Immergas Zeus Maior 24 User manual

Zeus Maior 24 Instructions
Instruction Booklet
Wall Mounted, Room Sealed, Gas Fired
Combination Boiler with Unvented Hot Water
Storage
For technical assistance, spare parts or service call:
RVR Limited, Kenmare, Co. Kerry Tel: [phone], Fax: 64 8952
Read these instructions completel before using or installing the Immergas Zeus Maior 24
gas boiler
LEAVE THESE INSTRUCTIONS WITH THE USER
IMMERGAS ZEUS MAIOR 24

Zeus Maior 24 Instructions
Introduction
Boiler Operating Instructions
The Immergas Zeus Maior 24 boiler is a wall mounted, fan assisted room-sealed combination boiler, incor-
porating a 6 litre unvented hot water storage cylinder. Heat output is controlled by a modulating gas valve,
with fully automatic direct burner ignition.
The boiler, providing both central heating and domestic hot water supply, is designed for use with a fully
pumped, sealed and pressurised heating system using Natural Gas or LPG. The boiler is supplied for use
with one of these gas types and must be converted before it can be used on another gas. A oiler
equipped for natural gas must not e used on LPG or vice versa.
The boiler is supplied with a pump, diverter valve, pressure relief valve, expansion vessel and pressure
gauge fully assembled and tested.
As supplied, the boiler will automatically modulate to provide central heating outputs between 1 .5 and
27.9kW. The maximum output available for domestic hot water is 27.9 kW and provides hot water at tem-
peratures of up to 6 °C and flow rates of up to 17 litres/min (at a temperature rise of 6 °C)
IMPORTANT
All gas appliances must be installed by a competent and qualified person, in accordance with relevant
clauses of applicable standards and recommendations. These include but may not be limited to the follow-
ing:-
I.S. 813 Domestic Gas Installations
I.S, 82 Non-Domestic Gas Installations
All relevant Building Regulations.
Local Water Bye Laws
IEE Wiring Regulations
Health & Safety legislation
This appliance meets the requirements of IPX4D, ie degree of protection against moisture.
Failure to install this appliance correctly could lead to prosecution. It is in your own interest and that of
safety to ensure that the law is complied with. Manufacturer's instructions must NOT be taken in anyway as
over-riding statutory obligations.
Key:
1 - Heating temperature selector
2 - Domestic hot water temperature
selector
3 - Boiler over temperature and flue
bloc red indicator
4 - Power On green indicator lamp
5 - Operating mode and Reset switch
6 - Loc out red indicator lamp
7 - Boiler thermometer
8 - Boiler manometer
Using the Boiler
Before lighting, make sure that the system is full of water and that the manometer (8) indicates a pressure
of 1 - 1.2 bar.
-Open the gas valve on the gas supply to the boiler.
-Turn Operating mode switch (5) to Hot Water or Hot Water/Heating.
N.B.: . With the switch set to the central Heating temperature setting (1) is not active, and the domestic
water temperature is controlled by selector (2).
With the switch set to the central heating temperature is set using selector (1) while selector (2) is
used for the domestic hot water. Turn the selectors clockwise to raise the temperature, anticlockwise to
lower it. Boiler operation is now automatic.

Zeus Maior 24 Instructions
PERFORMANCE:
Nominal Heat Input kw 3 .3 (26 3 )
Min. Heat Input kw 12.2 (1 466)
Nominal Heat Output (useful) kw 27.9 (24 )
Min. Heat Output Kw 1 .5 (9 )
GAS: G20 G30 G31
Nozzle diam. mm 1.3 .75 .75
Supply Pressure mbar 2 29 37
HEATING SYSTEM :
Burner Pressure (Nom Output) mbar 1 .5 28.1 36.7
Gas Rate m³/h/kg/h 3.2 2.39 2.35
Max working pressure heating circuit bar 3
Max working temp heating circuit °C 9
Adjustable temp heating °C 43-9
Expansion Tank Total Volume L 8
Expansion Tank preload bar .8
Water contained in boiler L 4
Available head with flow rate 1 /l/h Pa
(mH2O)
29.4 (3. )
DOMESTIC HOT WATER:
Useful heat output hot water production w 27.9
Adjustable temp domestic hot water °C 2 -6
Hot water storage capacity L 6
Continuous hot water flow rate@ ∆T =3 oC l/min 13.9
Boiler weight filled g 138
Boiler weight empty g 74
ELECTRICAL:
Electrical connection v/hz 23 /5
Nominal Absorption A .76
Electrical power W 155
Power absorbed by circulating pump W 9
Power absorbed by fan W 35
Equipment electrical system production - IP44
FLUE GASES: G20 G30 G31
Flue gas production @ nom output g/h 67 69 71
Flue gas production @ min output g/h 71 79 79
CO2 at Q Nom/Min % 6.5/2.3 7.2/2.4 7. /2.4
CO at % O2 at Q Nom/Min ppm 64/1 4 89/112 6 /13
NOx at O% O2 at Q Nom/Min ppm 15 /83 24 /1 8 2 1/1 2
Flue gas temperature at nominal output °C 115 117 12
Flue gas at minimum output °C 85 83 92
DIMENSIONS & INSTALLATION DATA:
Height mm 9
Width mm 6
Depth mm 45
Gas Connection 3/4”
CH Connection 3/4”
DHW Connection 1/2”
Minimum clearances for servicing
Top mm 2
Bottom mm 15
Side mm 1
Front mm 6

Zeus Maior 24 Instructions
Main Boiler Components
Key:
1 Air (A) and Flue(F) connections 14 Flue Extractor Hood
2 Fan Safety Pressure Switch 15 Expansion Tank
3 Heating NTC limit and regulation sensor 16 Ignition/Detection Plugs
4 Primary Heat Exchanger 17 Domestic Circuit NTC sensor
5 Combustion Chamber 18 Over temperature Safety thermostat
6 Burner 19 Boiler 316L stainless steel
7 Circulating Pump 2 Domestic Circuit 8 Bar Safety Valve
8 Gas Valve 21 Boiler Drain Valve
9 Motor operated 3-way valve 22 Flue Extraction Fan
1 Circulating pump safety flow switch 23 Positive Signal pressure socket
11 System Filler Cock 24 Negative Signal pressure socket
12 Sealed Chamber 25 System 3 Bar Safety Valve
13 Air Vent Valve 26 System drain cock
Gas CH
Return
CH
Flow
Hot Water
Out
Cold Water
In

Zeus Maior 24 Instructions
Gas Suppl
The meter and supply pipes must be sized to deliver the gas rate and pressure given on page 3. The
boiler requires at least a 22 mm (3/4”) gas supply pipe.
The complete installation, including the meter, must be tested for gas soundness and purged as described
in IS 813:2 2.
Electrical Installation
The boiler requires a 23 V ~ 5 Hz mains supply, fused at 2 A. Polarity of the supply must not be reversed
or the boiler will not function properly. The boiler will not function properly and may be damaged when con-
nected to a generator which does produce a true sine wave type output.
The oiler must e earthed.
There must only be one common isolator, providing complete electrical isolation, for the boiler and any ex-
ternal controls.
Using PVC insulated cable not less than .75 mm² (24 x .2 mm) to BS 65 Table 16, the boiler should be
connected to a fused three pin plug and unswitched shuttered socket outlet (both complying with BS 1363),
or a fused double pole switch with a contact separation of at least 3 mm in both poles.
Wiring external to the boiler must be in accordance with the current IEE Wiring Regulations.
General Installation Information
Zeus Maior Control board
35 34 33 32
N L E
Brown
Blue
Green/Yellow
Replace link with
volt free contact from CH
controls
NB: Do not connect 220V !
Mains Lead
IMPORTANT:
External controls connected to the oiler must e of the volt free type and are connected to termi-
nals 34 and 35 as shown a ove. Connection of a voltage to any oiler terminals other than the
mains lead will result in destruction of the oiler control panel.
Clearances and Air Suppl
The boiler does not require any air vents for cooling in the room in which it is installed or when installed in a
cupboard or compartment. The minimum clearances for servicing must always be maintained. Please see
table on page 3.
Note: A cupboard or compartment used to enclose the boiler must be designed and constructed specifically
for the purpose.

Zeus Maior 24 Instructions
Note: a flue diaphragm is supplied with the oiler and
must e fitted depending on the flue arrangement.
Select the appropriate diaphragm from the tables below:
Diaphragm Flue length in
metres
Ø 44 - .5
Ø 47 .5 - 1.5
None Over 1.5
Ø 60/100 Horizontal flue s stems
Diaphragm Flue length in
metres
Ø 44 - 3
Ø 47 3 - 4
None Over 4
Ø 60/100 Vertical flue s stems
Diaphragm Flue length in
metres
Ø 44 - 22
Ø 47 22 - 29
None Over 29
Diaphragm Flue length in
metres
Ø 44 - .5
Ø 47 .5 - 3
None Over 3
Diaphragm Flue length in
metres
Ø 44 - 5
Ø 47 5 - 8
None Over 8
Diaphragm Flue length in
metres
Ø 44 - 17
Ø 47 17 - 24
None Over 24
Flue S stem
When the boiler is installed on an external wall, the
standard horizontal concentric 6 /1 flue kit will be
used to flue the boiler. This is shown in the diagram.
A flue diaphragm with a 44mm diameter must be
fitted with this flue arrangement.
Please see the following information on the use of
flue diaphragms. Information on extended flue sys-
tems is given on the following pages.
Flue Systems
Flue diaphragms
Ø 80/125 Horizontal flue s stems
Ø 80/80 separated Horizontal flue
s stems
Ø 80/100 Vertical flue s stems
Ø 80/80 separated Vertical flue s stems

Zeus Maior 24 Instructions
It is often necessary to install a longer flue system to cater for site
conditions. There are several different flue system sizes available
for the Zeus Maior 24 boiler.
Horizontal concentric kit 60 /100
The exhaust pipe (φ 6 mm) is fitted inside the air intake
pipe (φ 1 mm). Connection to the boiler is made using a 9 °
bend (1) which can be turned in any direction and can be connected
to the terminal (2).
Max possible overall length after the first bend (1) is
3 straight and horizontal metres.
Horizontal concentric kit 80 /125
The exhaust pipe (φ 8 mm) is fitted inside the air intake
pipe (φ 125 mm). Connection to the boiler is made using a 9 ° bend
diameter 6 /1 (1) which can be turned in any
direction and connected using the adapter 6 /1 -
8 /125 (2) to the 8 /125 terminal (3).
Max possible overall length beyond the first bend(1) is
7.3 straight and horizontal metres.
Vertical concentric kit 60 /100
The exhaust pipe (φ 6 mm) is fitted inside the
air intake pipe (φ 1 mm). Connection to the boiler is made using
a flange (1) which may be connected to the 6 /1 vertical terminal.
Max possible overall length is 4.7 straight and
vertical metres.
Vertical concentric kit 80 /125
The exhaust pipe (φ 8 mm) is fitted inside the Air intake pipe (φ
125 mm). Connection to the boiler is made using a flange (1). The
adapter 6 /1 -8 /125 (3) is used the connect the 8 /125 terminal
(2). Max possible overall length is 12.2 straight and
vertical metres.
Separated 80/80 flue kit
Both pipes have a diameter of 8 mm. Connections to the boiler are
made using two special flanges for exhaust (1) from the centre pipe
and extraction (2) from one of the two side holes.
Max possible length (extraction + exhaust) is 33 straight horizontal
metres and 41 straight vertical metres.
To prevent condensat on problems, the exhaust p pe should
not be more than 5 m long. Adv ce on prevent on of condensa-
t on s ava lable from RVR L m ted. Please contact us when
des gn ng longer flue systems.
Separated 80/80 insulated flue kit
Both pipes have a working diameter of 8 mm.
Connections to the boiler are made using two special
flanges for exhaust (1) from the centre pipe and
extraction (2) from one of the two side holes.
Insulation is obtained thanks to special seals (3)
whereby an air space can be created by means of a φ
125 mm external concentric pipe.
Max possible length (extraction + exhaust) is 33
straight metres.
To prevent condensat on problems, the exhaust p pe
should not be more than 12 m long
Extended Flue Systems

Zeus Maior 24 Instructions
Each component of the air inlet/flue system has a resistance factor . These are given in the following tables.
The resistance factor varies depending on whether the component in question conveys fresh inlet air or hot
combustion gases. All boilers have a maximum resistance factor of 1 . The sum of all components in the
flue system must not exceed the maximum overall resistance factor of 1 .
Flue calculations for more complex systems

Zeus Maior 24 Instructions
Example:
Flue system consists of 9m of 8 mm air intake pipe with 3 x 9 bends and 6m of exhaust pipe with 2 x 9
bends.
Component Resistances:
Component Resistance Quantit Total
8 mm Intake pipe 2.3 9 2 .7
9 ˚ air intake bend 5 3 15
8 mm Flue pipe 3 6 18
9 ˚ Flue bend 6.5 3 19.5
73.2
Total Flue Resistance
In this case the total resistance of the
system is less than 1 . The flue de-
sign is acceptable.
Care should be taken to insulate the
exhaust flue pipe to ensure that con-
densation is not possible.

Zeus Maior 24 Instructions
Terminal Position Min. Distance
A Directly below an opening, air brick, windows, etc.
B Below gutters, soil pipes or drain pipes
C Below eaves
D Below balconies or car port roof
E From a vertical drain pipe of soil pipe
F From an internal or external corner
G Above ground, roof or balcony level
H From a surface facing the terminal
I From a terminal facing a terminal
J From an opening in the car port (door, window) into dwelling
K Vertically from a terminal on the same wall
L Horizontally from a terminal on the same wall
M Horizontally from an opening, air brick, window etc.
Below horizontally hinged windows where exhaust is directed upwards
Below horizontally hinged windows where exhaust is not directed upwards
3 mm
75mm
75mm
75mm
75mm
75mm
3 mm
6 mm
12 mm
12 mm
15 mm
3 mm
3 mm
3 mm
1 mm
The flue terminal must be exposed to the external air and the position must allow the free passage of air
across it at all times. In certain weather conditions the terminal may emit a plume of steam. Avoid position-
ing the terminal where this may cause a nuisance. If the terminal is fitted within 85 mm of a plastic or
painted gutter or 45 mm of painted eaves or 3 mm of a plastic car port roof, an aluminium shield at least
1 m long should be fitted to the underside of the gutter or painted surface. If the terminal is fitted less than 2
m above a surface to which people have access, the terminal must be protected by a terminal guard.
IMPORTANT— Failure to install flue systems correctly may lead to serious injury or death. Ensure
that:
• The flue slopes slightly towards the outlet by between 1 and 2 degrees to ensure any condensate
moves to the discharge point.
• The flue is adequately supported along it’s length so that it is straight.
• No chemicals, detergents or solvents of any kind are used in the assembly of the flue system. Clean
water may be used as to lubricate seals where necessary.
• The flue is thoroughly tested for leaks after installation.
Boiler Location
The boiler is not suitable for external installation.
The boiler must be installed on a flat vertical wall which is capable of supporting the weight of the boiler.
The boiler can be fitted to or adjacent to a wall comprising of a combustible material without the need for a
special thermal insulation barrier.
The boiler may be installed in any room or internal space, although particular attention is drawn to the re-
quirements of the current IEE Wiring Regulations. Where a room sealed boiler is installed in a room con-
taining a bath or shower, it must not be possible for a person using the bath or shower to touch any electri-
cal switch or boiler control utilising mains electricity.
The boiler may be installed in a cupboard or compartment, provided it is correctly designed for that pur-
pose.
NB: Adequate clearances are required to allow servicing of the oiler. Please see page 3.

Zeus Maior 24 Instructions
The boiler is designed for use in a sealed central heating system. The system should be designed to oper-
ate with flow temperatures of up to 8 °C. When designing the system, the pump head, expansion vessel
size, mean radiator temperature, etc. must be taken into account.
The pressure losses in the system must be compatible with the boiler circulation pump. See pump perform-
ance graph below.
Central Heating System
System volume - The 8 liter expansion vessel incorporated into the boiler is pre-charged to 1. bar and
is suitable for a sealed heating system with a maximum water content of 8 litres (18 gal). Above 8 li-
tres, consideration should be given to fitting an additional expansion vessel fitted in the position shown
on the schematic below. To check correct operation of the expansion vessel(s) the system pressure
should not be more than 2.5 bar when the system is at maximum operating temperature.
The boiler is supplied with the following components built in:-
Central Heating Pressure relief valve - complying with BS 6759 and set to operate at 3 bar. The dis-
charge pipe must be routed clear of the boiler to a drain, so that it can be seen, but cannot cause injury
to persons or property.
A Pressure gauge is included to indicate the pressure of the central heating system.
Important Note: In a central heating system where it is possible to shut off system circulation, such as a
system with zone valves or where all radiators are fitted with thermostatic radiator valves, an external by-
pass should be fitted. An optional automatic bypass is available as an accessory for the Zeus Maior 24
boiler. This may be fitted directly to the boiler central heating flow and return connections.
Pump performance curves

Zeus Maior 24 Instructions
Filling the central heating s stem
The system design pressure (cold) should be set to 1. bar. This pressure is equivalent to a static head of
1 .2 metres of water. Provision should be made to replace water lost from the system. This can be by
manual or automatic means.
Filling of the system must be carried out in a manner approved by the local authority. Where allowed, the
system may be filled via a temporary connection as shown below or by using the integrated filling valve in
the boiler. After filling, always disconnect the flexible hose of the filling loop if used and close the filling
valve in the boiler.
All fittings used in the system must be able to withstand pressures up to 3 bar. Drain taps (to BS 2879)
must be used to allow the system to be completely drained. The heating system should be thoroughly
flushed before the boiler is connected and again after the first heating. If it is necessary to add inhibitor to
Cold water
storage tank
Zeus
Maior
System
drain tap
Lockshield
valve
Radiator
valve Automatic
Bypass Non-Return
Valve
Pressure
Booster
Pump
To cold water outlets
To hot water outlets
The most important components of the system are shown in the diagram below.
• The cold water supply for the water heating side of the system may come from a booster pump or the
cold water mains where this is permitted by the local authority.
• A non-return valve must be installed on the cold feed to the boiler. This prevents expanding hot wa-
ter back-feeding into the cold side of the system.
• An automatic bypass should be fitted in systems where central heating circulation can be shut off. (by
zone valves or thermostatic radiator valves).

Zeus Maior 24 Instructions
Mains water pressurised unvented system are generally not permitted in Ireland. A cold water storage tank
and a pressure boosting pump will normally provide a pressurised cold water supply. The pressurisation
pump should provide a water pressure of between 1 and 3 bar. However, all taps and mixing valves used
with the hot water system must be suitable for operating at a pressure of up to 5.5 bar.
To ensure economic use, the pipe runs between the boiler and taps should be in 15 mm copper pipe and be
as short as possible. Where possible the pipe work should be insulated to reduce heat loss.
Before the cold water supply pipe is connected to the boiler, it should be thoroughly flushed out to avoid the
danger of dirt or foreign matter entering the boiler.
The stored water temperature is adjustable to a maximum of 55°C. In hard water areas this should avoid
possible scale build-up. However, if descaling is necessary contact RVR Limited for guidance.
Unvented Hot Water Storage S stem
The installation is subject to Building Regulations and the Water Bye Laws of the Local Authority.
The Immergas Zeus Maior 24 boiler is supplied with all the components required for a safe and efficient
unvented hot water system. An air cushion which is present at the top of the 6 l storage vessel provides
sufficient expansion for the domestic hot water system. An optional additional DHW expansion kit is avail-
able for situations where the inlet pressure exceeds 3 bar or other situations where the expansion capacity
may not be adequate.
NOTE: In the Du lin City Council area the optional expansion vessel must e fitted to comply with
the approval requirements of the council. The council also requires that the minimum internal di-
ameter of pipes connected to the oiler DHW connections should not e less that 13mm. As 1/2”
thermoplastic pipe does not provide the minimum diameter, the minimum suita le thermoplastic
pipe size is 3/4”
Discharge pipe - The discharge pipes from the expansion relief valves must be routed to a tundish in
1/2” (or 15 mm )pipe. The discharge pipe work from both relief valves may be joined together in the same
sized pipe, providing at least 3/4” (or 22 mm) pipe work is connected downstream of the tundish.
Tundish - The tundish must be positioned within 5 mm of the appliance, so that it is visible to the User
and away from electrical devices. The minimum size of the discharge pipe downstream of the tundish is
given in the following table.
Zeus Maior Boiler
Booster
pump
Cold
Water
Supply
Optional
Expansion
Vessel Primary
expansion
valve
DHW
expansion
valve
Divertor
Valve
Expansion volume
Tundish
Check
Valve
Domestic Hot Water System
15mm (1/2”)
22mm (3/4”)
28mm (1”)
35mm (11/4”)

Zeus Maior 24 Instructions
The discharge pipework from the tundish:-
1. Shall fall continuously through its length.
2. Shall be of a heat resistant material, e.g. metal.
3. Shall not be fitted with any valves or taps.
4. Shall discharge to a safe visible position, e.g. onto the surface of an external wall or into a gulley.
5. Shall have a minimum of 3 mm straight pipe work directly from the tundish.
Note: Where children may play or otherwise come into contact with discharges, a wire cage or similar
guard must be positioned to prevent contact whilst maintaining visibility.
Please see the diagrams below for suggested methods of terminating the discharge pipe safely. Where a
single pipe serves a number of discharges, such as in blocks of flats, the number served should be limited
to not more than 6 systems so that any installation can be traced reasonably easily. The single common
discharge pipe should be at least one pipe size larger than the largest individual discharge pipe to be con-
nected. If the system is installed where discharges from safety devices may not be apparent, i.e. in dwell-
ings occupied by blind, infirm or disabled people, consideration should be given to the installation of an
electronically operated device to warn when discharge takes place.
High Level Termination
At high level, discharge onto a roof is acceptable pro-
viding the roof is capable of withstanding high tem-
peratures and there is a distance of 3 m from any
plastic guttering systems that would collect such dis-
charge.
Example:-
The example below is for a G½ temperature relief valve with a
discharge pipe (D2) having four elbows and a length of 7 m from the
tundish to the point of discharge.
From Ta le :-
Maximum resistance allowed for a straight length of 22 mm copper discharge pipe (D2) from a G½ tempera-
ture relief valve is 9 m. Subtract the resistance for four 22 mm elbows of .8 m each = 3.2 m. Therefore the
maximum permitted length equates to 9 - 3.2 = 5.8 m
5.8 m is less than the actual length of 7 m therefore calculate the next largest size.
Maximum resistance allowed for a straight length of 28 mm pipe (D2) from a G½ temperature relief valve
equates to 18 m.
Subtract the resistance for four 28 mm elbows at 1. m each = 4 m.
Therefore the maximum permitted length equates to 18 - 4 = 14 m
As the actual length is 7 m, a 28 mm (D2) copper pipe will be satisfactory.
3 mm Min
D1
D2 Type 'A' Air
Gap
End of pipe
clearly visible
Tundish installation
5 mm
max
Metal Discharge
to Tundish (D1)
Tundish
Heat Resistant
discharge pipe
with continuous fall
3 mm Min

Zeus Maior 24 Instructions
An annual maintenance of the boiler and heating system is recommended. This ensures that the optimal
safety, performance and operation characteristics of the boiler remain unchanged over time.
Warnings
Never expose the wall-mounted boiler to direct vapours from a cooking surface. Use of the boiler by un-
skilled persons or children is strictly prohibited.
Never touch the flue extraction terminal (if fitted) due to the risk of burning caused by high temperatures;
For safety purposes, check that the concentric air intake/flue exhaust terminal (if fitted), is not blocked. If
temporary shutdown of the boiler is required, proceed as follows:
a) drain the heating system if anti-freeze is not used;
b) shut off all electrical, water and gas supplies.
When building or renovation work is carried out in the vicinity of the flue outlet, switch off the boiler and on
completion of work ensure that a qualified technician checks the safety of the installation. Never clean the
appliance or connected parts with flammable substances. Never leave containers or flammable substances
in the same environment as the appliance.
Electrical Safet
- never touch the appliance with wet hands or other parts of the body and never touch when barefoot.
- never pull electrical cables or leave the appliance exposed to atmospheric agents (rain, sunlight, etc.);
- the appliance power supply cable must never be replaced by the user;
- in the event of damage to the cable, switch off the appliance and contact a qualified service technician.
- in the event of prolonged periods when the boiler is not in use, turn off the main power switch.
Operation and Maintenance Instructions
Using the Boiler
Before lighting, make sure that the system is full of water and that the manometer (8) indicates a pressure
of 1 - 1.2 bar.
-Open the gas valve on the gas supply to the boiler.
-Turn main switch (5) to Hot Water or Hot Water/Heating.
N.B.: Once the main switch (5) is turned to the central Heating temperature setting (1) is not active,
and the domestic water temperature is controlled by selector (2). With the switch set to the central
heating temperature is set using selector (1) while selector (2) is used for the domestic hot water. Turn the
selectors clockwise to raise the temperature, anticlockwise to lower it. Boiler operation is now automatic.
Faults
Overheat lockout - Red indicator lamp (3)on. If during operation a fault causes the temperature to exceed
1 °C.the boiler enters this condition. Turn the main switch (5) temporarily to the Reset position. If this con-
dition occurs repeatedly, contact a qualified technician for assistance.
Flue lockage - Red indicator lamp (3) on. If there is a problem with the boiler flue then the boiler enters
‘flue blockage’ mode. Turn the main switch (5) temporarily to the Reset position. If this condition occurs
repeatedly, contact a qualified technician for assistance.
Ignition lockout - Red indicator lamp (6) on. Each time heating or hot water production is required the
boiler lights automatically. If the boiler does not light within 1 seconds, the boiler goes to “ignition lock-
out” (indicator lamp 6 on). Turn the main switch (5) temporarily to the Reset position. This condition may
occur repeatedly if the gas supply is interrupted or if the boiler has been out of service for some time. If this
condition occurs repeatedly, contact a qualified technician for assistance.
Boiler shutdown. Turn off the main switch (5) by turning it to “ ” (yellow indicator lamp 4 off) and close the
gas supply valve upstream of the appliance. Never leave the boiler switched on if left unused for prolonged
periods.
1 Heating Temp Selector
2 Domestic Hot Water Selector
3 Boiler over temperature and flue
block red indicator
4 Power on green indicator lamp
5 -Domestic—Domestic and Heat-
ing– Reset switch
6 Ignition lockout red indicator lamp
7 Boiler Thermometer
8 Boiler Manometer

Zeus Maior 24 Instructions
Lack of water n bo ler.
Periodically check the system water pressure. Make sure that the pressure in the system is between 1
and 1.2 bar. N.B. Close the filling valve on completion. If pressure valves reach around 3 bar the safety
valve may be activated. In this case contact a service technician for assistance. In the event of frequent
pressure drops, contact your plumber to eliminate system leakage.
System flow NTC sensor fault.
If a problem is detected with the system delivery NTC sensor, the boiler will not start; call a qualified techni-
cian.
Domest c c rcu t NTC sensor fault.
If the unit detects an problem in the domestic circuit NTC sensor, the boiler will not produce domestic hot
water; call a qualified technician.
No water c rculat ng.
This occurs if there is overheating in the boiler due to insufficient water circulation through the boiler - check
that shutoff valves are not closed and that the system is free of air . Check that the circulating pump is run-
ning freely. If necessary, remove the pump cover screw and manually rotate the pump impellor using a flat
bladed screwdriver. If lockout occurs repeatedly, contact a qualified technician for assistance.
Dra n ng the system.
To drain the boiler, use the special drain cock. Before draining, ensure that the filling valve is not con-
nected.
Dra n ng the DHW tank.
To drain the tank, use the special drain cock. N.B.: Before carrying out this operation, close the tank cold
water inlet cock and open any domestic circuit hot water cock to allow air to enter the tank.
Ant -freeze protect on.
The boiler comes standard with an anti-freeze function that starts the pump and burner when the water tem-
perature inside the boiler falls below 4°C and stops on exceeding 42°C. The anti-freeze function is opera-
tional if the boiler is in normal mode and not in “lockout” status, and is electrically connected with the main
switch is set to Summer or Winter. To avoid continued operation in the event of prolonged absence, the
system should be drained completely or anti-freeze should be added to the heating system water. In both
cases the boiler domestic water circuit must be drained. In appliances subject to frequent draining, the sys-
tem must be refilled with suitably treated water. Do not use hard water to fill the system or there will be
scale formation in the boiler.
Cas ng Clean ng:
Use damp cloths and neutral
detergent to clean the oiler casing. Never use a rasive or powder
detergents.
Maintenance Operations

Zeus Maior 24 Instructions
The following checks and maintenance should be performed at least once a year.
- Clean the flue side of the heat exchanger.
- Clean the main burner.
- Make a visual inspection of the flue extraction hood for wear or corrosion.
- Ensure correct ignition and operation.
- Ensure correct settings of the burner in domestic water and heating modes.
- Verify correct operation and adjustment of the boiler, in particular:
- operation of the electrical main switch on the boiler;
- operation of the system control thermostat;
- operation of the domestic water control thermostat.
- Ensure gas soundness of the gas intake circuit; insert a “U” or digital type pressure gauge in the pressure
test point upstream of the gas valve and then close the boiler shutoff valve. No pressure variation must
occur in the next five minutes on the gauge.
- Ensure activation of the device for protection against the ionisation flame control gas; activation time must
be less than ten seconds
- Visually inspect to check for leakage of water or oxidation of fittings.
- Check visually that the water safety valve outlets are not blocked and that the tundish is clear.
- Check that the charge of the expansion vessel after discharging system pressure to the zero setting
(check via boiler pressure gauge), is at 1, bar.
- Check that the system static pressure (in cold conditions and after system recharging via the filling valve )
is between 1 and 1.2 bar.
- Check visually that the safety and control devices have not been tampered with and/or shorted, in particu-
lar:
- temperature safety thermostat;
- air pressure switch.
- Check the integrity of boiler Magnesium Anode.
- Ensure correct maintenance and condition of the electrical installation with particular reference to:
electrical cables must be correctly routed
no traces of black marking or burns
Annual maintenance procedures

Zeus Maior 24 Instructions
Zeus Ma or 24 Ser es Var able Heat Output
Zeus Ma or 24 W r ng D agram