Immergas EOLO STAR 24 3 E Guide

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NIKE Star 24 3 E
Small wall-mounted open chamber, conventional
ue instant boiler.
NIKE Star 24 3 E
NIKE Star 24 3 E is a wall-mounted, open combustion cham-
ber, conventional ue generator for the heating and production
of domestic hot water.
e boiler distinguishes itself for its extremely small dimensions
H=751 mm, L=440 mm, D=240 mm) and useful heat output
of 23.6 kW (20,296 kcal/h).
Adjustment and control of the appliance (burner ignition,
temperature adjustment, ame modulation and diagnostics), are
entrusted to an electronic P.C.B. with microprocessor that by
means of a digital interface complete with display and buttons,
General features.
allows the visualisation and adjustment of the functioning
parameters.
e hydraulic circuit is equipped with a bithermal water-gas
copper heat exchanger for the production of hot water for
central heating and domestic hot water use, an automatic
by-pass of the system and a ow switch for the cut-o of DW
withdrawal.
e appliance has IPX4D electrical insulation rating: this
means that the boiler is protected against jets of water and
high humidity levels.
Key:
G - Gas supply
AC - Domestic hot water outlet
AF - Domestic cold water inlet
R - System return
M - System ow
V - Power supply connection
Main dimensions and connections.
Height (mm) Width (mm) Depth (mm)
751 440 240
CONNECTIONS
GAS DOMESTIC
HOT WATER SYSTEM
GAC AF R M
3/4” 1/2” 1/2” 3/4” 3/4”

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Key:
1 - System lling valve
2 - Domestic hot water probe
3 - Gas valve
4 - Domestic hot water ow switch
5 - Combustion chamber
6 - Flue hood
7 - Flue safety thermostat
8 - Safety thermostat
9 - Flow probe
10 - System expansion vessel
Main components.
11 - Air vent valve
12 - System pressure switch
13 - Boiler pump
14 - Manifold
15 - 3 bar safety valve
16 - System draining valve
17 - Rapid heat exchanger
18 - Ignition and detection electrodes
19 - Burner

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Key:
1 - Reset button
2 - Stand-by/summer/winter button
3 - Button (+) to increase
the domestic hot water temperature
4 - Button (-) to reduce
the domestic hot water temperature
5 - Button(+) to increase the system water temperature
6 - Button (-) to reduce the system water temperature
7 - Boiler manometer
8 - Domestic hot water functioning
Control panel.
9 - Temperatures and error code display
10 - Unit of measurement
11 - Central heating functioning
12 - Winter
13 - Summer
14 - Power distributed
15 - Flame presence

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e central heating circuit, with relative control and safety
devices, is started every time there is a central heating
request.
Operation.
e heat contained in the combustion products is absorbed
by the copper blades of the water-air heat exchanger (7) which
then gives the heat up to the water made to circulate inside
the boiler pump.
e hot water is introduced directly into the central heating
system through ow (M) and return (R) pipes.
Key:
1 - Domestic hot water probe
2 - Domestic hot water ow switch
3 - Gas valve
4 - Flow limiter
5 - System draining valve
6 - Burner
7 - Rapid heat exchanger
8 - Flue hood
9 - Flue safety thermostat
10 - System expansion vessel
11 - Flow probe
12 - Safety thermostat
13 - Air vent valve
14 - Boiler pump
15 - System pressure switch
16 - Automatic by-pass
17 - 3 bar safety valve
18 - System lling valve
G - Gas supply
AC - Domestic hot water outlet
AF - Domestic cold water inlet
R - System return
M - System ow
Hydraulic circuit.
Primary circuit (Boiler Circuit).
e hot water used for central heating and domestic hot
water is produced thanks to two distinct circuits that are
aected according to necessity.

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3
2
3
2
1
4
Boiler pump (1).
Operates on the primary circuit return. It is part of the pump
body unit realised in composite material.
ere is a seat where the automatic air vent valve (2) is housed
with O-ring sealing.
To remove the air vent valve from the pump body, turn the
valve by a quarter turn in an anti-clockwise direction.
Head ow rate graphics.
In central heating mode the generator guarantees available head
to the system depending on the ow rate, which s represented
by the following graphics that show the characteristic curve.
Head (m H2O)
A = Head available to the plant.
Portata (l/h)
Head (kPa)
A
Primary heat exchanger.
It is a bithermal water-air blade-type heat exchanger with
copper pipes and ns (N° 72 ns) that produce hot water for
central heating and domestic hot water.
It therefore operates directly in both circuits (DHW or CH)
to which it is connected directly by push tting pipes (2) with
O-ring sealing and blocked using relevant clips (3).
e 6 oval pipes of which it is formed and through which
CH circuit water runs, contain just as many "cross-wise"
pipes that are aected by the direct passage of the DHW (see
gure below).
ese pipes are hydraulically connected in parallel three by
three onto the CH circuit and in series in the DHW circuit.
At the heat exchanger outlet (central heating ow) nd the
NTC ow probe (1) and the over-heating safety thermostat
(4).
Domestic
cold water
inlet Domestic
hot water
outlet
Domestic
hot water
outlet
System
ow
Return
system
Heat exchanger pipe section
System central
heating circuit DHW circuit
1
2
Flow rate (l/h)

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Safety devices and controls.
System automatic by-pass (3).
Guarantees circulation in the CH circuit also when the high
resistance of the system does not allow it.
It operates between the ow and the return of the CH circuit
and is inserted inside the by-pass tting (4) that connects the
pump unit (2) to the ow.
System ling unit (7).
It is a cock positioned between the boiler circuit and the dome-
stic cold water inlet that allows to pressurise the CH system.
e lling unit is connected to the DHW ow switch (6) by
a threaded tting and is connected to the pump unit (2) by
O-ring gaskets.
System pressure switch (5).
Detects the pressure inside the primary circuit.
Its seat is on the pump body (2) and is coupled to a micro
switch that prevents functioning of the burner when the pres-
sure detected is below 0.3 bar.
Prevents overheating of the primary heat exchanger.
Automatic air vent valve (1).
Allows the automatic expulsion of the gaseous substances that
may be present in the boiler circuit.
It is mounted on the pump directly on the body (2).
3 bar safety valve (5).
Prevents the safety pressure in the primary circuit from being
exceeded (3 bar).
It is engaged into the front part of the pump body (2) and is
xed using a clip.
Its intervention causes water to escape from the boiler re-
turn.
System expansion vessel (8).
It compensates the volume variation consequent to heating
the water, thus limiting the pressure variations.
It has a capacity of 6 litres (useful 4.2 litres) and a factory/set
pressure of 1.0 bar.
It is positioned on the right side of the boiler at the side of
the sealed chamber and is connected to the pump body (2) by
means of a copper pipe.
8
4
1
2
3
5
6
7
2
5

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Secondary circuit (Domestic Hot water Circuit).
Operation.
A DHW withdrawal leads to the passage of cold water inside
the ow switch (4) and the consequent closure of the electric
contact coupled to it (see electric circuit).
Following this, the adjustment circuit starts the DHW priority
functioning mode, which leads to burner ignition (3) and,
when a CH request is in progress, switch o of the boiler
pump.
In this way, the heat contained in the combustion products is
absorbed by the copper blades of the bithermal heat exchanger
(2) is given up to the water in the central heating circuit which,
then transmits it to the domestic cold water that ows through
the “cross-wise” DHW pipes (1).
Domestic hot water ow switch.
With respect to a withdrawal of DHW with a ow rate of at
least 1.7 l/min and a dynamic pressure of 0.3 bar, the ow
switch (2) enables the boiler functioning in DHW mode.
is takes place by means of a magnet which, lifting when
it is hit by the ow of domestic cold water, approaches an
electric contact (reed relay) and causes shifting due to the
magnetic eect.
e closure of the contact, which is positioned out of the pipe
where the water passes, allows the integrated P.C.B. to start
the priority DHW functioning mode.
It is made up from two parts (one in brass and one in plastic)
that are coupled and blocked by a pin.
A G1/4" thread is present on the body to which the system
lling unit is connected (3).
A 7.1 l/min ow limiter is inserted at the outlet of the ow
switch (1) (at 2 bar).
Bithermal heat exchanger
(see central heating circuit).
N.B.: to preserve the duration and eciency of the heat exchanger
it is recommended to install the “polyphosphate dispenser” kit in
the presence of water whose characteristics can give rise to scale
deposits (for example, the kit is recommended when water hardness
is higher than 25 French degrees).
1
2
3
Domestic cold
water inlet

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e circuit is composed of an atmospheric burner and a mo-
dulating gas valve, which respectively allow the combustion
of the gas and the adjustment of its ow rate.
Operating.
e electric power supply of the main coils (3) causes the
opening of both internal shutters of the valve, thus allowing
the passage of gas towards the burner. e outlet ow rate/
pressure is then adjusted by acting on the gas valve stabiliser
by means of the modulation coil (1).
e fuel is injected, by means of the burner nozzles (6), into
the horizontal Venturi pipes (ramps). Here, an optimal air-gas
mixture is obtained that is ignited by the spark of the ignition
electrode (4).
Modulating gas valve (VK 4105 M).
e gas valve is equipped with two main coils (3) and a mo-
dulation coil (1) controlled by the integrated P.C.B.
e maximum and minimum outlet pressure values are cali-
brated on the valve (see gas adjustments).
Main electric coils (3).
ey are two ON-OFF coils that are powered (230 V AC) by
the integrated P.C.B. when burner ignition is necessary.
ey are connected in series and powered at network voltage
rectied by means of a diodes jumper (U1) positioned inside
connector (2) (see wiring diagram).
Gas circuit.
Modulation coil (1).
It is a low voltage coil that is controlled by the integrated
P.C.B.
It acts on the gas valve stabiliser and allows the variation of
the outlet pressure proportionally to the direct current that
passes through it.
Modulating gas valve (SIT 845).
e gas valve is equipped with two main coils (3) and a mo-
dulation coil (1) controlled by the integrated P.C.B.
e maximum and minimum outlet pressure values are cali-
brated on the valve (see gas adjustments).
Main electric coils (3).
ey are two ON-OFF coils that are powered (230 V AC) by
the integrated P.C.B. when burner ignition is necessary.
ey are connected electrically in parallel and powered from
the mains voltage via a relevant connector (2).
Modulation coil (1).
It is a low voltage coil that is controlled by the integrated.
COIL POWER SUPPLY RESISTANCE
EV1 + EV2 230 V AC EV1 = 2,85 kΩ
EV2 = 1,35 kΩ
Modulation coil
(Blue)
250mA DC (G20)
320mA DC (L.P.G.) 28 Ω
Reference values with boiler at maximum power
1
3
2
EV1
EV2 EV1
+
EV2 =
230V
Connector viewed
from the gas valve
Modulation
Coil



Modulation
Coil
Connector viewed
from the gas valve
EV1
EV2
Common

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Height to respect:
H min = 2,5 mm
H max = 4 mm
Nominal position on the
third pair of slots
It acts on the gas valve stabiliser and allows the variation of
the outlet pressure proportionally to the direct current that
passes through it.
Burner.
e burner is made up from 11 horizontal Venturi pipes (5)
into which the gas is injected by just as many nozzles (6)
mounted on the relevant collector (7), whose diameter varies
according to the type of gas used (see technical data).
Ignition takes place thanks to an integrated P.C.B. that controls
the ignition and detection electrode (4).
Ignition and detection electrode (4).
In the ignition mode, it is controlled by the integrated P.C.B.
that causes an electric spark between its ends and the surface of
the burner on the contact of which the air-gas mix ignites.
Once the burner is on, it detects ame presence on the burner
allowing the integrated P.C.B. to conclude the ignition cycle
and to vary the gas pressure as required.
It is positioned on the front of the burner in correspondence
with the central ramp.
COIL POWER SUPPLY RESISTANCE
EV1 230 V AC 6,25 kΩ
EV2 230 V AC 860 Ω
Modulation coil 250mA DC (G20)
320mA DC (L.P.G.) 22 Ω
Reference values with boiler at maximum power
Note: for correct ignition and detection of the boiler always
respect the quotes stated in the gure below.
7
4
5
6

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Gas adjustments.
e minimum and maximum pressure adjustments are perfor-
med by acting on the gas valve and must be carried out respec-
ting the values stated in the tables relative to each generator for
the corresponding type of gas (see technical data).
e features of this appliance allow to dierentiate the mini-
mum pressure adjustments during functioning in the CH
and DHW functioning modes.
e minimum pressure adjustment made on the gas valve, in
fact corresponds to the minimum pressure in the DHW
mode (7.0 kW = 6,020 kcal/h) while, for that which con-
cerns central heating, the minimum pressure (9.5 kW =
8,170 kcal/h) can be adjusted by means of the "Minimum
heating output" parameter. is can be programmed on the
integrated P.C.B. (see integrated P.C.B. programming).
e measurements are taken using a dierential manometer,
whose pressure point is connected to the vas valve outlet (4)
(see gure).
Honeywell VK 4105 gas valve.
Maximum pressure adjustment.
Withdraw DHW after having adjusted (using the keys on the
control panel) the temperature at maximum.
Act in a clockwise direction on the brass nut (3) to increase
the pressure to the burner and in a clockwise direction to
decrease it.
Minimum pressure adjustment
(to be carried out after the maximum pressure adjustment).
After having removed the electric power supply to the modu-
lating coil, act in a clockwise direction on the brass nut (2) to
increase pressure to the boiler and in an anti-clockwise manner
to decrease it, making sure the brass nut is blocked (3).
Key:
1 - Coil
2 - Minimum power adjustment nut
3 - Maximum power adjustment nut
4 - Gas valve outlet pressure point
5 - Gas valve inlet pressure point
6 - Protection hood
Valvola VK 4105

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Key:
1 - Coil
2 - Minimum power adjustment screws
3 - Maximum power adjustment nut
4 - Gas valve outlet pressure point
5 - Gas valve inlet pressure point
6 - Protection hood
SIT 845 valve
SIT 845 gas valve.
Maximum pressure adjustment.
Withdraw DHW after having adjusted (using the keys on the
control panel) the temperature at maximum.
Act in a clockwise direction on the brass nut (3) to increase
the pressure to the burner and in a clockwise direction to
decrease it.
Minimum pressure adjustment
(to be carried out after the maximum pressure adjustment).
After having removed the electric power supply from the mo-
dulation coil, act in an anti-clockwise direction on the screw (2)
to increase the pressure to the burner and in an anti-clockwise
direction to decrease it.
Gas transformation.
e adaptation to the type of gas dierent to that for which
the boilers are prepared as per standard is performed using the
relevant kit (methane or LPG).
e transformation consists in the replacement of the bur-
ner nozzles and the modication of the parameter "P1",
programmable on the integrated P.C.B. (see integrated P.C.B.
programming).
e maximum and minimum DHW pressures are adjusted
on the gas valve in the above-described way.
e adjustments of the minimum and maximum outputs in
CH mode can be set using parameters (see integrated P.C.B.
functioning).
e burner ignition pressure is not adjusted as the particu-
lar functioning of the P.C.B. does not require this type of
calibration (see integrated P.C.B. functioning).

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Disassembly of bithermal heat exchanger and ue hood.
Before disassembling the components, make sure that the
gas cock is closed and empty the CH system and the DHW
circuit.
Flue hood disassembly (1).
Loosen the two screw fasteners (9) of the cross-member (8),
then loosen the two screws (2) that x the ue hood (1) to the
combustion chamber support.
Disassembly of the bithermal heat exchanger (3).
Loosen the four screw fasteners (10) of the combustion cham-
ber face (7) and the anti-reection sheet steel (11), then loosen
the two screws (2) that x the ue hood (1) to the combustion
chamber support.
Extract the locking clips (6) in a way to free the heat exchanger
(3) ow and return pipes (system side), the safety clips (4) and
successively the other locking clips (5) in a way to free the heat
exchanger (3) inlet and outlet pipes (DHW side).
At this point it is possible to lift the heat exchanger in a way
to free it from the coupling with the relative pipes.
N.B.: when restoring the connection between bithermal heat
exchanger and pipes, pay particular attention to the correct
positioning of the O-ring and make sure the pipe locking clips
are tted correctly, in a way to prevent their undermining.
6
54
11
10
10
9
8
7
1
10
3
2

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e electric circuit of the NIKE Star 24 3 E is completely
interlocked to a P.C.B. with integrated microprocessor, which
controls the functions of the generator.
e control and safety devices partly operate at network voltage
(230 V AC) and partly at low voltage.
Electric circuit.
230 V AC circuit.
Safety devices and controls.
ey cut o the power supply to the circuit when the current
absorbed exceeds 3.15A.
ey are mounted on the integrated P.C.B.
Phase fuse (F1)
Neutral (F2)
Fuse
3.15 AF 250 V
Key:
B1 - Flow probe
B2 - Domestic hot water probe
CRD - Digital Remote Control (optional)
DS1 - Display
E3 - Ignition and detection electrode
E4 - Safety thermostat
E6 - Flue safety thermostat
F1 - Phase fuse
F2 - Neutral fuse
M1 - Boiler pump
S2 - Selector switch functioning
S3 - Reset block key
S4 - Domestic hot water ow switch
S5 - System pressure switch
S20 - Room thermostat (optional)
S21 - Domestic hot water temperature
increase key
S22 - Domestic hot water temperature
decrease key
S23 - Heating temperature increase key
S24 - Heating temperature decrease key
T1 - Ignition transformer
T2 - Boiler card transformer
U1 - Rectier inside the gas valve connec-
tor (Only available on Honeywell gas
valves)
X40 - Room thermostat jumper
Y1 - Gas valve
Y2 - Gas valve modulator
It detects burner ignition from where the ame is hit.
It is connected to the integrated P.C.B.
e electrode also acts as an ignition electrode.
Detection electrode
(E3)
Power supply
230 VAC 50
Hz.
Blue
Brown
Yellow/Green
Blue
Brown
Blue
Brown
Black
Black
Grey Grey
White
White
White White Black
Black
Red
Red
Grey
Grey
THE X6 CONNECTOR IS
USED FOR AUTOMATIC
TEST
USER INTERFACE
N.B.: THE USER
INTERFACE IS FOUND
ON THE WELDING SIDE
OF THE BOILER
ELECTRONIC BOARD

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Low voltage circuit.
Safety devices and controls.
Allows to unblock the boiler after ignition block safety intervention
or over-heating, it allows to activate the chimney sweep function.
If pressed together with the functioning mode selector switch (S2),
it allows to set boiler parameters.
Reset Button
(S3) Button
Loads.
e board is always powered independently from the functioning selector switch position
(S2) (see integrated P.C.B. functioning).
Integrated P.C.B.
It is powered by the integrated P.C.B. when there is a CH or anti-freeze request.
Allows circulation in the primary circuit.
Boiler pump
(M1)
It is controlled by the integrated P.C.B. that causes an electric spark between its ends and
the surface of the burner on the contact of which the air-gas mix ignites.
e electrode also acts as a detection electrode.
Ignition electrode
(E3)
Allows long distance control of the generator (SUM/WIN mode
selection, temperature adjustment and indication, alarms display, reset,
etc.) and acts as weekly timer thermostat.
If the CRD is installed, the pre-existing X40 jumper must be
eliminated.
Digital Remote Control
(CRD)
(optional)
See Digital
Remote Control
functioning
(CRD)
Following withdrawal of DHW it acts on the integrated P.C.B.
causing functioning in DHW mode.
In stand-by it enables functioning in CH mode.
Domestic hot water ow
switch (S4)
Contact in
cut-o
When the pressure of the boiler circuit is below 0.3 bar it determines
burner switch-o.
System pressure switch
(S5)
Contact in
cut-o
It is powered by the integrated P.C.B. when burner ignition is necessary.
For the SIT 845 gas valve it is powered by the mains voltage.
For gas valve VK 4105 it is powered at network voltage rectied by means of a diodes
jumper (U1) contained inside the gas valve connector.
Allows the passage of gas to the burner.
Gas valve (Y1)
(main coils)

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When the safety thermostat is exceeded (100 °C) the burner is
switched o.
It is positioned at the exit of the main heat exchanger.
Safety thermostat
(E4)
Klixon thermostat
with normally
closed contact
It is powered by the integrated P.C.B. with variable direct current.
It allows to vary the gas pressure at the burner.
Gas valve modulator
(Y2)
Loads.
If there is only little ue draught, act on the integrated P.C.B.
blocking boiler functioning for 30 minutes.
It is positioned on the right side of the ue hood.
Flue safety thermostat
(E6)
Klixon thermostat
with normally
closed contact
e possible functioning mode selections are:
= Circuit powered, the anti-freeze and anti-block fun-
ctions remain active, the post-circulation function is terminated.
( ) = Boiler functioning in SUMMER mode.
( ) = Boiler functioning in WINTER mode.
Functioning mode selector
switch
(S2)
Button
Enables functioning in CH mode when the room temperature is
below that requested.
If the room thermostat is installed the pre-existing X40 jumper
must be eliminated.
Room thermostat (S20)
(external optional)
Contact in
cut-o
Allows the integrated P.C.B. to detect the temperature of the pri-
mary circuit ow water.
Its breakage blocks burner functioning both in central heating and
domestic hot water modes.
It is positioned on the bithermal heat exchanger ow pipe.
Flow probe
(B1)
NTC probe
10 kΩ 25 °C
It allows the integrated P.C.B. to detect the temperature of the
exiting domestic hot water.
Its breakage blocks functioning in DHW mode but functioning is
allowed in DHW phase.
It is inserted onto the DHW outlet pipe connected to the bithermal
heat exchanger.
Domestic hot water probe
(B2)
NTC probe
10 kΩ 25 °C

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Electric circuit.
CH mode.
Operating with room thermostat.
By using the button (S2) to select (Winter) functioning,
boiler functioning in the CH mode is enabled.
On closure of the room thermostat (S20), if the contact of the
system pressure switch (S5) is closed (pressure detected in the
primary circuit exceeding the minimum value) the integrated
P.C.B. powers the boiler pump (M1) by means of relay K3.
With the consent of the safety thermostat (E4), the ue safety
thermostat (E6) and if the temperature detected by the NTC
ow probe (B1) is lower than the setting made on the boiler
control panel, the integrated P.C.B. excites the requested relay
K2. is causes the closure of the two contacts, allowing to
start the ignition cycle, rst controlling the ignition/detection
electrode (E3) and simultaneously, both the coils of the gas
valve (Y1).
e ignition of the burner is detected by the integrated P.C.B.
by means of the ionisation electrode (E3).
Operation with Digital Remote Control (Op-
tional).
By selecting the functioning in Winter mode on the Digital
Remote Control on the panel (CRD), boiler functioning in
CH mode is enabled.
If the conditions detected CRD require ignition in CH mode,
the integrated P.C.B. powers the boiler pump (M1) through
relay K3 and burner ignition takes place as described above.
N.B.: every time switch o occurs when temperature is reached,
the integrated P.C.B. blocks burner functioning in CH mode
for a period of time equal to that set with board parameters
(see integrated P.C.B. functioning).
HIGH
VOLTAGE
LOW
VOLTAGE
CONTROL LOGIC MICROPROCESSOR
USER INTERFACE

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Electric circuit.
DHW mode.
Operation.
By using the button (S2) to select (Summer) (Estate) or
(Winter) functioning, boiler functioning in the CH mode
is enabled.
A withdrawal of DHW causes the closure of the DHW
ow switch contact (S4) and enables functioning in DHW
mode.
e board checks closure of the system pressure switch contact
(S5) (pressure detected in the primary circuit exceeding minimum
value).
e boiler pump (M1) is not made to function in DHW
or is switched o when there is a CH request in progress
following the opening of relay K3.
If the temperature detected by the DHW NTC probe (B2) is
below the setting on the boiler control panel (or on the CRD
if mounted) boiler ignition is requested.
With the consent of the safety thermostat (E4) and the con-
sent of the ue safety thermostat (E6), the board closes the
contact of relay K4 and requested relay K2. is causes the
closure of the 2 contacts, allowing to start the ignition cycle,
rst controlling the ignition electrode (E3) and successively,
both coils of the gas valve (Y1).
e ignition of the burner is detected by the integrated P.C.B.
by means of the ionisation electrode (E3).
HIGH
VOLTAGE
LOW
VOLTAGE
CONTROL LOGIC MICROPROCESSOR
USER INTERFACE

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STNS3E ed 09/08 NIKE Star 24 3 E
Technical documentationTechnical documentation
Integrated P.C.B. (Printed Circuit Board).
Inside the control panel the boiler is equipped with a P.C.B.
with microprocessor for control of the appliance's electric devi-
ces, which takes care of linear modulation of burner power.
A display shows the functioning status of the appliance, in-
dicating any intervention of the safety devices, with which it
is supplied.
e board that equips all models, whether conventional
ue or sealed chamber (NIKE/EOLO Star 24 3 E) is the
same. Recognition of the dierent types of boiler functioning
takes place automatically by means of the electric wiring of
the appliance.
e integrated P.C.B. is always powered independently from
the functioning position determined by the functioning mode
selector switch (S2).
e board carries out a periodical self-check to control its
correct functioning. During functioning in CH mode or with
boiler in stand-by, the function activates every 18 hours from
the last check/powering of the boiler. If functioning in DHW
mode, the self-check starts within 10 minutes after the end f the
withdrawal in progress for the duration of about 10 seconds.
N.B.: during self-check the boiler remains o, including
signalling.
Operation.
Central heating request.
By using the button (S2) to select (Winter) functioning,
boiler functioning in the CH mode is enabled.
On closure of the room thermostat (S20), if the contact of the
system pressure switch (S5) is closed (pressure detected in the
primary circuit exceeding the minimum value) the integrated
P.C.B. powers the boiler pump (M1) by means of relay K3.
With the consent of the safety thermostat (E4), the ue safety
thermostat (E6) and if the temperature detected by the NTC
ow probe (B1) is lower than the setting made on the boiler
control panel, the integrated P.C.B. excites the requested relay
K2. is causes the closure of the two contacts, allowing to
start the ignition cycle.
In the rst seconds after the gas valve has been powered (Y1),
the current to the modulation coil (Y2) is limited to the pre-set
soft ignition current.
Successively, the burner goes to the minimum value set by
setting the "Central heating minimum output*" parameter,
to then reach the maximum value set (if requested) by setting
the "Central heating maximum output*" parameter, in a
time determined by the setting of the " Central heating ramp
timing*" parameter.
Successively, ame modulation takes place with reference to the
dierence between the temperature set on the boiler control
panel and that detected by the DHW probe (B1).
On exceeding (+5°C) the temperature set, the contact of relay
K2 is opened with consequent burner switch o, whose switch/
on time depends on the setting of the "Central heating ignition
timer*" parameter.
Every time the burner switches o the pump functions for
another 30 seconds.
* see integrated P.C.B. programming.
X1 X10 X7 X4 X2
40
(+)
41
(-)
CRD / TA
X6
FUSES
Transformer

19
STNS3E ed 09/08 NIKE Star 24 3 E
Technical documentation Technical documentation
DHW request.
A withdrawal of DHW causes the closure of the DHW
ow switch contact (S4) and enables functioning in DHW
mode.
When the boiler functions in DHW mode, the boiler pump
(M1) is not made to function or is switched o when there
is a CH request in progress following the opening of relay
K3.
Successively, burner ignition takes place in the same way as
the CH mode.
In the rst seconds after the gas valve has been powered (Y1),
the current to the modulation coil (Y2) is limited to the pre-set
soft ignition current.
When the ame has been detected, the modulation coil signal
is increased in a way to immediately reach (if requested) the
maximum output adjusted on the gas valve.
Successively, ame modulation takes place with reference to the
dierence between the temperature set on the boiler control
panel and that detected by the DHW probe (B2).
Relay K2 contact is opened when the value of 65 °C is exce-
eded. is is closed again as soon as the temperature drops
back below 64 °C.
An increase of the ow temperature beyond the limitation
intervention point (80 °C) causes a reduction of the modula-
tion current in a proportional manner, in a way to limit this
temperature.
Central heating anti-freeze request.
When the temperature detected by the CH ow probe (B1)
falls below 4 °C, the board gives consent for ignition and keeps
the generator working with the burner at minimum output
until a boiler temperature equal to 42 °C is reached (radiators
anti-freeze).
e function is always active independently from the selection
made on the functioning mode selector switch.
DHW anti-freeze request.
If the temperature detected by the DHW probe (B2) falls below
4 °C, the board gives consent for boiler ignition and keeps the
generator working with the burner at minimum output until
a temperature of 8 °C is detected by the DHW probe. Post-
circulation is then activated in the central heating mode with
duration of 30 seconds.
During functioning, the water in the primary circuit remains
below 42 °C as on reaching this temperature the board switches
the burner o.
e function is always active independently from the selection
made on the functioning mode selector switch.
"Chimney sweep" request.
Press the "Reset" button (S3) for at least 10 seconds. On its
release the board gives consent for ignition of the generator
and keeps it functioning at maximum heating output set for
15 minutes.
During this period only the limit thermostat function is
respected (90 °C), which is performed by the central heating
ow probe (B1).
e function is signalled on the boiler display by the ashing
symbols ( and ). It cannot be inserted if a DHW request
is in progress.
It can be cut-o by removing the power supply to the circuit,
taking the boiler to the (Stand-by), position, making a
DHW request or after 15 minutes.