Unical AIREX 2S Series Datasheet

AIREX 2S
INSTALLATION AND
SERVICING MANUAL
00333938 - 1st edition - 05/17

2
General Information
CONTENTS
1 GENERAL INFORMATION ................................................................................................................................................................................. 3
1.1 Symbols used in this manual ........................................................................................................................................................................ 3
1.2 Correct use of the appliance......................................................................................................................................................................... 3
1.3 Water treatment ............................................................................................................................................................................................ 3
1.4 Information to be passed to the user ............................................................................................................................................................ 3
1.5 Safety warnings ............................................................................................................................................................................................ 4
1.6 Data badge ................................................................................................................................................................................................... 4
1.7 General information ...................................................................................................................................................................................... 5
1.8 The Clean Air Act 1993 and Smoke Control Areas ...................................................................................................................................... 5
2 TECHNICAL FEATURES AND DIMENSIONS ...................................................................................................................................................6
2.1 Technical features ........................................................................................................................................................................................ 6
2.2 Dimensions and hydraulic connections......................................................................................................................................................... 6
2.3 Main components ......................................................................................................................................................................................... 8
2.4 General Information: ..................................................................................................................................................................................... 8
Reversed flame combustion ......................................................................................................................................................................... 8
Airex boiler structure..................................................................................................................................................................................... 9
3 INSTALLATION INSTRUCTIONS ..................................................................................................................................................................... 11
3.1 General warnings ......................................................................................................................................................................................11
3.2 Installation Codes of Practice....................................................................................................................................................................12
3.3 Packaging .................................................................................................................................................................................................13
3.4 Transportation............................................................................................................................................................................................ 13
3.5 Installation ................................................................................................................................................................................................. 14
3.6 Boiler system connection...........................................................................................................................................................................14
3.7 Connection to safety heat excanger drain ................................................................................................................................................. 15
3.8 Recirculation pump.................................................................................................................................................................................... 15
3.9 Assembly instruction..................................................................................................................................................................................16
3.10 Flue outlet connection................................................................................................................................................................................ 20
3.11 Electrical connections ................................................................................................................................................................................ 21
3.12 Standard panel board ................................................................................................................................................................................ 22
3.13 Hydraulic and electrical connection diagrams ........................................................................................................................................... 24
3.14 Filling the system....................................................................................................................................................................................... 26
4 BOILER START-UP........................................................................................................................................................................................... 27
4.1 Initial lighting............................................................................................................................................................................................. 27
4.2 Fire wood................................................................................................................................................................................................... 28
4.3 Wood moisture ..........................................................................................................................................................................................28
4.4 Fire wood dimensions................................................................................................................................................................................28
4.5 Initial lighting checks..................................................................................................................................................................................28
4.6 Start-up...................................................................................................................................................................................................... 29
4.7 Combustion air adjustment........................................................................................................................................................................ 30
4.8 Checks to carry out after the first start .....................................................................................................................................................31
4.9 Warnings ................................................................................................................................................................................................... 31
4.10 Thermostat adjustments............................................................................................................................................................................ 32
4.11 Summer operation.....................................................................................................................................................................................32
4.12 Fault finding for boilers with standard control panel ..................................................................................................................................33
5 SERVICING AND MAINTENANCE SCHEDULE ..............................................................................................................................................34

3
General Information
1.1 - SYMBOLS USED IN THIS MANUAL
When reading this manual particular care has to be given to the parts marked with the followings symbols:
NOTE! Suggestions for the
user
WARNING! Indicates a potentially
dangerous situation for the pro-
duct and the environment
DANGER! Indicates serious
danger for your personal safety
and for your life
1.2 - A CORRECT USE OF THE APPLIANCE
The AIREX 2S appliance has been designed utilizing today’s heating technology and in compliance with
the current safety regulations.
However, following an improper use, dangers could arise for the safety and life of the user or of other people,
or damage could be caused to the appliance or other objects.
The appliance is designed to be used in hot water central heating systems.
Any other use of this appliance will be considered improper.
UNICAL declines any responsibility for any damages or injuries caused by an improper use; in this case
the risk is completely at the user’s responsibility.
In order to use the appliance according to the foreseen scopes it is necessary to carefully follow the in-
structions given in this manual.
1.3 - WATER TREATMENT (refer to specific guide)
• In hard water areas where the main water can exceed 15°f total hardness, a scale reducing device is recommen-
ded. The choice of this device has to be made taking into consideration the characteristics of the water.
1.4 - INFORMATION TO BE HANDED OVER TO THE USER
The user has to instructed on the use and operation of his heating system, in particular:
- Hand over these instructions to the end user of the appliance, together with any other literature, regarding this ap-
pliance, placed inside the envelope contained in the packaging. The user has to keep these documents in a safe
place in order to always have them at hand for future reference.
- Inform the user on the importance of air openings and of the flue outlet system, stressing the fact that it is absolutely
forbidden to make any alterations to the boiler.
- Inform the user how to check the system’s water pressure as well as informing him how to restore the correct pres-
sure.
- Explain the function of temperature controls, thermostats, heating controls and radiators, to ensure the greatest
possible fuel economy.
- If the appliance is sold or transferred to another owner or if the present user moves home and leaves the appliance
installed, ensure yourself that the manual always follows the appliance, so that it can be consulted by the new owner
and/or installer.
1GENERAL INFORMATION
Warning: this manual contains instructions to be used exclusively by the installer and/or a competent person in accor-
dance with the current laws.
The end user is NOT autorized to carry out any service work on the boiler.
Failure to follow the instructions given in this manual, which is supplied with the boiler, could cause injury to persons,
animals or damage to property. UNICAL shall not be held liable for any injury and/or damage.

4
General Information
1.6 - DATA BADGE
The data badge is adhesive and placed inside the documentation envelope; it must be glued on to one side of the casing, on the
external part, by the installer.
The boiler’s serial number is indicated on a small aluminium plate riveted on the boiler’s front plate (front side, upper right hand side).
1.5 - SAFETY WARNINGS
WARNING!
The installation, adjustment, and servicing of this appliance must be carried out by a competent, qualified
person and installed in accordance with the current standards and regulations. Failure to correctly install
this appliance could cause injury to persons, animals or damage to property. The manufacturer shall not
be held liable for any injury and/or damage.
DANGER!
NEVER try to carry out any repairs or service work on the boiler on your own initiative.
Servicing or repairs of the appliance must be carried out by qualified service engineers;
UNICAL recommends drawing up a service contract.
Bad or irregular servicing could compromise the safe operation of the appliance, and could cause injury to persons,
animals or damage to property for which UNICAL shall not be held liable.
Modifications to parts connected to the appliance
Do not carry out any modifications to the following parts:
- the boiler itself
- to the electrical parts
- to the flue pipe, safety relief valve (if fitted)
- to the constructive components which influence the appliance’s safe operation
WARNING!
When tightening or loosening the screw pipe connections, use only adequate fork spanners.
The improper use and/or the use of inadequate equipment can cause damages.
Explosive and easily inflammable substances
Do not use or leave explosive or easily inflammable material (as for example: petrol, paint, paper) in the room where
the appliance has been installed.

5
General Information
1.7 - GENERAL WARNINGS
This instruction manual is an integral and indispensable part of
the product and must be retained by the user.
Please read carefully the instructions contained in this manual, as
they provide important indications regarding the safe installation,
use and servicing of this appliance.
Keep this manual in a safe place for future reference.
The installation and servicing must be carried out in accordance
with the regulations in force, according to the manufacturer’s
instructions, and by legally competent authorized persons.
By a competent person, we imply a person who has a specific
technical qualification in the field of components for central hea-
ting systems for domestic use, domestic hot water production
and servicing.The person must have the qualifications foreseen
by the current laws in force.
Bad or irregular servicing could compromise the safe operation
of the appliance, and could cause injury to persons, animals or
damage to property. The manufacturer shall not be held liable
for any such injury and/or damage.
Before carrying out any cleaning or servicing, turn off the elec-
trical supply to the boiler by means of the ON/OFF switch and/
or by means of the appropriate shutdown devices.
Do not obstruct the air inlet openings.
In the event of failure and/or faulty functioning of the appliance,
switch off the boiler. Do not attempt to make any repairs: contact
qualified technicians.
Any repairs must be carried out by Unical authorized technicians
and using only original spare parts. Non-observance of the above
requirement may jeopardize the safety of the appliance.
To guarantee the efficiency and correct functioning of the ap-
pliance it is indispensable to have the boiler serviced annually
by a qualified person.
If the boiler remains unused for long periods, ensure that any
dangerous parts are rendered innocuous.
If the appliance is sold or transferred to another owner or if the
present user moves home and leaves the appliance installed,
ensure yourself that the manual always follows the appliance
so that it can be consulted by the new owner and/or installer.
Only original accessories must be used for all appliances sup-
plied with optional accessories or kits (including electrical ones).
This appliance must be used only for the purposes for which it has
been expressively designed. Any other use shall be considered
incorrect and therefore dangerous
1.8 - THE CLEAN AIR ACT 1993 AND SMOKE
CONTROL AREAS
Under the Clean Air Act local authorities may declare the
whole or part of the district of the authority to be a smoke
control area. It is an offence to emit smoke from a chimney
of a building, from a furnace or from any fixed boiler if loca-
ted in a designated smoke control area. It is also an offence
to acquire an “unauthorised fuel” for use within a smoke
control area unless it is used in an “exempt” appliance
(“exempted” from the controls which generally apply in the
smoke control area).
In England appliances are exempted by publication on a
list by the Secretary of State in accordance with changes
made to sections 20 and 21 of the Clean Air Act 1993 by
section 15 of the Deregulation Act 2015. Similarly in Scotland
appliances are exempted by publication on a list by Scot-
tish Ministers under section 50 of the Regulatory Reform
(Scotland) Act 2014.
In Wales and Northern Ireland these are authorised by re-
gulations made by Welsh Ministers and by the Department
of the Environment respectively.
Further information on the requirements of the Clean Air
Act can be found here:
https://www.gov.uk/smoke-control-area-rules
Your local authority is responsible for implementing the
Clean Air Act 1993 including designation and supervision
of smoke control areas and you can contact them for details
of Clean Air Act requirements”
“The AIREX 2S 65 & 85 UK units have been recommended
as suitable for use in smoke control areas when fitted with
a buffer tank as specified in Technical Features and Dimen-
sions section when burning wood logs”

6
Technical features and dimensions
A
F
30
BT1
T4
T6
T4
T3
T5
T1
T4
T3
T2-T8
E
1
7
3
4
9
D
C
G
T2
T8
T7
6
5
8 8
H
2.2 - DIMENSIONS
AND HYDRAULIC
CONNECTIONS
fig. 1
1 Panel board
2 Primary air setting
3 Secondary air setting
4 Cleaning openings
5 Rear smoke chamber
6 Loading door
8 Fan (n°2 fan for the model AIREX 65 2S and
AIREX 80 2S)
9 Combustion chamber door with flame sight
glass
10 Primary & Secondary air inlet
T1 Central Heating flow
T2 Central Heating return
T3 Chimney connection
T4 Safety heat exchanger connections
T5 Connections for eventual trap sensor valve
temperature relief
T6 Bulb holder for safety thermal discharge valve
T7 Bulb holder for thermostat and thermometer
T8 Boiler drain
2.1 - TECHNICAL FEATURES
The Airex is a steel boiler running by natural wood in logs,
total gasification, flame inverted, with the combustion chamber
under negative pressure.
It comes in the following models:
AIREX 25 2S
AIREX 40 2S
AIREX 50 2S
AIREX 65 2S
AIREX 80 2S
The boiler AIREX is complete with all the safety and control
devices required by the relevant standards.
COMPONENTS DESCRIPTION :
• Steel boiler with combustion chamber partially covered with
refractory
• Burner in refractory material
• Horizontal smoke channels
• Front door, for wood loading, insulated with refractory con-
crete
• Intermediate door complete with combustion air adjust-
ments
2TECHNICAL FEATURES
AND DIMENSIONS
• Lower door, insulated with refractory conctrete and equipped
with flame sight glass
• Rear smoke chamber with side openings for inspection and
ashes removal
• Smoke evacuation via a sucking fan (n° 2 fan for the model
AIREX 65 2S and AIREX 80 2S)
• Patented thermostatic valve system
• Safety heat exchanger
• Boiler body insulated with mineral wool panels with thick-
ness of 60 mm
• Steel casing powder painted
• Recirculation pump kit (optional)
PANEL BOARD:
• Main switch with signal lamp
• Fan switch
• C.H. pump switch
• General fuse
• Working thermostat
• Safety thermostat
• Boiler thermometer

7
Technical features and dimensions
AIREX 25 2S AIREX 40 2S AIREX 50 2S
(kW) 29 47 58
A
B
C
D
E
F
G
560
700
655
700
655
900
1225 1355
190
160
190
160
245
1030
1355
190
160
245245
1140 1140
(mm)
(mm)
(mm)
(mm)
(mm)
(mm)
(mm)
AIREX 65 2S
65
755
955
1405
190
160
245
1180
AIREX 80 2S
80
755
1255
1405
190
160
245
1180
* Power achieved with good quality wood containing 15% humidity
** Pressure drop for a flow rate corresponding to a Delta T of 15K.
T3
T4
T5 - T6 - T7 - T8
UNI ISO 7/1
(Ø mm)
UNI ISO 7/1
Rp 1¼
150
R ½
Rp ½
Rp 1½
200
R ½
Rp ½
Rp 1½
200
R ½
Rp ½
(m c.a.)
(l) 90
0,10
110
0,08
140
0,12
0,60,40,3
(mm c.a.)
(bar)
(l)
(mm)
(kg)
3
95
290x340
396
3
135
350x440
485
3
185
350x440
603
(cm) 50 50 70
Rp 2
220
R ¾
Rp ½
170
0,06
0,3
3
235
340x520
760
70
Rp 2
220
R ¾
Rp ½
220
0,10
0,5
3
325
340x520
927
100
UNI ISO 7/1
H315 315 315
(mm) 315 315
MODELS
MNOMINAL OUTPUT *
DIMENSIONS:
CONNECTIONS T1 - T2
BOILER WATER CONTENT
WATER SIDE PRESSURE DROP **
SMOKE SIDE PRESSURE DROP
MAX. WORKING PRESSURE
FIRE BOX STORAGE VOLUME
FIRE BOX DIMENSIONS
WEIGHT
WOOD LOGS LENGTH
4000
4150
4300
4450
4600
4750
4900
5050
5200
5350
5500
5650
5800
5950
0510 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85
Volume of buffer (liters)
Central heating dissipation ( kW )system
Sizing of buffer for AIREX 80 2S
2500
2650
2800
2950
3100
3250
3400
3550
3700
3850
Sizing of buffer for AIREX 65 2S
Sizing of buffer
RECOMMENDED BUFFER SIZE (l) See diagram below
- - -

8
Technical features and dimensions
3
8
11
12 1413
17
12
15
18
M
R
9
10
16
4
6
5
F
F
7
2.3 - MAIN COMPONENTS
1. Panel board
2. Casin top panel
3 N°2 side panels
4. Anti-smoke door fitted on hinges
5. Wood storage door with refractory insulation
and sealing rope.
6. Central door with sealing gasket &locking
screws for primary and secondary air
7. Fan ( n°2 fan for the models AIREX 65 2S and
AIREX 80 2S)
8. Combustion chamber door with sealing gasket,
refractory insulat. & flame sight glass
9. Combustion chamber in thick steel
10. Heat exchange fin
11. Boiler drain
12. Thermal discharge safety heat exchanger
13. Smoke by-pass with rod
14. Boiler body insulation in mineral wool
15. Boiler body
16. Refractory burner with fire bars and grate
17. Smoke chamber
18. Thermostatic valve
M C.H. flow
R C.H. return
fig. 2
N.B.:
The fire bars and the refractory steel grate are subject to wear; it is therefore advisable
to carry out an annual inspection to prevent bad boiler operation.
2.4 - GENERAL INFORMATION:
REVERSED FLAME COMBUSTION
Every body knows that to make a match lasting it must be held
with its head upwards.
This is because it is necessary that the flame, in its convective
motion, does not meet another fuel in addition to the one which
has generated it. As in residential heating the fuel is in form of
wood logs which are loaded from the top, the flame has to go in
the opposite way, i.e. downwards.
Natural draught is a very variable source of depression, accor-
ding to the type of chimney, on the weather conditions, on the
type of fuel, etc.
Therefore it is necessary to integrate it with forced ventilation
in order to stabilize it.
By fitting a fan it is possible to considerably reduce the section
of the gas passages on the grate and furthermore there are no
problems with cold starts.
The small grate permits a more controlled passage of combustion
air, contrarily to what happens with the large traditional grates.
The air can be perfectly dosed because the grate, covered with
fired wood, has the same crossing resistance and thus the
combustion will be always optimal.
Unical has already used this principal for many years with the
GASOGEN G3 2S boiler.
The AIREX 2S boiler today has reached such a high level of
perfection that it can pass all the most stringent tests foreseen
by the European Standards in force concerning the environment.

9
Technical features and dimensions
fig. 3
AIREX BOILER STRUCTURE
The hydraulic system inside the boiler is designed in such a
way that a thermostatic system keeps always the water tem-
perature high that surrounds the wood storage room so as to
eliminate the dangerous phenomenon of condensation.
The boiler is composed of two oval elements placed inside
each other, so that between the two a cavity of water (Fig. 3)
is formed.
We can distinguish the following parts (fig.3):
1. Fire wood storage and drying area
2. Gasification zone
3. Embers zone
4. Refractory burner
5. Combustion chamber
6. Heat exchange surface
7. Refractory steel cradle
8. Boiler water
9. Thermostatic system
10. Safety heat exchanger
M C.H. system flow
R C.H. system return
fig. 4
A
A
M
R8
7
9
10
1
2
3
4
5
6
GASIFICATION ZONE (2)
The gasification takes place in the lower part of the firewood
storage.
It is very important that the gasification is as regular as possible,
so as not to overload the burner with gas.The gasification speed
depends on the quantity of the wood and the dimensions of the
drying area. Generally, it is better to use large logs if they are
dry and small logs if the wood is wet . The quantity of primary
air, proportional to the delivered output, is regulated via the
adjustment system.
EXCHANGE SURFACE (6)
As the boiler operates on wood, and because the sulphur con-
centrations are not very high , it is important to obtain very low
smoke temperatures in order to increase the water efficiency.
To obtain this Unical has opted for an exchange surface with
dry smoke passes (fig. 4), which have already been extensively
tested in oil fired boilers working at low water temperature, thus
permitting low smoke temperatures without danger of conden-
sate forming.
The surfaces of the dry passages “A” (fig. 4) have had incisions
made on them in order to avoid dilatation problems.
The solid residues of combustion (ashes), which lie on the high
temperature refractory-lined cradle (fig. 3, pos. 7,) will become,
with the time, always lighter until they will be dragged by the
gas speed and will be deposited in the lowest area of the rear
smoke chamber, from which they will be removed during the
cleaning operation.
REFRACTORY BURNER (4)
The burner is made up of refractory stone (fig. 3, pos. 4).
This stone has an oval central opening through which the flame
passes.
The embers lie directly on the main stone which divides the fire
wood storage from the lower combustion chamber.
Furthermore the main refractory stone has a rectangular seat in
which the opportunely grooved cast iron fire bars are placed (fig.
5, pos. 2), which receive the secondary air from a front distributor.

10
Technical features and dimensions
S S S
M
F
F
R
P
F
P
P
S
P-S
F
1
2
fig. 5
fig. 6
fig. 7
1
2
3
T1
1. Metallic grate
2. Cast iron fire bars
M = C.H. flow
R = C.H. return
P = Primary air
S = Secondary air
F = Flue
The embers are prevented from falling by cylindrical pieces of
refractory steel. The combustion gases, poor in oxygen and still
rich in carbon not yet combined, travel across the embers and
enter the opening in the centre of the main stone.
Inside this pre-combustion chamber, the gases combine with
the pre-heated secondary air coming through the grooves of
the two cast iron fire bars.
The resulting flame will be highly oxygenated and have a light
blue colour. This flame comes out from the oval opening and
invades the combustion chamber.
Due to the high temperatures the refractory burner will become
a bright red colour.
COMBUSTION CHAMBER (5)
The combustion is optimised by increasing the flame tempera-
ture and producing a strong turbulence in the bottom chamber.
For this reason the flame, in addition to not to touching cold walls
irrigated by the water, rebounds and is divided on a semicircular
cradle which rests on the lower exchange surfaces (baffles),
which, as well delimiting the smoke passages, also has the task
of collecting the ashes and possible embers.
The flames, after having bounced off the walls of the bottom area
and the refractory ones, direct themselves with a whirling motion
towards the front part of the combustion chamber and enter the
flue ducts. The combustion will be complete and clean and the
dominant colour will be that of the ashes: white.
THERMOSTATIC VALVE (9)
As well known, wood normally has a high moisture content when
compared with other types of fuels. The first operation which
occurs inside the fire wood storage is therefore the drying phase.
The high moisture content can then cause condensation phe-
nomena within the boiler and also in the chimney.
To limit the inconvenience in the boiler it is necessary to maintain
high working temperatures.
For this reason the boiler is equipped with a patented thermo-
static system (fig. 6) which permits the boiler temperature to be
kept constantly high and in particular, in the fire wood storage,
where the condensation phenomena is more likely to occur.
In order to reduce the consequences of condensate formation
(formation of layers of tar, corrosion, etc.) it is advantageous to
dimension, time by time, the wood load to the actual needs, so
as to prevent long stop overs with the wood storage completely
full of humid wood.
Nevertheless all these expedients do not impede the formation of
condensate in the chimney.Therefore we suggest, when building
the chimney, to use air-tight components, to avoid the
condensate damaging the building structure.

11
Instructions for the installer
3INSTALLATION
INSTRUCTIONS
3.1 - GENERAL WARNINGS
WARNING!
This boiler is to be destined only to the use
for which it has expressly been designed for.
Every other use is to be considered improper
and therefore dangerous.
This boiler is designed to heat water at a
temperature inferior to boiling point at an
atmospheric pressure.
WARNING!
These appliances are exclusively designed
for indoor installations or installed in adequa-
te sitings. Therefore these appliances must
not be installed and operated outdoors. An
outdoor installation could cause malfunctio-
ning and could be dangerous.
Before installing the boiler the following points
have to be carried out by a professionally
qualified person:
a) The whole system should be thoroughly
flushed in order to remove any residual dirt or
grime which could compromise correct boiler
operation.
b) Check that the chimney/flue pipe has an ade-
quate draught, does not have any constrictions,
and that no other appliance’s flue outlets have
been fitted, unless the chimney is serving more
than one heating appliance, according to the
specific standards and regulations in force. The
connection between the boiler and chimney/flue
outlet can be made only after this verification has
been carried out.
WARNING!
The appliance must be installed by a qualified,
registered engineer, whom, under his own
responsibility, guarantees the compliance
of the standards according to the latest re-
gulations.
NOTE:
The boiler must be connected to a heating system
which is compatible to its performance and output.

12
Instructions for the installer
3.2 - INSTALLATION CODES OF PRACTICE
The AIREX 2S is a boiler foreseen for operation with firewood.
The appliance must be installed in compliance with all local
applicable laws and regulations.

13
Instructions for the installer
3.3 - PACKAGING
The AIREX 2S is supplied dismantled: the casing, the fan, the
control panel, the handles and the cleaning accessories are
delivered separately in carton boxes
(fig. 8).
After having unpacked everything, make sure that
the consignment is intact and undamaged.
In case of doubt do not to use the appliance and
inform the supplier.
Keep the packaging material (cardboard box,
plastic bags, polyester protection etc.) out of
the reach of children since they can be
dangerous.
UNICAL refuses all liability for injury to persons,
animals or damage to property deriving from not
having respected the above mentioned recom-
mendations.
Packages description:
1. Boiler body
2. Package containing the casing and boiler insulation
3. Package containing the panel board
4. Package containing the smoke extraction fan
5. Package containing: air inlet manifold , smoke chamber cleaning doors,
handles, flame control mirror , screws and nuts, cleaning accessories. This
package is shipped inside the fire wood storage room
In the documents, placed in the fire wood storage room, you
will find:
- User’s instruction manual
- Installation and servicing instruction manual
- Guarantee card
- Adhesive data plate
- Adhesive label with ventilation requirements
If the boiler will not be used for a long period,
it should be adequately protected.
fig. 8
3.4 - TRANSPORTATION
To facilitate the transport, the loading and unloading of the boiler,
on the upper part of the boiler body there are suitable hooks
(fig. 8) for lifting.
1
23
G
4
5

14
Instructions for the installer
600
1000
1300 600
600
fig. 9
3.5 - INSTALLATION
The boiler does not differ from a normal solid fuel fired boiler;
therefore there are no particular installation codes of practice
other than the applicable national and local safety regulations
and laws.
The installation room must be properly ventilated via
openings, which should have a total surface of
at least 0,5 m².
To facilitate cleaning of the flue circuit, a free
space, not inferior to the length of the boiler,
must be left in front of the boiler.
In addition ensure that the doors can open 90°
without meeting any obstacles.
The boiler can be placed directly on the
floor, because it is equipped with a
self-supporting frame.
Nevertheless, in case of installation in very
damp boiler rooms, it is preferable to fit a
concrete support.
When installation is completed, the boiler
should be in a horizontal position and stable so
as to reduce possible vibrations and noise.
An adequate clearing must be left behind the
boiler for servicing.
INSTALLATION IN BOILER ROOM
Note:
The minimum clearances indicated in figure 9 are compulsory
only for boilers with an output higher than 35 kW (Italian re-
quirement)
3.6 - BOILER SYSTEM CONNECTION
Warning!
Make sure the connection of the pipelines is
free of mechanical stresses, in order to avoid
water losses!
The C.H. flow and return must be connected to the respective
connections in the boiler, as indicated on page 7.
When determining the size of the CH circuit pipes it is essential to
bear in mind the pressure losses induced by any of the system’s
components and by the configuration of the same system.
The piping route has to be designed taking all the necessary
precautions in order to avoid air locks and to facilitate the con-
tinuous purging of the system.
Ensure yourself that the system’s piping is not
used as earth clamps for the electrical or tele-
phone system.They are absolutely unsuitable for
this use. In a short time this could cause serious
damage to the piping, boiler and radiators.

15
Instructions for the installer
SCARICO
1
2
ALIMENTAZIONE
fig. 10
3.7 - CONNECTION TO SAFETY HEAT
EXCHANGER DRAIN
Solid fuel fired boilers have to be installed
with the safety devices foreseen by applicable
regulation and laws.
For this purpose the AIREX 2S boilers are
fitted with a safety heat exchanger.
On this safety heat exchanger the installer must fit a heat
discharge valve, whose control bulb has to be inserted in the
bulb holder placed onto the rear wall of the wood fired boiler.
The inlet and outlet connections can be inverted.
However we recommend that the valve be fitted on the cold
water inlet.
In correspondence of the safety heat exchanger outlet, we re-
commend fitting a drainage pipe with a funnel and siphon that
lead to an adequate drainage. The drainage has to be visible.
Warning!
In absence of this precautionary measure,
the eventual intervention of the heat dischar-
ge valve could cause damages to people,
animals or property. The manufacturer shall
not be held liable for any such injury and/or
damage.
MAINS
DRAIN
3.8 - RECIRCULATION PUMP
For correct boiler operation it is necessary to install a re-
circulation pump in the boiler.
The recirculation pump, supplied as an optional kit in two
different versions, basic or for buffer storage tank control,
will have to be connected as shown in figs. 19 and 20.
If the recirculation pump is not installed, besides limiting
the boiler’s life span, it will invalidate the warranty.
WARNING!
The hardness of the mains water supply
conditions the boiler’s life span.
Depending on the hardness of the of the
mains water supply the possibility of instal-
ling a water
softener has to be taken into consideration.
In hard water areas where the main water can
exceed 15°f total hardness, water treatment is
always recommended.

16
Instructions for the installer
3.9 - ASSEMBLY
INSTRUCTIONS
Fan assembly
Fit the fan to the smoke chamber.
(n° 2 fan for models AIREX 65 2S
and AIREX 80 2S).
Insulation and casing as-
sembly
- Detail “A”: Fit the knob 4 on the
upper door closing handle . Fit, in
the sequence, the screw, the nut and
the knob (pos. 1, 2, 3) on the upper
R.H. side corner and tighten nut and
knob .
- Detail “B”: install the air collector (n°
2 collectors for the model AIREX 65
2S and AIREX 80 2S) . Ascertain
that the internal non-return plate is
free to move, by acting manually on
the extenal lever of the air manifold.
The draft adjustment on the primary
and secondary air is described on
pages 29 and 30.
- Detail “C” Fit, in the sequence, the
screw, the nut and the knob (pos. 1,
2, 3) on the lower R.H. side corner
of the lower door and tighten nut and
knob .
- Detail “D” Fit on the boiler basement
the supporting feet
- Detail “E” Fit the inspection door on
the smoke chamber
- Hang the mirror (pos.5) on the flame
sight glass of the lower door.
fig. 11
fig. 12
fig. 13
IMPORTANT:
When installing the fan it is necessary to
check the tightness of the seal on the
smoke chamber, otherwise it would
cause the deformation of the wall
resulting in severe damage to the impeller
and / or fan motor.
This inconvenience is much more rapid
as more frequent is the opening of the
wood loading door.
1
2
3
4
Fit the boiler body insulation and make a suitable cut near
the upper C.H. flow connection.
- Wrap on the mineral wool insulation the plastic strap
and insert one of its ends in the locking slot as shown
in the detail1.
- Holding the end of the strap already inserted, proceed
with the other end by folding inward the plastic pin as
shown in detail 2.
- Pull the two ends of the strap (as shown in details 3
and 4) until the strap adhere to all the mineral wool
covering the boiler body. It is recommended not to over
stretch the strap; an excessive crushing of mineral
wool, would cause a not homogeneous insulation.
In case of maintenance it is possible to remove the
strap by acting on the locking slots.
FIG. 13
1
2
3
4
1
32
C
E
A
D
B
5

17
Instructions for the installer
2
1
3
7
54
6
fig. 14
Fit the microswitch onto its support and adjust the pushing
washer axially in order to allow the microswitch to be regularly
operated when the upper loading door is closed.
Ascertain that the by-pass disk is perfectly closed when the door
is closed and the boiler in operation.
It is possible to ascertain this by simulating the closing of the
upper door and observing, from the inside of the wood storage
room, if, with a lamp placed in the chimney connection, there
is no visible light.
If necessary, adjust the length of the by-pass rod, acting on the
front threaded shaft.
Otherwise, adjust the length of the by-pass rod by acting on
the threaded bar front.
- Hook the casing L.H. side panel to the boiler body (pos. 1)
- Hook the casing L.H. side panel to the boiler body (pos. 2)
- Place on the ground the casing upper panel and fit on it the
panel board (pos. 3, 4, 5, e 6).
- Fix to the top panel the rear profile (pos. 7)supporting the
cable clamps .
- Open the panel board by acting with a screwdriver on the
two side screws.
- Rotate forward the panel board cover.
Insert all the capillaries of the thermostats and thermome-
ter (unroll them carefully), the outgoing fan(s) connecting
cable(s), the incoming microswitch cable controlling the
loading door opening and the outgoing electrical supply cable
through the two rectangular holes on the base of the panel
board.
- Place the casing upper panel on the boiler addressing the
ends of the capillaries toward the rear of the boiler.
- Stick the boiler technical data badge to the most accessib-
le side panel after having cleaned and degreased with a
suitable solvent the affected area.
Remove the protecting film from the data badge and apply by
sticking perfectly
Do not remove the label from the boiler because it would
affect the adhesion.
fig. 15

18
Instructions for the installer
fig. 16
The thermostats bulbs can be identified by labels stickers
fixed on the respective capillary. Therefore, during any mainte-
nance, pay attention that the labels will not be removed.
A) Place the bulb of the working thermostat (Te), of the Max
thermostat, (Tmax), of the Min. Thermostat (Tsc) and of
the thermometer in the central bulb holder
B) Place the bulb of the safety thermostat (Ts) in the R.H. side
bulb holder
C) Fix the bracket (pos. 1), supporting the fan socket to
casing L.H. side panel, using the 3 screws, supplied with
the product, and tighten the screw (pos. 2) on the smoke
chamber.
Fit on the bracket the fan socket (pos. 3).D) Con-
nect the fan plug to the socket (pos. 3)
E) Make the electrical connections of the supply line, the
pump(s) and other possible devices according to the wiring
diagrams shown in chapters 3.12 and 3.13.
Close the panel board.
Pay attention that the cables do not come in contact with
the smoke chamber. During operation, this reaches high
temperatures.
TERMOSTATO
DI ESERCIZIO (Te)
TERMOMETRO
MOLLA
DI CONTATTO
TERMOSTATO
DI MINIMA (Tsc)
MOLLA DI
FISSAGGIO
TERMOSTATO
DI MASSIMA (Tmax)
TERMOSTATO
DI SICUREZZA (Ts)
MOLLA DI
FISSAGGIO
3
21
The solid fuel boilers must be installed with all the securi-
ty devices foreseen by the laws in force.
For this purpose, AIREX boilers are equipped with a built-
in safety heat exchanger.
A) Connect the safety discharge valve (pos. 1) and insert its
temperature sensor into the bulb holder (pos.2)
The safety discharge valve may be mounted either on the
right or on the left.
It is recommended to convey the discharge of the safety
heat exchanger.
Remember that for the solid fuel boiler, due to the thermal
inertia of the fuel, the installation of the termal discharge
valve is required.
SCARICO
1
2
ALIMENTAZIONE
fig. 17
WORKING THERMOSTAT (Te)
THERMOMETER
MINIMUM THERMOSTAT (Tsc)
FIXING CLIP
CONTACT SPRING
HIGH LIMIT THERMOSTAT (Tmax)
FIXING CLIP
SAFETY THERMOSTAT (Ts)
MAINS
DRAIN

19
Instructions for the installer
1
4
5
6
2
3
7
8
10
11
12
13
14
15
9
For the correct operation of the AIREX range of boilers it is
necessary to foreseen a recirculation pump, to prevent a low
temperature return, which could compromise the life of the
boiler.
UNICAL, to help its customers, has therefore developed a
hydraulic kit for recirculation that enhances the function of the
circulating water in the boiler.
This kit is supplied as an option and is available by indicating
the model of your boiler.
fig. 18

20
Instructions for the installer
5
5
1
2
3
4
6
7
8
6
7
8
3.10 - FLUE OUTLET CONNECTION
The flue system must be installed in accordance with the local
regulation and national codes of practice.
The chimney is of fundamental importance for the correct boiler
operation: it is therefore necessary that the chimney is imper-
meable and properly insulated.
Old or new chimneys, built without respecting the specific
requirements can be recovered by “tubing” the chimney itself.
It will be necessary to introduce a metallic pipe inside the existing
chimney and insulate the space between the metallic pipe and
the chimney.
Chimneys made of prefabricated blocks must have perfectly
sealed joints to avoid that flue condensate smudge the walls
due to permeation.
The entrance to the chimney should be with an angle of 45°.
At the base of the chimney a flue inspection opening has to be
made.
It is advisable to insulate the flue pipe connecting the boiler to
the chimney in order to reduce the heat losses and noise.
1. Boiler
2. Flue outlet connection
3. Ashes collecting chamber
4. Chimney
5. External flue lining
6. Prefabricated blocks
7. Insulation
8. Flue outlet
We recommend using only flue pipes suitable
to the type of fuel used.
Damages caused by installation errors and for
non-observance of the instructions given by
the same manufacturer will invalidate all the
supplier’s contractual or extra contractual
responsibilities.
The flue outlet has to meet the latest regulations in force.
fig. 19