Immergas MAIOR EOLO 4 E Series Guide

MAIOR EOLO 4 E
Instantaneous wall-hung
boilers, sealed-room
with "Aqua Celeris" system
MAIOR EOLO 4 E

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MAIOR EOLO 24-28-32 4 E
Wall-mounted boiler with fan-assisted sealed
combustion chamber for central heating and
instantaneous domestic hot water production,
equipped with AQUA CELERIS system
MAIOR EOLO 24 4 E
MAIOR EOLO 28 4 E
MAIOR EOLO 32 4 E
MAIOR EOLO 4 E is a wall-mounted, sealed chamber,
fan-assisted generator (type C) for central heating and the
production of domestic hot water.
e boiler can be installed according to conguration B22 using
the relevant kit (optional).
e boilers in the MAIOR EOLO 4 E range are approved for
installation outside buildings in a partially protected location.
N.B.: A partially protected location is a place where the appliance
is not exposed to the direct eects of the weather (rain, snow, hail,
etc...).
e appliance is available with eective outputs of 24 kW
(20.640 kcal/h), 28 kW (24.080 kcal/h) and 32 kW (27.520
kcal/h).
Adjustment and control are entrusted to an integrated P.C.B.
with micro processor with continuous ame modulation by
means of 2 sensors (domestic water and central heating).
e new electronics allow the new Comando Amico Remoto
remote control (CAR V2) to be connected so that the boiler
can be managed and controlled remotely with extreme ease;
it is also designed for systems that are subdivided into zones
and to be connected to the new Multi-system Distribution
Manifolds (DIM V2).
e boiler has a standard anti-freeze safety devicethat protects
it to a minimum temperature of -5°C (optional to -15°C).
e hydraulic circuit has a bronze water-gas heat exchanger
and uses a new multi-purpose hydraulic unit made from
composite material (ICHS) which houses the pump and
3-way electric valve that allow the boiler water to circulate in
the CH system or in a STAINLESS steel plate heat exchanger
General features
for the instantaneous production of DHW according to
necessity, as well as the hydraulic circuit control devices
(absolute system pressure switch, adjustable system by-pass, 3-bar
calibrated system safety valve, etc.).
A domestic water ow switch allows the boiler to be activated
when domestic hot water is requested.
The range features the "Aqua Celeris" system, which
drastically reduces wait times for domestic hot water supply.
e boiler is deisgned to receive pre-heated water from a solar
storage tank; by activating this function through the boiler
parameters, the burner and the boiler turn on only if necessary
in order to reach the set domestic hot water set point.
e intake of combustion air inside the sealed chamber and
ue extraction are ensured by a fan which is guaranteed to
operate correctly by means of a dierential ue pressure switch.
e parameters to operate the boiler can be set by rotating
the knobs where you can view the operating status, mode and
anomalies that have occured using a digital interface with an
easy-to-read backlit display screen, located in the centre of
the dashboard.
e appliance has an IPX5D electric insulation rating: this
means that the boiler is protected against jets of water and
high humidity levels.

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Main MAIOR EOLO measurements and connections
Key:
V - Electrical connection
G - Gas supply
AC - Domestic hot water outlet
ACV- Solar valve kit DHW inlet
(Optional)
AF - Domestic cold water inlet
R - System return
M - System ow
Height
(mm)
Width
(mm)
Depth
(mm)
781 440 340
CONNECTIONS
GAS
DOMESTIC
HOT
WATER
SYSTEM
GAC AF R M
3/4” 1/2” 1/2” 3/4” 3/4”
N.B.: connection group (optional)

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MAIOR EOLO controls panel
Key:
1 - Heating temperature selector
2 - Domestic hot water temperature
selector
3 - On/Stand-by/O Button
4 - Summer/Winter Button
5 - Reset Button
6 - Boost Button for Aqua Celeris
activation
7 - Operation in summer mode
8 - Boiler in Stand-by mode
9 - Operation in winter mode
10 - Blocked boiler, it needs to be
unblocked by pressing the “RESET”
button
11 - Flame presence symbol and relative
output scale
12 - Central heating room phase function
active
13 - Solar function active
14 - Anomaly present
15 - Chimney sweep function in progress
16 - DHW production phase function
active
17 - Domestic hot water temperature set
18 - Boiler connected toV2 remote
control (optional)
19 - Operation with external
temperature probe active (optional)
20 - Aqua Celeris function active
21 - Central heating temperature set
22 - Boiler manometer

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Main MAIOR EOLO parts
Key:
1 - Sample points (air A) - (ue gases F)
2 - Sealed chamber
3 - Fan
4 - Combustion chamber
5 - Domestic hot water ow switch
6 - Gas valve
7 - Domestic hot water probe
8 - System lling valve
9 - Positive signal pressure point
10 - Negative signal pressure point
11 - Flue pressure switch
12 - Flow probe
13 - Flue hood
14 - Safety thermostat
15 - Primary heat exchanger
16 - Ignition and detection electrode
17 - System expansion vessel
18 - Aqua Celeris
19 - Burner
20 - System pressure switch
21 - Air vent valve
22 - Boiler pump
23 - Plate heat exchanger
24 - 3-way valve (motorised)
25 - System draining valve
26 - By-pass
27 - 3 bar safety valve
N.B.: connection group (optional)

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e hot water used for central heating and domestic hot water
is produced via a primary and a secondary circuit (DHW)
which are aected according to necessity.
MAIOR EOLO hydraulic diagram
Key:
1 - Domestic hot water ow switch
2 - System lling valve
3 - Flow limiter
4 - Domestic hot water probe
5 - Aqua Celeris Resistance
6 - Gas valve
7 - Aqua Celeris
8 - System expansion vessel
9 - Burner
10 - Primary heat exchanger
11 - Flue hood
12 - Sealed chamber
13 - Flue pressure switch
14 - Fan
15 - Flow probe
16 - Safety thermostat
17 - Air vent valve
18 - Boiler pump
19 - System draining valve
20 - System pressure switch
21 - Plate heat exchanger
22 - 3-way valve (motorised)
23 - By-pass
24 - 3 bar safety valve
G - Gas supply
AC - Domestic hot water outlet
AF - Domestic hot water inlet
R - System return
M - System ow

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Primary circuit (boiler circuit).
e primary circuit, with relative control and safety devices,
starts up every time there is a central heating or domestic
hot water request.
How it works (see MAIOR EOLO)
e heat contained in the ue produced by combustion is
absorbed by the copper blades of the water-air heat exchanger
(10) which, then transfers the heat to the water that circulates
inside by the boiler pump (18).
e water is either sent directly into the system or it can be
deviated inside the STAINLESS steel instantaneous plate heat
exchanger (21).
Head (kPa)
Flow rate Litres/h
A = Head available to the system at maximum speed with by-pass excluded.
B = Head available to the system at maximum speed with by-pass inserted.
C = Head available to the system at second speed with by-pass excluded.
D = Head available to the system at second speed with by-pass inserted.
Head (m H2O)
MAIOR EOLO 24
Head (kPa)
Flow rate Litres/h
Head (m H2O)
MAIOR EOLO 28
is depends on the position of the 3-way motorised valve (22),
which allows ow towards the domestic water heat exchanger
(21) in its resting position, or deviates it towards the ow (M)
and return (R) pipes following a request for central heating.
Head-ow rate graphics
e progress of the curve that represents the ow rate-head ratio
available to the system depends on the operating speed of the
pump and adjustment of the system by-pass which, according
to the position, allows you to set more or less head on the
system. e graph below illustrates the characteristic curves.
A
B
C
D
A
B
C
D

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A = Head available to the system at maximum speed with by-pass excluded.
B = Head available to the system at maximum speed with by-pass inserted.
C = Head available to the system at second speed with by-pass excluded.
D = Head available to the system at second speed with by-pass inserted.
MAIOR EOLO 32
Head (m H2O)
Head (kPa)
Flow rate Litres/h
A
B
C
D

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Boiler pump (1)
Operates on the primary circuit return. It is part of the pump
body unit made with composite material.
ere is a seat built into the body 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 counter-clockwise by a quarter turn.
Primary Exchanger (1)
is is a lamellar water-gas heat exchanger with bronze pipes
and ns that have the central heating ow NTC probe (6)
and the overheating safety thermostat (2) positioned on their
outlet (ow).
e four pipes that it is made of are connected in series (1).
It is connected to the pump ow and to the primary circuit
ow using push-tting pipes (3) with O.R. seal (5) and locked
with clips (4).
e heat exchangers for versions 24, 28 and 32 dier in their
number of ns (86 ns in version 24) (89 ns in version 28)
(104 ns in version 32), and also for the dierent arrangement
for ow and return (see picture below).
1
34
5
2
6
Flow
Return
1
34
5
2
6
MAIOR EOLO 24
Flow
Return
MAIOR EOLO 28 - 32
1
2

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FLOW
HEAT EXCHANGER
FLOW
SYSTEM
FLOW
HEAT EXCHANGER
DHW
Motorised 3-way valve
is is composed of an electric motor (1) connected to the
three-way group (2) with a clip.
Based on the request (DHW or CH), the three-way clip allows
boiler water to enter the heating system or in the DHW (plate)
heat exchanger.
is depends on the position of the shutter (4) which closes
the passage to the system and at the same time opens the
passage to the DHW heat exchanger (DHW position), or vice
versa (CH position).
e motor (1) is operated by the P.C.B. and moves the shutter
(4) in both positions.
e hydraulic part is made of a group built with composite
material (2).
Operation during the heating phase
e counter spring (3) for the shutter (4) is not compressed
(heating position), keeping the passage towards the DHW
(plate) heat exchanger closed and the passage towards the
system ow open.
Both the spring (3) and the shutter (4) are situated inside the
body of the 3-way cartridge made from composite material (2).
Operation in domestic hot water phase
e hydraulic group is kept in the DHW phase position.
e electric motor (1) pushes the stem (5) that the shutter is
attached to (4), closing the passage towards the system, and at
the same time opening the passage towards the DHW (plate)
heat exchanger, compressing the counter spring (3) for the
shutter (4) (DHW position).
Both the spring (3) and the shutter (4) are situated inside the
body of the 3-way cartridge made from composite material (2).
Flow
heat exchanger
Return
heat exchanger
1
2
5
4
3
Flow
heat exchanger
DHW
Flow
system

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Safety devices and controls
Adjustable system by-pass (5)
is guarantees circulation in the CH circuit even when the
high resistance of the system does not allow it.
It operates between the ow and return of the CH circuit.
It is push-tted into the top of the pump group (3) and is
locked with a clip. It is accessible from the front of the pump
group itself and can be adjusted using a screwdriver.
System lling unit (7)
is is a pin valve positioned between the boiler circuit and
the domestic cold water inlet that enables the CH system to
be placed under pressure.
e valve is connected to a manifold (6) which is in turn
connected to the cold water input and the pump group with
a locking clip.
System pressure switch (1)
It detects the pressure inside the primary circuit.
Its seat is built into the pump group (3) and is coupled to a
micro switch that prevents the burner from operating when
the detected pressure is below 0.3 bar.
It prevents the primary heat exchanger from overheating.
Automatic air vent valve (2)
is allows the gaseous substances that may be present in the
boiler circuit to be automatically expelled.
It is mounted on the pump ow directly on the pump group
(3).
3 bar safety valve (4)
is prevents the primary circuit from exceeding the safety
pressure (3 bar).
It is push-tted into the front part of the pump group (3) and
is attached to the external side using a clip.
Its intervention causes water to leak from the boiler return.
System expansion vessel (8)
It compensates the variations in volume caused by heating the
water, thus limiting the pressure variations.
It has a capacity of 7.5 litres (eectively 6.8 litres) and a factory-
set pressure of 1.0 bar.
It is positioned at the rear of the appliance and is connected
to the pump group with a bronze pipe. 8
5
12
3
4
7
6

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Multipurpose Hydraulic Group ICHS
Before replacing the various components found on the ICHS
unit, the water present inside the primary circuit must be
drained by unscrewing the system draining tting.
Before draining, ensure that the system lling valve is closed.
ree-way valve cartridge replacement
To replace the 3-way cartridge (1) slide the locking clip out (2)
and extract the small electric motor (3) and then using a CH
28 key turn the cartridge counter-clockwise so that it detaches
from the composite body (8).
N.B.: when you are re-attaching the cartridge you must be very
careful not to damage the relative O-ring seal.
Pump motor replacement
To replace the pump body, remove the 4 screws (14) that attach
the motor (13) to the composite body (12).
Replacement of the automatic air vent valve
To remove the air vent valve from the pump body, turn the air
vent valve counter-clockwise by a quarter turn, being careful
not to damage the relative O-ring seal.
N.B.: when re-mounting the air vent valve, pay particular
attention to inserting the relative O-ring correctly.
6
14
1
9
8
10
5
4
3
2
12
13
11
7
By-pass cartridge replacement
To replace the by-pass cartridge (5) you need to pull out the
relative locking clip (6), and then pull the cartridge out from
the front.
N.B.: when re-mounting the by-pass cartridge body be careful
not to damage the gasket.
3 bar safety valve replacement
To replace the 3 bar safety valve (5) you need to pull out the
relative locking clip (6), and then pull the cartridge out from
the front.
N.B.: when re-mounting the 3 bar valve, pay particular
attention to inserting the relative O-ring correctly.
System pressure switch replacement
To replace the system pressure switch (11), slide the relevant
locking clips out.
N.B.:when re-mounting the system pressure switch, pay
particular attention to inserting the relative O-ring correctly.
Taking out the plate heat exchanger
To take out the plate heat exchanger you need to remove the
two screws (7) that keep the plate heat exchanger fastened (9)
to the hydraulic group (8).
N.B.: when you put the plate heat exchanger back in place
you need to pay close attention to inserting it correctly and
checking the state of the gaskets.

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1
3
2
4
Secondary circuit (domestic hot water circuit)
How it operates
Use of the DHW leads to cold water passing through the ow
switch (1) and the consequent closure of the electric contact
that is coupled to it (see electric circuit).
After this, the integrated P.C.B. starts up the phase for DHW
priority that causes the burner to turn on, and if a CH request
is in underway, it also starts up the deviation of the 3 way valve
(2) which subsequently moves to the work position (see how
the 3 way hydraulic valve operates).
is causes the ow pipe (M) to close and simultaneously open
the passage towards the DHW heat exchanger (3).
In this way circulation in the CH system is blocked while it is
enabled in the plate heat exchanger (3), whose exit (primary
side) is connected to the AQUA CELERIS tank, where the
pump draws out pre-heated water before sending it to the
main heat exchanger.
is allows cold domestic water to absorb the heat contained
in the water of the primary circuit even before the burner
operates at full working capacity (see domestic water exchanger)
and reduce the typical downtimes of instantaneous boilers.
e CH phase is excluded in this phase and priority is given
to the production of DHW.
e water/water heat exchange occurs inside the domestic
water heat exchanger (3) which is screwed onto the body of
the domestic water inlet (1) and the body of the domestic
water outlet (2).
e upper left part of the body allows cold domestic water to
enter, while the lower part allows the return of the primary
circuit to the main heat exchanger by rst passing through the
AQUA CELERIS tank.
In the same way the upper part right part of the body allows
DHW to ow out and the lower part allows the primary
circuit to ow.
Domestic cold
water inlet
Flow
primary circuit
Return
primary circuit
Water outlet
DHW
Water outlet
DHW
Flow
Aqua Celeris
Output
Aqua Celeris
Aqua Celeris inlet

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Aqua Celeris device (4)
is is a tank (that contains water from the primary circuit) with
a capacity of 2 litres, insulated with styrofoam and is designed
specically to reduce DHW supply times.
In the lower part there are two threaded 3/4"G ttings with
a gasket seal (inlet and outlet of the primary circuit), where the
ow and return of the primary circuit occur.
e lower part also houses the electric resistance PTC (8).
From the tting (7) the water coming from the plate heat
exchanger is directed into the tank.
From the probe pipe (5) the water inside the tank is drawn
out by the vacuum created by the action of the boiler pump
and sent back to the primary heat exchanger.
Once ow has ceased, the water inside is kept warm with a
special PTC electric resistance with timer (8) that supplies
the water with the amount of heat that is strictly necessary to
restore the loss of heat by dispersion.
In the top part there is a manual vent valve (6) which is used
to expel any gaseous substances contained inside the primary
circuit.
7
4
8
6
5
Flow
circuit
primary
Return
circuit
primary

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Hydraulic connection to the Aqua Celeris
device
e hydraulic group (4) makes the hot ow water coming
from the primary heat exchanger ow through the plate heat
exchanger rst (3). At the outlet of the plate heat exchanger, by
owing through the pipe (2), the water collects inside the aqua
Celeris tank (1), and is then drawn out by the boiler pump (1)
which is connected to the Aqua Celeris tank with a pipe (6)
and sent back to the primary heat exchanger.
3
5
1
2
4
6

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DHW ow switch (1)
With respect to drawing DHW with a ow rate of at least 1.5
l/min and a dynamic pressure of 0.3 bar, the ow switch (1)
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 outside the
pipe where the water passes, allows the integrated modulation
P.C.B. to start the DHW priority function mode.
It is made up from two parts (one in brass and one in plastic)
that are coupled and locked with a pin.
A lter (2) is lodged inside of it.
It is attached with two screws to the body of the DHW inlet
(4), which, in turn, the system lling group is connected to.
A (2 bar) 7.1 l/min ow rate limitor (3) is inserted at the ow
switch outlet for model 24, 9.5 l/min (2 bar) for model 28
and 11.8 l/min (2 bar) version 32.
DHW heat exchanger
is is a water-water heat exchanger compsed of STAINLESS
steel plates laid one on top of another, 12 (for model 24), 14
(for model 28) and 16 (for model 32) where the water from the
boiler circuit and cold domestic water ows pver their surfaces,
against the ow, and where the heat exchange occurs between
the two liquids.
e hydraulic coupling is obtained by using four gasket seals
(1) that allow it to be connected directly to the domestic water
inlet body and domestic water outlet body.
1
1
Domestic cold
water inlet
Flow
circuit
primary
Return
circuit
primary
Output
water
hot
domestic
water
Inlet
water
cold
domestic
water
1
2
3
4

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e circuit is composed of an atmospheric burner and a
modulating gas valve, which respectively allow the combustion
of the gas and the adjustment of its ow rate.
How it operates
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 (SIT 845)
e gas valve is equipped with two main coils (3) and a
modulation coil (1) controlled by the integrated P.C.B.
The maximum and minimum outlet pressure values are
calibrated 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 by the
mains voltage through a specic connector (2).
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.
Gas circuit
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
Standard values for the boiler at maximum capacity
1
3
2
Modulation
coil
Connector
viewed from the
gas valve
EV1
EV2
Common

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7
4
5
6
Burner
e burner is composed of horizontal venturi pipes (5) where
gas is injected by the same number of nozzles (6) mounted on
the specic manifold (7).
e number of nozzles, whose diameter varies according to
the type of gas being used (see technical data), there are11 for
versione 24, 13 for version 28 and 15 for version 32.
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.
Note: for correct ignition and detection of the boiler always
respect the quotes stated in the gure here to the right.
Required height:
H min = 2.5 mm
H max = 4 mm
Optimal position for the electrode for
correct detection

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Gas adjustments
The minimum and maximum pressure adjustments are
performed by acting on the gas valve and must be carried
out respecting the values stated in the tables relative to each
generator for the corresponding type of gas (see technical data).
e measurement is made using a dierential manometer
whose positive pressure point is connected to the gas valve
outlet (4) and to the positive pressure point present in the
ange with sample points connected on the upper part of the
sealed chamber (see gure).
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
Draw DHW after having positioned the temperature dial on
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
(this must be done after you have adjusted the maximum
pressure) after the power supply has been disconnected from
the modulation coil, turn the screw clockwise (2) to raise the
pressure in the burner and counter-clockwise to lower 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 replacing the nozzles on the
burner and selecting the parameter for the type of gas (S2) on
the boiler push button panel; then select (nG) for Methane
or (lG) for L.P.G.
e maximum and minimum DHW pressures are adjusted
on the gas valve in the manner described above.
e adjustments of the minimum and maximum outputs in
CH mode can be set using parameters (see integrated P.C.B.
functioning).
e ignition pressure for the burner can be adjusted and
set using the "Ignition Output" (S4) parameter with the
same value as "Minimum heating output" (see Operating the
integrated P.C.B.).