltage circuit starts the circulator (MP) by means of relay RP and powers the motor (M) of the 3-way
valve (VD) by means of the contact of relay “R3V”.

Technical documentation Technical documentation
STESP ed 02/02 20
EOLO SUPERIOR PLUS
The circulation of the water causes the pump pressure switch (SP) to close and because this is connected
in series to the NC contact of the flue pressure switch (SV) powers the coil of relay “K5”.
If the temperature detected by means of NTC central-heating sensor (NR) is below that set by means of
the central heating potentiometer of the remote control (CAR), the adjustment circuit excites relay “K5”
and starts the fan (MV) controlled by relay “RV”.
The consequent deviation of the contact of the flue pressure switch (SV) results in relay “RT” being
powered and the relevant contact closing.
This powers the control unit (IGN. CARD) and starts the ignition cycle, which continues in the same
way as the central-heating request with room thermostat.
Once the flame has been detected, the signal to the modulation coil is changed in a manner directly
proportionate to the difference between the boiler and room temperatures set and detected and, if
necessary, reaches maximum set value in 50 seconds (maximum central-heating output).
When the set value is exceeded, the contact of relay “RT” is opened with consequent switch-off of the
burner.
Re-ignition of the burner for the same request remains inhibited for 180 s / 30 s.
Domestic hot water request
If the temperature read by the NTC sensor on the storage tank (NB) is below that set by means of the
d.h.w. potentiometer (D.H.W.), the low-voltage circuit starts the pump (MP) by means of relay “RP” and
powers the motor (M) of the 3-way valve (VD) through contact of relay “R3V”.
Following consequent closing of pump (SP) pressure switch burner ignition proceeds in the same way as
for central-heating phase.
Flame modulation occurs with reference to the flow temperature read by the central-heating sensor (NR)
which is changed according to the difference between the temperature set by means of the d.h.w.
potentiometer (D.H.W.) and that measured by the d.h.w. sensor (NB).
When the temperature measured by the d.h.w. sensor (NB) exceeds that requested, the contact of relay
RT is opened and after post-operation times also the contacts of relays “RP” (pump) and “RV” (fan).
When the temperature drops again, the relays are once again powered to start the new ignition cycle.
If, during operation, the heating sensor. (NR) measures a flow temperature higher than 87 ºC, the contact
of relay RT is opened. This is closed again just as soon as the temperature drops to 75 ºC.
Central-heating antifreeze request
With the main switch (IG) in SUMMER or WINTER position, if the temperature read by the NTC
central-heating sensor falls below 4 ºC, the board allows ignition in central-heating mode and keeps the
boiler operating with the burner at minimum output until a boiler temperature of 43°C is reached.
Domestic hot water request
With the main switch (IG) in SUMMER or WINTER position, if the temperature read by the NTC
d.h.w. sensor (NB) falls below 4 ºC, the board allows ignition in d.h.w. mode and keeps the boiler
operating with the burner at minimum output until the d.h.w. (NB) sensor reads a temperature of 8°C.
During operation, the water in the primary circuit remains below 42°C because when such temperature
is reached, the board switches off the burner.
“Chimneysweep” request
When the reset button (PU1) is pressed for at least 10 seconds, as soon as this is released, the board
gives the signal for boiler ignition and keeps this operating in central-heating mode at max heating
output for 15 minutes.
In this phase, only the limit thermostat function is operative (90 ºC) performed by the central-heating
sensor.
The function is only engaged if there are no requests under way for central-heating, domestic hot water
or antifreeze and it is indicated by means of code "7" on the display panel and by the flashing of central-
heating (DL1) and d.h.w. (DL2) LEDs.
It can be interrupted by cutting power to the circuit.