Immergas NIKE Star 23 kW User manual

NIKE Star 23 kW
Instantaneous wall-hung
with open chamber boilers
NIKE Star 23 kW

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NIKE Star 23 kW
Compact instantaneous wall-hung
conventional flue boiler.
NIKE Star 23 kW
NIKE Star 23 kW is a wall-hung conventional flue boiler for
heating and production domestic hot water.
It is distinguished by its compact size (H=780 mm, W=450
mm, D=250 mm), has an heat output of 23.3 kW (20,000
kcal/h).
A microprocessor controlled electronic board adjusts and
controls the appliance (burner ignition, temperature adjustment,
flame modulation and diagnostics) and the operating parameters
can be displayed and set by means of a digital interface with
display and push buttons.
General features.
e hydraulic circuit is equipped with a copper bithermal type
water-gas exchanger for the production of hot water for central
heating and domestic use, an automatic by-pass on the system
and a flow switch for tapping the domestic hot water.
Legend:
G - Gas supply
AC - Hot water outlet
AF - Cold water inlet
R - System return
M - System delivery
V - Electrical supply
Main dimensions and main connections.
Height (mm) Width (mm) Depth (mm)
780 450 250
Connections
GAS DOMESTIC
WATER SYSTEM
G AC AF R M
3/4” 1/2” 1/2” 3/4” 3/4”

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Legend:
1 - Filling valve
2 - Boiler pressure gauge
3 - D.h.w. probe
4 - Gas valve
5 - D.h.w. flow switch
6 - Combustion chamber
7 - Draught diverter
8 - Flue safety thermostat
9 - Delivery probe
10 - Safety thermostat
Main components.
11 - System expansion vessel
12 - Automatic air vent
13 - Boiler circulator
14 - System pressure switch
15 - Manifold
16 - 3-bar safety valve
17 - Draining cock
18 - Rapid heat exchanger
19 - Ignition and detection electrodes
20 - Burner

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Legend:
1 - Reset Push Button
2 - Stand-by / Summer / Winter Push Button
3 - Push button (+) to increase d.h.w. temperature
4 - Push button (-) to reduce d.h.w. temperature
5 - Push button (+) to increase system water temperature
6 - Push button (-) to reduce system water temperature
7 - Boiler pressure gauge
8 - D.h.w. functioning mode
Control panel.
9 - Displays temperatures and error codes
10 - Unit of measure
11 - Central heating functioning mode
12 - Winter
13 - Summer
14 - Power supplied
15 - Burner operating

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e central heating circuit, with relevant control and safety
devices, is operated every time a central heating request is
made.
Operation.
e heat contained in the fumes produced by combustion
is absorbed by the copper blades of the water-gas exchanger
(7) which, in turn, transfers it to the water circulating inside
thanks to the boiler circulator (14).
e hot water is then transferred directly into the central heat-
ing system through the delivery (M) and return (R) pipes.
Legend:
1 - D.h.w. probe
2 - D.h.w. flow switch
3 - Gas valve
4 - Flow limiter
5 - Draining cock
6 - Burner
7 - Rapid heat exchanger
8 - Draught diverter
9 - Flue safety thermostat
10 - System expansion vessel
11 - Delivery probe
12 - Safety thermostat
13 - Automatic air vent
14 - Boiler circulator
15 - System pressure switch
16 - Automatic by-pass
17 - 3-bar safety valve
18 - Filling valve
G - Gas supply
AC - D.h.w. outlet
AF - Cold water inlet
R - System return
M - System delivery
Hydraulic circuit.
Primary circuit (Boiler Circuit).
Hot water for central heating and domestic use is produced
by two separate circuits that work as required.

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Boiler circulator (1).
e pump works on the primary circuit return and is located
on the brass manifold assembly.
It is connected to the enbloc and primary exchanger by means
of threaded fittings.
e automatic valve vent is housed on the body (2).
Primary exchanger.
is is a water-gas bithermal type blade exchanger with pipes
and fins in copper for the production of hot water for central
heating and domestic use.
It therefore works directly on both circuits to which it is con-
nected by pipes with threaded fittings (3) with a flat gasket
seal (4).
e 6 oval pipes it consists of, inside which flows the water of
the central heating circuit, contain an equal number of “cross-
shaped” pipes for the direct transit of domestic hot water (see
illustration below).
ese pipes are plumbed in parallel in groups of three on the
central heating circuit and in series on the d.h.w. circuit.
e overheating safety thermostat (2) is fixed on the side of
the exchanger exit with a fork (1).
e relevant NTC delivery probe is screwed into place on the
central heating delivery pipe (5).
Head flow rate graph.
e available head the appliance is able to guarantee to the
system in the central heating mode depends on the flow rate
which is shown in the following graph where we can see the
characteristic curve with the pump working at second and
top speed.
Head (m H2O)
A = Head available to the system at third speed
B = Head available to the system at second speed
Head (kPa)
A
2
1
Domestic
cold
water
inlet Domestic
hot
water
outlet
Domestic
hot
water
outlet System
delivery
System
return
Exchanger pipe section
System
central
heating circuit
D.h.w.
circuit
B
Flow rate (l/h)

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Safety devices and controls.
Automatic system by-pass (4).
is device ensures circulation in the central heating circuit
even when this is prevented by the system’s high resistance.
It works between the delivery and return of the central heating
circuit and is accessible after having unscrewed the cap (5) on
the brass manifold’s hook (1).
System water pressure switch (7).
is is an absolute pressure switch that reads the pressure inside
the central heating circuit.
It is housed in the manifold (1) and coupled to a microswitch
that prevents the boiler working when the pressure measured
is below 0.3 bar.
is prevents the bithermal exchanger from overheating.
Filling valve (3).
is valve is between the boiler circuit and the domestic cold
water inlet and permits pressurisation of the central heating
system.
It is located underneath the brass manifold (1) to which it is
screwed.
3-bar safety valve (2).
is valve prevents the safety pressure being exceeded in the
circuit (3 bar).
It is on the front of the manifold (1), secured to it on the side
with an Allen screw.
When this valve triggers, water exits from the boiler return
pipe.
Automatic air vent (8).
It automatically expels any gaseous substances from the cir-
cuit.
It is mounted on the pump’s delivery side.
Expansion vessel (9).
It compensates for variations in volume as a result of heating
the water which also limits pressure variations.
It has a 6-litre capacity (4.0 useful litres) and a pre-load pres-
sure of 1.0 bar.
It is located on the right of the boiler alongside the sealed
chamber and is connected to the return manifold (1) by a
copper pipe (6) with threaded fittings.
8
9
6
7
4
5
1
2
3
6
Central
heating
exchanger
delivery
Pump
return
System
delivery
System
return

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Secondary circuit (D.h.w. circuit).
Operation.
When domestic hot water is drawn, cold water flows inside
the flow switch (4) which closes the electrical contact coupled
to it (see the electrical circuit).
As a result, the adjustment circuit starts the d.h.w. priority
phase that ignites the burner (3) and, if there is an ongoing
central heating request, switches the boiler circulator off.
In this way, the heat in the fumes produced by combustion is
absorbed by the copper blades of the bithermal exchanger (2)
and transferred to the heating circuit water which, in turn,
transfers it to the domestic water circuit flowing through the
“cross-shaped” hot water circuit pipes (1).
D.h.w. flow switch.
Whenever hot water is drawn at a rate of at least 2.5 l/min and
with a dynamic pressure of 0.3 bar, the flow switch (2) enables
the boiler to operate in the d.h.w. mode.
is is done by means of a magnet that, by lifting when hit by
the flow of cold water, moves near to an electrical contact (reed
relay) causing it to move thanks to the effect of the magnet.
When the contact closes, which is located outside the pipe
through which the water flows, it enables the modulation board
to start the domestic hot water priority operating mode.
It consists of two blocks (one in brass and one in plastic) that
are coupled together and locked with a pin (3).
An 8.0 l/min (2 bar) flow limiter (1) is installed at the flow
switch exit.
Bithermal exchanger
(see the central heating circuit).
Note: to ensure long life and have an exchanger that is always
efficient, we recommend installing the “polyphosphates dispenser
kit” if the water is likely to lead to scale forming. For example,
this kit is recommended when the hardness of the water exceeds
25 French degrees.
1
2
3
Cold domestic
water inlet

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e circuit consists of an atmospheric burner and a modu-
lating gas valve for gas combustion and flow adjustment
respectively.
Operation.
When the main coils are energised (3) both the inner valve
shutters open allowing gas to flow towards the burner.
e flow rate/outlet pressure is set by means of the gas valve
stabiliser and the modulation coil (1).
By mean of the burner nozzles (7) fuel is injected into the Ven-
turi tubes (ramps) inside which the air-gas mixture is obtained
that is ignited by the spark from the ignition electrode (5).
Modulating gas valve.
e gas valve (SIT 845) features two main coils (3) and a
modulation coil (1) controlled by the integrated board.
e maximum and minimum outlet pressure can be set with
this valve (see gas settings).
Main electric coils (3).
ey are two ON-OFF type coils supplied (230 Vac) by the
integrated board when the burner has to be ignited.
ey are electrically connected in parallel and supplied by
mains power through a special connector (2).
Modulation coil (1).
is is a low voltage coil controlled by the integrated board.
It controls the gas valve stabiliser and permits changing of
the outlet pressure in a way proportionate to the DC running
through it.
Gas circuit.
Burner.
e burner consists of 12 horizontal Venturi tubes (6) inside
which the gas is injected by an equal number of nozzles (7)
mounted on the specific manifold (8) and whose diameter
varies according to the type of gas used (see technical data).
Ignition occurs by means of an integrated p.c.b. that controls
the ignition (5) and detection (4) electrodes.
Ignition electrode (5).
is is controlled by the integrated board that produces an
electrical charge between its end and the burner surface which
is responsible for igniting the air-gas mix.
is electrode is at the front of the burner in line with the
centre ramp.
Detection electrode (4).
is is controlled by the integrated board and detects burner
ignition.
It is positioned at the front of the burner on the same ramp
as the ignition electrode.
1
3
2