Immergas ZEUS Maior User manual

ZEUS
Maior @
Wall-hung, room sealed boilers
with storage tank
ZEUS Maior @

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ZEUS Maior @
Wall-hung, room-sealed, fan-assisted boiler
with storage tank
ZEUS 21 Maior @
ZEUS 24 Maior @
General features.
ZEUS Maior @ is a wall-hung room-sealed fan-assisted boiler
(type C) with a storage tank for central heating and producing
domestic hot water.
 is boiler can be also be installed in the B22 confi guration by
using the (optional) kit.
It is equipped with an AISI 316 L stainless steel coil type stor-
age tank, with a total capacity of 60 litres, and a 2-litre d.h.w.
expansion tank (standard feature).
 is boiler is available with an output power of 21,000 kcal/h
(24.4 kW) and 24,000 kcal/h (27.9 kW) with an operation
performance higher than 90%.
Both versions feature electronic control of the ignition, tem-
perature and fl ame modulation.
With the new electronics used this boiler can be connected to
the Remote Control used for maximum simplicity.
 e hydraulic circuit is equipped with a copper water-gas
exchanger and uses the new hydraulic power unit made in
a composite material and where we fi nd the hydraulic circuit
control devices (absolute system pressure switch, adjustable system
by-pass, etc...) besides the circulator and electric 3-way diverter
valve that, according to requirements, allow boiler water to
circulate through the heating system or through the storage
tank coil to produce domestic hot water.
Combustion air intake inside the airtight chamber and the
expulsion of gases are ensured by a fan. A diff erential fl ue
pressure switch controls correct fan operation.

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Main dimensions and connections.
Legend:
G - Gas supply
R - System return
M - System delivery
RC - Recirculation (optional)
U - Hot water outlet
E - Cold water inlet
V - Electrical supply
Control panel.
Legend:
1 - Central heating selector switch
2 - Domestic hot water selector switch
3 - Burner ON yellow indicator light
4 - Boiler ON green indicator light
5 - Domestic hot water/Remote Control-Domestic Hot Water
and Central Heating-Reset Switch 0
6 - Boiler shutdown red indicator light
7 - Boiler thermometer
8 - Boiler manometer
Height (mm) Width (mm) Depth (mm)
900 600 450
CONNECTIONS
GAS SYSTEM D.H.W.
G R M U E
1/2” 3/4” 3/4” 1/2” 1/2”

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ZEUS Maior @ main components.
Legend:
1 - Testing holes (A air) - (F flue)
2 - Flue pressure switch
3 - Central heating delivery NTC probe and limit
4 - Primary exchanger
5 - Overtemperature safety thermostat
6 - Combustion chamber
7 - Automatic air vent
8 - Circulator
9 - Gas valve
10 - Motorised 3-way diverter valve
11 - System draining cock
12 - System filling valve
13 - Airtight chamber
14 - Draught diverter
15 - System expansion tank
16 - Ignition/detection electrodes
17 - Burner
18 - Domestic hot water NTC probe
19 - 316L stainless steel storage tank
20 - System water pressure switch (absolute)
21 - System 3-bar safety valve
22 - D.h.w. 8-bar safety valve
23 - Storage tank draining cock
24 - Fumes expulsion fan
25 - Pressure point, positive signal
26 - Pressure point, negative signal
27 - D.h.w. expansion tank
28 - Adjustable by-pass

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Hot water for central heating and domestic use is produced
by a primary and a secondary (d.h.w.) circuit that work as
required.
ZEUS Maior @ Hydraulic diagram.
Legend:
1 - Gas valve
2 - Stainless steel coil for the storage tank
3 - Magnesium anode
4 - Storage tank
5 - Automatic air vent
6 - Main burner
7 - Combustion chamber
8 - Primary exchanger
9 - Draught diverter
10 - Fumes expulsion fan
11 - Flue pressure switch
12 - Airtight chamber
13 - Central heating delivery NTC probe e limit
14 - Overtemperature safety thermostat
15 - Expansion tank
16 - Circulator
17 - Adjustable by-pass
18 - System water pressure switch (absolute)
19 - System draining cock
20 - Motorised 3-way diverter valve
21 - Domestic hot water NTC probe
22 - 3-bar safety valve
23 - Filling valve
24 - D.h.w. expansion tank
25 - 8-bar safety valve
26 - One-way valve
27 - Storage tank draining cock
R - System return
M - System delivery
G - Gas supply
U - Domestic hot water outlet
E - Domestic cold water inlet

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A = Head available to the system at top speed with the by-pass off
(adjustment screw tightened right down)
B = Head available to the system at top speed (screw tightened 1.5 turns
compared to the adjustment screw which is completely unscrewed)
C = Head available to the system at top speed with the by-pass open
(adjustment screw completely unscrewed)
Primary circuit (boiler circuit).
e primary circuit, with its control and safety devices, is
started each time either a central heating or domestic hot
water request is made.
Operation.
e heat contained in the fumes produced by combustion is
absorbed by the copper blades of the water-gas exchanger (8)
which, in turn, transfers it to the water circulating inside by
means of the boiler circulator (16).
e water is transferred directly to the system or it can be devi-
ated to the storage tank coil (2). is depends on what position
the electric 3-way diverter valve (20) is in which, according to
the request, either lets water flow through the system delivery
(M) and return (R) pipes or to the coil (2).
Head-flow rate graph.
e course of the curve that represents the flow rate/head ratio
depends on how the system by-pass is set which, according to
the position, gives the system a bigger or smaller head. e
characteristic curves, based on the by-pass setting, are shown
in the following graph.
Boiler circulator (1).
e pump works on the primary circuit immediately after the
3-way diverter valve to which it is connected. It is part of the
integrated multifunction unit made in a composite material.
e automatic air vent (2) is housed on the body.
Primary exchanger (1).
is is a lamellar water-gas exchanger with copper tubes and
fins (96 fins in the ZEUS 21 version and 109 in the ZEUS 24
version) and at whose outlet (delivery) both the central heat-
ing NTC delivery probe (2) and the overtemperature safety
thermostat (3) are located.
e four pipes it is made of are connected in series (4).
It is connected to the circulator delivery and to the primary
circuit delivery by push-fitted pipes (5) and O rings (6) locked
with forks (7).
Head (kPa)
Flow rate Litres/h
A
Head (m H2O)
ZEUS 21 Maior @
Head (kPa)
Flow rate Litres/h
Head (m H2O)
ZEUS 24 Maior @
B
C
A
B
C
Delivery
Return

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Motorised 3-way valve.
It is an electric 3-way diverter valve that works on the primary
circuit return and, according to the request made (d.h.w. or
heating), it lets boiler water into the central heating system or
into the storage tank coil. is depends on the position of the
shutter (5) which closes passage to the system while simulta-
neously opening it to the storage tank (d.h.w. position) or vice
versa (central heating position).
e shutter (5) is shifted into both positions when the motor
(1) is powered (1).
e hydraulic part consists of composite material (2) unit
integrating the circulator and operated by a motor (1) that
shifts it as required.
Operation.
When the central heating or domestic hot water position has
to be reached the adjustment board starts the motor (1).
When it is working, with each 180° rotation, it shifts the shut-
ter (5) and either compresses (central heating position) or releases
(d.h.w. position) the shutter counteracting spring (4).
Both the spring (4) and shutter (5) are inside the 3-way car-
tridge.
e hydraulically controlled reaching of the position requested
causes, alternately, the opening and closing of one of the two
limit microswitches (6) located inside the motor box (1).
is makes it possible to cut power off to the motor, block-
ing it in the position reached and to enable motor operation
only when a different request is made (d.h.w. or central heating
signal).
Circulator
delivery
SYSTEM
RETURN
COIL
RETURN
Storage
tank coil
return
System
return
CIRCULATOR
RETURN

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Safety devices and controls.
Adjustable system by-pass (2).
is device ensures circulation of water in the primary circuit
(between delivery and return) even when this is prevented by
the system’s high resistance.
It is mounted on the delivery manifold unit (1) and can be
adjusted by a screw, accessible from the bottom of the valve
supporting plate.
System filling device (3).
It is a ball cock mounted between the boiler circuit and the
inlet of the domestic cold water and permits pressurisation of
the central heating system.
e cock is connected to a fill-up fitting (4) which, in turn, is
connected to the motorised 3-way diverter valve unit.
System pressure switch (5).
It reads the pressure inside the primary circuit.
It is housed in the delivery manifold unit (1) and coupled to a
microswitch that prevents the burner working when pressure
is below 0.3 bar.
It prevents the main exchanger from overheating.
Automatic air vent (6).
It automatically expels any gaseous substances from the boiler
circuit.
It is mounted on the pump’s delivery side directly on the
hydraulic unit.
3-bar safety valve (7).
is valve prevents the safety pressure (3 bar) being exceeded
in the primary circuit.
It is coupled to the front of the delivery manifold unit (1) and
fixed on the outside by a fork.
When this valve triggers water exits from the delivery pipe.
System expansion tank (8).
It compensates for variations in volume as a result of heating
the water which also limits pressure variations.
It has a useful capacity of 5.9 litres (ZEUS 21 version) and 7.1
litres (ZEUS 24 version) and a pre-load pressure of 1.0 bar.
It is located at the front of the storage tank in front of the
boiler.
8
System
delivery

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Secondary circuit (d.h.w. circuit).
e domestic hot water circuit starts working whenever the
temperature of the water in the storage tank (2) has to be
taken to the value wanted, measured by the d.h.w. NTC
probe (9).
is can happen if some hot water is drawn or when restoring
pressure drops due to heat loss.
Operation.
When domestic hot water is drawn, the modulation board
starts the boiler circulator (7) working and powers the motor
of the electric 3-way diverter valve (8).
When the valve shifts into the d.h.w. position (see operation
of the electric 3-way diverter valve) the system return (R) pipe
closes and simultaneously the passage opens to the storage
tank coil (4).
is prevents circulation in the heating system while it is al-
lowed in the coil (4) which, through its walls, lets the cold water
absorb the heat contained in the primary circuit water.
In this phase the central heating function is off, the production
of domestic hot water having priority.