Immergas NIKE Mini 24 Export User manual

NIKE Mini
24-28 Export
Compact instantaneous
wall-hung conventional
flue boilers
NIKE Mini 24-28 Export
NIKE Mini 24 S Export
NIKE Mini
24 S Export
Compact wall-hung
conventional flue boilers
for central heating only

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NIKE MINI 24-28 Export
Compact instantaneous wall-hung conventional
flue boiler (type B).
NIKE Mini 24
NIKE Mini 28
NIKE Mini is a wall-hung conventional flue boiler for heating
and producing domestic hot water and is distinguished by its
compact size.
It is available with an output power of 24 kW (20,640 kcal/h)
and 28 kW (24,080 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 panel and push buttons.
With the new electronics the boiler can be connected to the
Remote Digital Control for controlling the boiler remotely
with the utmost ease and also integrates the timer/room
thermostat, boiler diagnostics and delivery temperature ther-
moregulation functions.
e boiler is fitted with a safety antifreeze system as a
standard feature that protects it against temperatures as low
as -5 °C.
e hydraulic circuit is equipped with a copper water-gas
exchanger, a pump unit in a composite material and a new
electric 3-way valve unit that, according to requirements, allows
the boiler water to circulate in the central heating system or
in a stainless steel plate exchanger for the instant production
of domestic hot water; the primary circuit also features an
automatic by-pass and a 3-bar safety valve.
General features.

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NIKE Mini 24 S Export
Compact, wall-hung conventional flue boiler for
central heating only (type B).
NIKE Mini 24 S
NIKE Mini S is a wall-hung conventional flue boiler for central
heating only with an output power of 23.6 kW (20,296 kcal/h)
which, using an optional kit comprising a 3-way electric valve
and a domestic hot water probe together with the necessary
wiring (that can be connected directly to the integrated board),
can be combined with a separate storage tank to produce
domestic hot water.
A microprocessor controlled electronic boards sees to adjust-
ing and controlling the appliance (burner ignition, temperature
setting, flame modulation and diagnostics) which, by means of a
digital interface complete with display and push buttons, lets
you see and adjust the operating parameters.
With the new electronics the appliance can be connected
to the Remote Digital Control for controlling the boiler
remotely with the utmost ease and also integrates the timer/
room thermostat, boiler diagnostics and delivery temperature
thermoregulation functions.
e boiler is fitted with a safety antifreeze system as a
standard feature that protects it against temperatures as low
as -5 °C.
e hydraulic circuit is equipped with a copper water-gas
exchanger, a pump unit in a composite material and a delivery
manifold on which an automatic by-pass and safety valve,
calibrated at 3 bar, are housed.
General features.

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Legend:
G - Gas supply
AC - Domestic hot water outlet
AF - Cold water inlet
R - System return
M - System delivery
V - Electrical connection
NIKE Mini 24 main dimensions and connections.
Legend:
G - Gas supply
AC - Domestic hot water outlet
AF - Cold water inlet
R - System return
M - System delivery
V - Electrical connection
NIKE Mini 28 main dimensions and connections.
Height (mm) Width (mm) Depth (mm)
740 450 310
Connections
GAS DOMESTIC
WATER SYSTEM
G AC AF R M
3/4” 1/2” 1/2” 3/4” 3/4”
Height (mm) Width (mm) Depth (mm)
745 450 250
Connections
GAS DOMESTIC
WATER SYSTEM
G AC AF R M
3/4” 1/2” 1/2” 3/4” 3/4”

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NIKE Mini 24 S main dimensions and connections.
Legend:
G - Gas supply
RR - System filling
R - System return
M - System delivery
V - Electrical connection
Height (mm) Width (mm) Depth (mm)
745 450 250
Connections
GAS WATER SYSTEM
G RR R M
3/4” 1/2” 3/4” 3/4”

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Legend:
1 - Burner
2 - D.h.w. flow switch
3 - Gas valve
4 - Filling valve
5 - Boiler pressure gauge
6 - Flue safety thermostat
7 - Draught diverter
8 - Delivery probe
9 - Overheating safety thermostat
10 - System expansion vessel
11 - Combustion chamber
12 - Circulator boiler
13 - 3-bar safety valve
NIKE Mini 24 main components.
14 - Automatic by-pass
15 - Motorised 3-way valve
16 - Draining valve
17 - Primary exchanger
18 - Ignition and detection electrodes
19 - Automatic air vent
20 - D.h.w. exchanger

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Legend:
1 - Burner
2 - D.h.w. flow switch
3 - Gas valve
4 - Filling valve
5 - Boiler pressure gauge
6 - Flue safety thermostat
7 - Draught diverter
8 - Delivery probe
9 - Overheating safety thermostat
10 - System expansion vessel
11 - Combustion chamber
12 - Circulator boiler
13 - 3-bar safety valve
NIKE Mini 28 main components.
14 - Automatic by-pass
15 - Motorised 3-way valve
16 - Draining valve
17 - Primary exchanger
18 - Ignition and detection electrodes
19 - Automatic air vent
20 - D.h.w. exchanger

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Legend:
1 - Burner
3 - Gas valve
4 - Filling valve
5 - Boiler pressure gauge
6 - Flue safety thermostat
7 - Draught diverter
8 - Delivery probe
9 - Overheating safety thermostat
10 - System expansion vessel
11 - Combustion chamber
12 - Circulator boiler
NIKE Mini 24 S main components.
13 - 3-bar safety valve
14 - Automatic by-pass
16 - Draining valve
17 - Primary exchanger
18 - Ignition and detection electrodes
19 - Automatic air vent

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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 - Visual display of temperatures and error codes
10 - Unit of measure
11 - Central heating functioning mode
12 - Winter
13 - Summer
14 - Power supplied
15 - Flame presence
Note for the NIKE Mini 24 S version:
Although push buttons (3) and (4), for setting the domestic
hot water temperature, and push button (2), (“summer” mode,
symbol “13), are present and can be selected, they are not
enabled to work.

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Legend:
1 - 3-bar safety valve
2 - Filling valve
3 - Gas valve
4 - Burner
5 - Primary exchanger
6 - Draught diverter
7 - Flue safety thermostat
8 - Delivery probe
9 - Overheating safety thermostat
10 - System expansion vessel
11 - Automatic air vent
12 - Circulator boiler
13 - Automatic by-pass
14 - Delivery manifold
15 - Draining valve
G - Gas supply
RR - System filling
R - System return
M - System delivery
NIKE Mini 24 S hydraulic circuit (central heating only).
e primary circuit with relevant control and safety devices
is triggered each time there is a request for central heating or
antifreeze.

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e primary circuit, with relevant control and safety devices,
is operated each time either a central heating or d.h.w.
request is made.
Operation (see NIKE Mini).
e heat contained in the fumes produced by combustion is
absorbed by the copper blades of the water-gas primary ex-
changer (6) which, in turn, transfers it to the water circulating
inside thanks to the boiler circulator (13).
e water is transferred directly into the system or can be devi-
ated to the instant stainless steel plate exchanger (14).
is depends on the position of the motorised 3-way valve
(15) which, when idle allows the water to flow to the d.h.w.
exchanger (14) while if a central heating request is made it
deviates the flow to the system’s delivery (M) and return (R)
pipes.
Legend:
1 - D.h.w. flow switch
2 - Flow limiter
3 - Filling valve
4 - Gas valve
5 - Burner
6 - Primary exchanger
7 - Draught diverter
8 - Flue safety thermostat
9 - Delivery probe
10 - Overheating safety thermostat
11 - System expansion vessel
12 - Automatic air vent
13 - Circulator boiler
14 - D.h.w. exchanger
15 - 3-way valve (motorised)
16 - Automatic by-pass
17 - Draining valve
18 - 3-bar safety valve
G - Gas supply
AC - Domestic hot water outlet
AF - Cold water inlet
R - System return
M - System delivery
NIKE Mini Hydraulic circuit.
Primary circuit (Boiler Circuit).
e hot water for central heating and domestic use is produced
by a primary and a secondary (d.h.w.) circuits that work as
required.

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Head flow rate graph.
e course of the curve that represents the flow rate/head ratio
available for the system depends on how fast the circulator is
working which, depending on the position, gives the system
a bigger or smaller head. e characteristic curves are shown
in the following graphs.
A = Head available to the system at third speed (with automatic by-pass)
B = Head available to the system at second speed (with automatic by-pass)
NIKE Mini 28
NIKE Mini 24 - 24 S
Head (m H2O)
Flow rate (l/h)
Head (kPa)
A
B
A
B
Head (m H2O)
Flow rate (l/h)
Head (kPa)

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Boiler circulator (1).
e pump works on the primary circuit return; it is part of the
pump body unit made in a composite material.
e automatic air vent (2) is housed directly on the body.
1
2
Primary exchanger (1).
It is a lamellar water-gas exchanger with copper tubes and
fins and at whose outlet (delivery) the central heating NTC
delivery probe (6) and the overheating safety thermostat (2)
are located.
e four pipes it is made of are connected in series (1).
It is connected to the circulator delivery and to the primary
circuit delivery by means of push-fitted pipes (3) and O rings
(5) and locked with forks (4).
e exchangers of the 24 and 28 versions differ in the number
of fins (80 in the 24 - 24 S version and 98 in the 28 version)
and in the different layout of the delivery and return pipes
(see drawing).
1
34
5
2
6
Delivery
Return
1
34
5
2
6
NIKE Mini 24
Delivery
Return
NIKE Mini 28

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Exchanger
delivery
D.H.W.
EXCHANGER
DELIVERY
Motorised 3-way diverter valve for combi mod-
els.
It is an electric motor (1) connected to the 3-way unit (2) and
locked by a fork that allows, according to the request made
(d.h.w. or central heating), boiler water to flow into the central
heating system or in the d.h.w. plate exchanger.
is depends on the position of the shutter (4) which closes
passage to the system while simultaneously opening it to the
d.h.w. exchanger (d.h.w. position) or vice versa (central heating
position).
e motor (1) is made to work by the electronic board and,
with each 180° rotation, the shutter (4) moves into both
positions.
e hydraulic part consists of a brass unit (2).
Operation in the central heating mode.
e shutter’s (4) counteracting spring (3) is not compressed
(central heating position), keeping passage to the d.h.w. plate
exchanger closed and passage to the system delivery open.
Both the spring (3) and shutter (4) are located inside the 3-
way brass body (2).
Operation in the d.h.w. mode.
e standard position of the hydraulic unit is always in the
d.h.w. mode.
e electric motor (1) pushes the rod (5) to which the shutter
(4) is connected which closes passage to the system, simultane-
ously opening it to the d.h.w. plate exchanger, the shutter’s (4)
contrasting spring (3) is compressed (d.h.w. position).
Both the spring (3) and shutter (4) are located inside the 3-way
valve brass body (2).
EXCHANGER
DELIVERY
SYSTEM
DELIVERY
1
2
3
4
5
Exchanger
return
System
delivery
D.h.w.
exchanger
delivery

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Safety devices and checks for combi models.
Automatic system by-pass (3).
is device guarantees the circulation of water in the central
heating circuit even when it would be prevented by the high
resistance of the system.
It works between the central heating delivery and return,
inserted inside the by-pass fitting (4) that connects the pump
unit (2) to the 3-way unit.
System filling unit (7).
is is a valve positioned between the boiler circuit and the
domestic cold water inlet and makes it possible to pressurise
the heating system.
is unit is connected to the d.h.w. flow switch (6) by means
of a threaded fitting and to the pump unit (2) by means of
an O ring.
Automatic air vent (1).
It automatically expels gaseous substances from the boiler
circuit.
It is mounted on the circulator delivery, directly on the pump
unit (2).
3-bar safety valve (5).
is valve prevents the safety pressure being exceeded in the
primary circuit (3 bar).
It fitted on the front of the pump unit (2) and fixed on the
outside by means of a fork.
When this valve triggers, water exits from the boiler return
pipe.
Expansion vessel (8).
It compensates for variations in volume as a result of heating
the water which also limits pressure variations.
It has a 6-litre capacity (4.5 useful litres) for the 24 model and
7.5 litres (4.5 useful litres) for the 28 model and a preload
pressure of 1.0 bar.
In the 24 model it is rectangular in shape and located on the
right-hand side of the boiler, by the side of the combustion
chamber while, in the 28 model it is circular in shape and lo-
cated at the rear of the boiler, behind the combustion chamber;
in both models a copper pipe connects the expansion vessel
to the pump unit (2).
8
4
1
2
3
5
6
7
2
8
NIKE Mini 24
NIKE Mini 28

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Safety devices and checks for S models (central
heating only).
Automatic system by-pass (3).
is device guarantees the circulation of water in the central
heating circuit even when it would be prevented by the high
resistance of the system.
It works between the central heating delivery and return,
inserted inside the by-pass fitting (4) that connects the pump
unit (2) to the delivery manifold.
System filling unit (7).
is is a valve positioned between the boiler circuit and the
domestic cold water inlet and makes it possible to pressurise
the heating system.
e filling up unit is connected to the cold water inlet coupling
(6) by means of a threaded fitting and to the pump unit (2)
by means of an O ring.
Automatic air vent (1).
It automatically expels any gaseous substances there might be
in the boiler circuit.
It is mounted on the circulator delivery, directly on the pump
unit (2).
3-bar safety valve (5).
is valve prevents the safety pressure being exceeded in the
primary circuit (3 bar).
It is fitted at the front of the pump unit (2) and fixed on the
outside with a fork.
When this valve triggers water exits from the boiler return
pipe.
Expansion vessel (8).
It compensates for variations in volume when the water is
heated and also limits pressure variations.
It has a 6-litre capacity (4.5 useful litres) for the 24 S model
and a preload pressure of 1.0 bar.
It is rectangular in shape and located on the right of the boiler,
by the side of the combustion chamber and connected to the
pump unit (2) with a copper pipe.
Note: NIKE Mini 24 S is a wall-hung boiler for central heat-
ing only but by using the optional kit consisting of a 3-way
electric valve and domestic hot water probe (together with the
necessary wiring), it can be combined with a separate storage
tank for producing domestic hot water.
8
4
1
2
3
5
NIKE Mini 24 S
6
7
2

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Operation.
When domestic hot water is drawn cold water flows inside
the d.h.w. flow switch (1) which closes the electrical contact
coupled to it (see the electrical circuit).
As a result, the integrated board starts the d.h.w. priority phase
that ignites the burner and, if there’s an ongoing central heating
request, switches the 3-way diverter valve (2) moving it into the
working position (see operation of the hydraulic 3-way valve).
is causes the delivery pipe (M) to close and simultaneously
the passage opens to the d.h.w. exchanger (3).
In this way circulation in the central heating system is pre-
vented while it is allowed in the plate exchanger, inside which
the domestic cold water absorbs the heat from the primary
circuit water (see d.h.w. exchanger).
So in this phase, central heating is off, domestic hot water
having priority.
e water/water heat exchange occurs inside the d.h.w. ex-
changer (3) which is secured to the d.h.w. inlet (1) and outlet
(2) body with screws.
e top of the body on the left allows cold domestic water to
enter, while at the bottom it allows primary circuit return.
In the same way, the top part of the body on the right allows
the outlet of domestic hot water while at the bottom it allows
primary circuit delivery.
Cold water
inlet
1
3
2
Primary
circuit delivery
Primary
circuit return
D.h.w. outlet
D.h.w. outlet
Secondary circuit (domestic hot water circuit) for combi versions only.

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1
1
Primary
circuit
delivery
Primary
circuit
return
D.h.w. flow switch (2).
Whenever domestic hot water is drawn at a rate of at least 1.5
l/min and a dynamic pressure of 0.3 bar, the flow switch (2)
enables the boiler to work in the d.h.w. mode.
is is done by means of a magnet that, lifting when hit by the
flow of domestic cold water, moves near to an electrical contact
(reed relay) causing it to move thanks to the magnetic effect.
When the contact closes, which is located outside the pipe
through which the water flows, it enables the adjustment board
to start the domestic hot water priority phase.
It consists of two parts (one in brass and one in plastic) that are
coupled together and locked with a pin.
A G1/4” thread on its body connects it to the filling unit
(3).
An 7.1 l/min (2 bar) for model 24 and a 9.2 l/min (2 bar) flow
limiter (1) for model 28 is installed at the flow switch exit.
D.h.w. exchanger.
It is a water-water exchanger made of stainless steel plates one
on top of the other - 12 (for model 24) and 14 (for model 28)
- on whose surface the boiler circuit water and the domestic
cold water flow in counter current and through which the heat
exchange takes place between the two lots of water.
e hydraulic coupling is done using four O rings (1) so it
can be connected directly to the d.h.w. inlet body and to the
d.h.w. outlet body.
D.h.w.
outlet
Cold
water
inlet
Cold
water inlet
1
2
3

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e circuit consists of an atmospheric burner and a modu-
lating gas valve for gas combustion and flow rate regulation
respectively.
Operation.
When the main coils (3) are energised both the inner valve
shutters open allowing gas to flow through to the burner.
e flow rate/outlet pressure is regulated by means of the gas
valve stabiliser via the modulation coil (1).
By means of the burner (7) nozzles the fuel is injected into
the horizontal Venturi tubes (ramps) inside which an optimum
air-gas mixture is obtained that is ignited by the spark of the
ignition electrode (5).
Modulating gas valve.
en gas valve (Honeywell VK 4105 o SIT 845) is equipped
with two main safety coils (3) and one for modulation (1);
they are managed by the printed control board.
Maximum and minimum outgoing pressure adjustments are
to be performed on the gas valve (see gas pressure adjustment
section).
Main electric coils (3).
e two coils are ON-OFF type, they are powered (230
Volts) by the printed control board when the burner is to be
ignited.
In SIT 845 valve, they are electrically connected in parallel
and powered by the power main tension via a relevant con-
nector (2).
Gas circuit.
In Honeywell VK 4105 valve, they are connected in series and
powered by electric main tension rectified by a diode bridge
(U1) located inside the connector (2) (see electric layout).
Modulating coil (1).
is is a low voltage coil controlled by the integrated board.
It controls the gas valve stabiliser and allows the outlet pres-
sure to be varied in a way proportionate to the DC current
running through it.
Burner.
e burner consists of horizontal Venturi pipes (6) inside which
the gas is injected by the same number of nozzles (7) mounted
on the manifold (8).
e number of nozzles, whose diameter varies according to
the type of gas utilised (see technical data) are 12 (24 version)
and 14 (28 version).
Ignition occurs thanks to a p.c.b. that controls both the igni-
tion (5) and detection (4) electrodes.
Ignition electrode (5).
It is controlled by the integrated board that produces an elec-
trical charge between its end and the burner surface, igniting
the air-gas mixture when they come into contact.
It is located at the front of the burner, by the centre ramp.
Detection electrode (4).
It is controlled by the integrated board and detects burner
ignition.
It is located at the front of the burner on the same ramp as
the ignition electrode.
1
3
2
1
2
3
SIT 845
VK 4105