Unical XC-K3 Series User manual

XC-K3
1000 1250 1500 1750
2000 2500 3000
ENGLISH
INSTALLATION AND MAINTENANCE INSTRUCTIONS

2
https://www.unicalag.it/prodotti/professionale-300/commercial-condensazione-inox/341/xc-k 3
Provisions for proper disposal of the product
After decommissioning, this appliance must not be disposed of as mixed urban waste.
Separate waste collection is mandatory for this type of waste, in order to allow the recovery and reuse of the
materials making up the appliance.
Please contact operators authorised for the disposal of this type of appliances
Incorrect management of waste and of its disposal has potential negative e󰀨ects on the environment and human health
The symbol on the appliance, represents the prohibition to dispose of the product as mixed urban waste.

3
Technical features and dimensions Technical Features General information
Maintenance instructions
ENGLISH
TABLE OF CONTENTS
1 GENERAL INFORMATION................................................................................................................................................................................ 4
1.1 Symbols used in the manual......................................................................................................................................................................... 4
1.2 Appropriate use of appliance........................................................................................................................................................................ 4
1.3 Water treatment ............................................................................................................................................................................................ 4
1.4 Information for user or system manager....................................................................................................................................................... 4
1.5 Safety warnings ............................................................................................................................................................................................ 5
1.6 Technical data plate ...................................................................................................................................................................................... 6
1.7 General warnings.......................................................................................................................................................................................... 7
2 TECHNICAL FEATURES AND DIMENSIONS................................................................................................................................................. 8
2.1 Technical features......................................................................................................................................................................................... 8
2.2 Main components ......................................................................................................................................................................................... 8
2.3 Dimensions ................................................................................................................................................................................................. 10
2.4 Operating data ............................................................................................................................................................................................ 16
3 INSTALLATION INSTRUCTIONS................................................................................................................................................................... 15
3.1 General warnings ...................................................................................................................................................................................... 15
3.2 Installation standards ................................................................................................................................................................................ 16
3.3 Packaging.................................................................................................................................................................................................. 16
3.3.1 Handling ........................................................................................................................................................................................... 16
3.4 Positioning in boiler room .......................................................................................................................................................................... 17
3.5 Burner........................................................................................................................................................................................................ 18
3.5.1 Choosing the burner........................................................................................................................................................................ 18
3.5.2 Installing the burner......................................................................................................................................................................... 18
3.5.3 Connecting ame sight glass to burner ........................................................................................................................................... 19
3.6 Furnace door adjustment, opening and closing ........................................................................................................................................ 19
3.6.1 Boiler XC-K 3.................................................................................................................................................................................... 19
3.7 Connecting ue exhaust pipe .................................................................................................................................................................... 20
3.8 Connecting boiler to system ...................................................................................................................................................................... 20
3.9 Condensation drainage ............................................................................................................................................................................. 21
3.10 Filling the system ....................................................................................................................................................................................... 22
3.11 Assembling casing ..................................................................................................................................................................................... 23
3.11.1 Probe connection............................................................................................................................................................................ 24
3.12 Electrical connectionsi ............................................................................................................................................................................... 25
3.13 MODULATING MASTER (dual stage master) panel board ....................................................................................................................... 26
3.13.1 Programming heating controllers with single boiler........................................................................................................................ 27
3.13.2 Programming parameters Lago basic ............................................................................................................................................ 29
3.13.3 Hydraulic and electric system connection with panel board .......................................................................................................... 30
3.13.4 Programmazione dei termoregolatori con caldaie in cascata......................................................................................................... 31
3.14 MODULATING CASCADE (dual stage cascade) panel board .................................................................................................................. 32
3.14.1 Hydraulic and electric system connection with boilers in cascade ................................................................................................ 33
3.15 Commissioning.......................................................................................................................................................................................... 35
3.16 Adjusting the burner .................................................................................................................................................................................. 36
4 INSPECTIONS AND MAINTENANCE............................................................................................................................................................ 36
Inspection and maintenance instructions........................................................................................................................................................... 36
Boiler body maintenance ................................................................................................................................................................................... 37
Maintenance of burner....................................................................................................................................................................................... 37
Checking ignition electrode................................................................................................................................................................................ 37
Components to check during yearly inspection ................................................................................................................................................. 37
Attention: this manual contains instructions for the exclusive use of the professionally qualied installer and/or maintenance
technician in compliance with current legislation.
The user is NOT qualied to intervene on the boiler.
The manufacturer will not be held liable in case of damage to persons, animals or objects resulting from failure to comply with
the instructions contained in the manuals supplied with the boiler.

4
1.2 - SYMBOLS USED IN THE MANUAL
Pay special attention when reading this manual to the parts marked by the symbols:
NOTE!
Tips
for the user
ATTENTION!
Possible dangerous
situation for the product
and the environment
DANGER!
Serious danger
to safety
and health
1.3 - APPROPRIATE USE OF APPLIANCE
The heat generator has been built according to the current level of engineering and acknowledged technical
safety rules.
Nonetheless, if improperly used, dangers could arise for the safety and life of the user and other persons
or damage to the equipment or other objects.
The appliance is designed to work in heating systems, with hot water circulation, for the production of
domestic hot water.
Any other use must be considered improper.
For any damage resulting from improper use, UNICAL AG S.p.A. assumes no responsibility.
Use according to the intended purposes also includes strict compliance with the instructions in this manual.
The user must be instructed concerning the use and operation of his heating system, in particular:
• Deliver these instructions to the user, as well as other documents concerning the appliance inserted in the envelope
inside the packaging. The user must keep this documentation safe for future consultation.
• Inform the user about the importance of the air vents and the ue gas exhaust system, highlighting their essential
features and the absolute prohibition of modifying them.
• Inform the user concerning controlling the system's water pressure as well as operations to restore it.
• Inform the user concerning correct temperature control, control units/thermostats and radiators for saving energy.
• Please note that, in compliance with the standards in force, the inspection and maintenance of the appliance must
be carried out in compliance with the regulations and frequency indicated by the manufacturer.
• Should the appliance be sold or transferred to a new owner or if you move and leave the appliance, always make
sure that the instruction manual accompanies it in order to be consulted by the new owner and/or installer.
The manufacturer will not be held liable in the event of damage to persons, animals or objects resulting from
failure to comply with the instructions contained in this manual.
1.4 -INFORMATION FOR THE SYSTEM MANAGER
NOTE!
For further details
refer to the Technical Information:
http://www.unicalag.it/catalogo-
prodotti/professionale-300/334/
commercial-condensazione-inox
OBLIGATION!
wear gloves
protective
DANGER!
Danger of burns!

5
1.5 - SAFETY WARNINGS
ATTENTION!
The appliance must not be used by children.
The appliance may be used by adults and only after carefully reading the operating instructions manual
for the user.
Children must be supervised so they do not play or tamper with the appliance.
ATTENTION!
The appliance must be installed, adjusted and maintained by professionally qualied personnel, in com-
pliance with the standards and provisions in force. Incorrect installation can cause damage to persons,
animals and objects for which the manufacturer cannot be held responsible.
DANGER!
NEVER attempt performing maintenance or repairs on the boiler on your own initiative.
Any work must be done by professionally qualied personnel. We recommend stipulating a maintenance
contract.
Insu󰀩cient or irregular maintenance can jeopardise the operating safety of the appliance and cause damage
to persons, animals and objects for which the manufacturer cannot be held responsible.
Changes to the parts connected to the appliance (once the appliance installation is complete)Do not modify
the following parts:
- the boiler
- the gas, air, water and electricity supply lines
- the ue gas pipe, the safety valve and the exhaust pipe
- the construction parts which a󰀨ect the operating safety of the appliance
Attention!
To tighten or loosen the screwed ttings, use only appropriate xed spanners.
Incompliant use and/or inappropriate tools can cause damage (e.g. water or gas leakage).
ATTENTION!
Indications for propane gas-red appliances
Make sure that the gas tank has been deaerated before installing the appliance.
For state-of-the-art tank venting, contact the LPG supplier or person qualied in compliance with the law requirement.
If the tank has not been professionally deaerated, ignition problems could arise.
In that case, contact the supplier of the LPG tank.
Smell of gas
Should a smell of gas be perceived, follow these safety guidelines:
- do not turn electric switches on or o󰀨
- do not smoke
- do not use the telephone
- close the gas shut-o󰀨 valve
- air out the area where the gas leakage has occurred
- inform the gas supplier or a company specialised in installation and maintenance of heating systems.
Explosive and easily ammable substances
Do not use or store explosive or easily ammable materials (e.g. petrol, paints, paper) in the room where the ap-
pliance is installed.
ATTENTION!
Do not use the appliance to support any object.
Specically, do not place any liquid containers (Bottles, Glasses, Containers or Detergents) on top of the boiler.

6
Note:
Made in ITALY
YYYY-MM
Product Fabr. - Nr - >
Body Serial Number - >
1.6 - TECHNICAL DATA PLATE
The technical data plate is adhesive and is included in the document case; it must be applied by the installer on the
outside of the casing.
The serial number of the boiler is on the riveted plaque on the front plate of the body (front right bottom side).
The CE marking
certies the compliance of the equipment with the essential
safety requirements dened in the directives and applicable
European regulations and that its functioning satisfy applicable
technical standards.
The CE marking is a󰀩xed to each piece of equipment with an
appropriate label.
The CE declaration of conformity issued in accordance with
international standards by the manufacturer, is placed in docu-
mentation envelope supplied with the product.

7
General information
ENGLISH
1.7 - GENERAL WARNINGS
The instruction booklet is an integral and essential part of the
product and must be kept by the user or system manager.
Read the warnings contained in this instruction booklet carefully
as they provide important guidelines regarding installation, use
and maintenance safety.
Keep the booklet with care for further consultation.
Installation and maintenance must be performed in compliance
with standards in force according to the instructions of the ma-
nufacturer and by qualified and certified personnel in
compliance with law.
By professionally qualified personnel we mean: personnel with
specific technical skill in the field of heating system components
for civil use, domestic hot water production and maintenance.
Personnel must have the qualifications foreseen by current
legislation.
Incorrect installation or improper maintenance can cause damage
to persons, animals or objects for which the manufacturer is not
responsible.
Before performing any cleaning or maintenance, disconnect the
appliance from the energy mains by acting on the switch of the
system and/or through the specific cut-off devices.
Not obstruct the terminals of the intake/exhaust ducts.
In case of failure and/or malfunctioning of the appliance, switch
it off and do not try to repair it or intervene on it directly.
Contact only personnel qualified in compliance with law.
Any repairs must be performed solely by personnel authorised by
Unical using original spare parts only. Failure to comply with the
above can jeopardise the safety of the appliance.
To guarantee appliance efficiency and its correct operation,
yearly maintenance must be performed by qualified personnel.
Should you decide not to use the appliance, parts entailing
potential sources of hazard must be made safe.
Should the appliance be sold or transferred to a new owner or
if you move and leave the appliance, always make sure that the
instruction booklet accompanies it in order to be consulted by
the new owner and/or installer.
Only original accessories must be used for all appliances with
optionals or kits (including electric).
This appliance is intended solely for the use for which it was
expressly designed. Any other use is to be considered improper
and therefore dangerous.

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2.2 - MAIN COMPONENTS
The XC-K3 boilers are equipped with a cylindrical furnace in
witch the combusted gases that reach the bottom take the smoke
pipes of the second turn, having reached the front, the burnt
gases are conveyed through the door into the pipes of the third
turn to reach the chamber smoke back and then to the fireplace.
During burner operation, within the boiler’s power range, the
combustion chamber is always under pressure.
For the value of this pressure see the tables
of cap. 2.4, in the column “Load losses
smoke side “.
The chimney must be calculated in such a way that
at its base is not detected any
positive pressure.
KEY
N° Description
1 Furnace
2ame sight glass
3Door with ame sight glass
4 Smoke chamber
5 Body insulation
6 Panel board
7 Smoke tubes 2 Turn
8 Smoke tubes 3 Turn
M T1 Flow
Rbt T2 Low temperature return
Rat T3 High temperature return
T4 Expansion vessel
T5 Boiler drain
T6 Burner connection
T7 Chimney connection
T8 Condensation drain
2TECHNICAL FEATURES AND DIMENSIONS
2.1 - TECHNICAL FEATURES
NOTE!
Further details in the section
‘‘Technical Information’’ on the boiler
page of the www.unicalag.it website
Smoking section tubes
Note:
For operation with oil burner, when ordering
specify it (for OIL burner). So as to foresee on
the smoke tubes the treatment with Nanoprom
coating.
4
1
2
6
3
5
Rbt T2 Rat T3 MT1 T4
T5
T8
T6
T7
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ab
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Technical features
ENGLISH
THIS PAGE INTENTIONALLY LEFT BLANK

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2.3 - DIMENSIONS
XC-K
3
DIMENSIONS [mm]
Depth Width Height
Chimney
con
-nection
Furnace
L B L1 L2 L3 L4 L5 L6 L7 L8 W A H H1 C D E Ø Ø f
1000 3760 2440 990 550 400 350 562 x x 2310 1290 1240 1630 320 376 952 1447 350 640
XC-K3 1000
11 41 12 13
31 32
42
18:28 giov30 20ott18
effettiva richiesta
76°C 84°C
generatore
10/10
modulazione
100%
INFO MENU
status
sanitaria
25°C
D
W
A
H
E
L1 L2 L3 L4 L5
Ø
Rbt T2
Rat T3
MT1T4
FRONT VIEW
UPPER VIEW
BACK VIEW

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Technical features and dimensions
ENGLISH
XC-K
3
CONNECTIONS Weight
T1 (M) T2 (R) T3 (R) T4 T5 (Sc) T6 T7 (S) T8 (Scond) G kG
PN16 inch [mm] [mm] [mm] inch
1000 DN 125 DN 125 DN 125 DN 65 G 1’’ 270 350 40 -
H1H1
L8
Ø f
Rbt T2
Rat
T3
MT1T4
T5
T7
T8
Ø p
B
L
C
SIDE VIEW SECTION
SIDE VIEW WITH CASING

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XC-K3 1250 - 3000
H
E
D
W
A
A1
L1 L2 L3 L4 L5
Ø
Rbt T2
Rat T3
MT1T4
XC-K
3
DIMENSIONS [mm]
Depth Width Height
Chimney
con-
nection
Furnace
L B L1 L2 L3 L4 L5 L6 L7 L8 W A A1 H H1 C D E Ø Ø f
1250 3293 2399 748 600 420 420 697 x x 2250 1792 1495 297 1760 297 365 1104 1643 400 730
1500 3643 2749 1098 600 420 420 697 x x 2250 1792 1495 297 1760 297 365 1104 1643 400 730
1750 3622 2650 804 600 420 550 817 x x 2500 1932 1580 302 1922 405 471 1218 1809 450 810
2000 3970 2998 1151 600 420 550 817 x x 2842 1932 1580 302 1922 405 471 1218 1809 450 810
2500 4332 3272 960 805 580 610 809 x x 2845 2369 1980 329 2457 463 621 1619 2253 550 926
3000 4738 3678 1366 805 580 610 795 x x 3250 2369 1980 329 2457 463 621 1619 2253 550 926
(*) In models: XC-K 3 2500 and 3000
the rear casing is not provided see chap. 3:11
FRONT VIEW
UPPER VIEW
BACK VIEW

13
Technical features
ENGLISH
L8
Rbt T2
Rat T3
MT1T4
T5
T7
T8
Ø p
H1H1
Ø f
B
L
C
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XC-K
3
CONNECTIONS Weight
T1 (M) T2 (R) T3 (R) T4 T5 (Sc) T6 (Ø p) T7 (S) T8 (Scond) G kG
PN16 inch [mm] [mm] [mm] inch
1250 DN 150 DN 150 DN 150 DN 80 G 1’’ 320 400 40 x
1500 DN 150 DN 150 DN 150 DN 80 G 1’’ 320 400 40 x
1750 DN 200 DN 200 DN 200 DN 100 G 1’’ 320 450 40 x
2000 DN 200 DN 200 DN 200 DN 100 G 1’’ 320 450 40 x
2500 DN 250 DN 250 DN 250 DN 125 G 1’’ 380 550 40 x
3000 DN 250 DN 250 DN 250 DN 125 G 1’’ 380 550 40 x
SIDE VIEW SECTION
SIDE VIEW WITH CASING

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2.4 - OPERATING DATA
Model: XC-K 3 1000 1250 1500 1750 2000 2500 3000
Nominal heat output (80-60°C) (80-60°C) [kW]
918 1136 1376 1606 1835 2294 2753
Nominal heat output (80-60°C) (50-30°C) [kW] 1000 1238 1500 1750 2000 2500 3000
Nominal Heat input [kW] 935 1157 1402 1636 1869 2236 2804
Combustion E󰀩ciency full load 80°C-60°C [%] 98,2 98,2 98,2 98,2 98,2 98,2 98,2
Heat efficiency full load 50°C - 30°C [%]
107,0 107,0 107,0 107,0 107,0 107,0 107,0
Heat efficiency partial load 30% del 30%: (retourn 30°C) [%]
109,0 109,0 109,0 109,0 109,0 109,0 109,0
Flue gas temperature 80°C-60°C (Tue - Tamb.) [°C] 33,0 33,0 33,0 33,0 33,0 33,0 33,0
Flue gas temperature 50°C-30°C (Tue - Tamb.) [°C] 20,0 20,0 20,0 20,0 20,0 20,0 20,0
CO2content [%] 10,3 10,3 10,3 10,3 10,3 10,3 10,3
Flue gas mass [kg/h] 1346,2 1682,0 2018,4 2354,9 2691,3 3364,1 4036,9
Combustion E󰀩ciency 80°C-60°C [%] 98,5 98,5 98,5 98,5 98,5 98,5 98,5
Combustion E󰀩ciency 50°C-30°C [%]: 99,1 99,1 99,1 99,1 99,1 99,1 99,1
Heat loss at shell 80°C-60°C [%]:
0,30 0,29 0,28 0,27 0,27 0,27 0,27
Heat loss at shell 50°C-30°C [%]
0,24 0,23 0,22 0,22 0,22 0,22 0,22
Heat loss at chimney with burner ON 80°C-60°C [%]
1,5 1,5 1,5 1,5 1,5 1,5 1,5
Heat loss at chimney with burner ON 50°C-30°C [%]
0,9 0,9 0,9 0,9 0,9 0,9 0,9
Heat loss at chimney with burner OFF [%]:
0,05 0,05 0,05 0,05 0,05 0,05 0,05
Maximum condensation production [l/h]
158,2 197,6 237,2 276,7 316,2 395,3 474,3
Maximum boiler back pressure (as standard) [mm/H2O] 67,4 ---- ---- ---- ---- ---- ----
Boiler back pressure (Smoke side pressure lost) [mm/H2O] 65,0 70,0 85,0 85,0 95,0 86,0 95,0
Head losses H2O Dt 15 [kPa] 4,0 3,2 4,5 3,8 5,0 6,0 7,5
Water boiler content [ l ] 1413 1500 2090 2375 2632 5160 5710
Max working pressure [bar] 6 6 6 6 6 6 6
Max operating temperature [C°] 100 100 100 100 100 100 100
Available chimney base pressure [Pa] 0000000

15
Technical features and dimensions
ENGLISH
3INSTALLATION
INSTRUCTIONS
ATTENTION!
This boiler is intended solely for the use for
which it was expressly designed. Any other
use is to be considered improper and there-
fore dangerous.
This boiler heats water at a temperature
lower than the atmospheric pressure boiling
temperature.
ATTENTION!
The appliances are designed to be installed
inside suitable rooms or technical spaces
only. The appliances cannot be installed or
operate outdoors. Outdoor installation can
cause malfunctioning and be dangerous.
Choose specifically designed appliances for
outdoor installation.
Before connecting the boiler, have profes-
sionally qualied personnel:
a) Thoroughly wash all the piping of the sys-
tem to remove any residues or impurities,
which could jeopardise proper operation
of the boiler.
b) Check that boiler is set up to operate with
the available type of fuel.
This can be seen written on the package
and on the technical feature plate;
c) Check that the chimney/flue has an
appropriate draught, without any bottle-
necks, and that no exhausts from other
appliances are inserted, unless the ue
has been implemented to accommodate
several utilities according to specific
standards and regulations in force. Only
after this check can the tting between
the boiler and chimney be mounted;
ATTENTION!
If there is dust and/or if there are
aggressive/corrosive vapours present in
the installation room, the appliance must
be protected suitably and must be able to
operate independently from the air in the
room.
ATTENTION!
The appliance must be installed by a qualified
technician with the technical-professional
requirements according to law which, under his
own responsibility, guarantees compliance
with standards according to good practice
rules.
ATTENTION!
Mount the appliance respecting the minimum
distances required for installation and main-
tenance.
The boiler must be connected to a central
heating system.
3.1 - GENERAL WARNINGS
3.2 - STANDARDS FOR INSTALLATION
It must be installed by a professionally qualied technician, who
shall take the responsibility of observing all local and/or
national laws published in the o󰀩cial journal, as well as
the applicable technical standards.
NOTE!
For further details relating to the stand-
ards, rules and regulations for safe in-
stallation of the thermal unit, refer to the
section "Technical Information" on the
boiler page of the www.unicalag.it website

16
3.3 - PACKAGING
XC-K 3 boilers are supplied complete with the door
and smoke chamber assembled, while the casing
and insulation are included in separate cardboard
packs.
Before starting installation, make sure that the length and width
of the boiler body received correspond respectively to the di-
mensions L and W of the boiler you have ordered
The casing of boilers complete with insulation mattresses, is
contained in boxes.
Boxes
n.3 XC-K 3 1000
n.3 XC-K 3 1250 - 1500
n.3 XC-K 3 1750 - 2000
n.4 XC-K 3 2500 - 3000
The control panel is optional and if required it is packed with its
own cardboard and placed inside the furnace,
as accessories positioned inside thefurnace you will also find:
1 box containing hydraulic connection anges, with
relative gaskets and bolts (where included).
- ceramic bre cord to insulate between burner blast tube and
door.
Keep the packaging material (plastic bags, etc.) out of the reach
of children as they are potential sources of danger.
Unical will not be held liable for damage to persons,
animals or objects due to failure to comply with the
above instruction.
Inside the furnace is contained:
Pouch with the following documentation:
- Manager operating instructions booklet
- Instruction booklet for the installer and maintenance
engineer
- 2 Spare parts form
- Certicate of conformity
- Testing certicate
Accessories box containing:
- 5 bends + a T + a plastic condensate draining cap
- Condensate drain siphon pipe 1 m.
- Protect all parts against impacts if they are
to be transported.
OBLIGATION!
wear protective gloves
3.3.1 - HANDLING
The boiler must be handled by lifting by the upper
hooks, or by translation with rollers placed under
the sturdy base side.

17
Technical features and dimensions
ENGLISH
3.4 - POSITIONING IN BOILER
ROOM
The boiler must be installed in compliance with standards and
prescriptions in force.
The room must be well ventilated by openings with a total surface
no less than 1/30 the surface of the boiler room, with a minimum
of 0.5 m².
The ventilation openings must be permanent, communicate
directly with the outside and be positioned high or low according
to standards in force.
The location of the ventilation openings, the fuel supply circuits,
electric energy supply and lighting must comply with current legal
provisions in relation to the type of fuel used.
It is recommended to install the boiler as close to the chimney
connection as possible.
To make it easier to clean the smoke circuit, in front of the boiler,
there must be a free space no less than the length of the boiler
body and, in any case, never less than 1300 mm. Check that
with the door opened 90°, the distance between the door and
the adjacent wall is at least the length of the burner.
The boiler can be placed directly on the oor as it is equipped
with a base.
However it is useful to provide a at, level cement plinth capable
of bearing the weight of the boiler full of water.
When positioned on the plinth, the dimensions must be at least
B x A (see dimensions table).
When installation has been performed, the boiler must be perfectly
horizontal and stable (to reduce vibrations and noise).
Comply with the minimum overall dimension
distances in order to execute normal
maintenance and cleaning operations.
CLEARANCE mm
XC-K 3 W L L9 H
1000 1300 3700 1000 1500
1250 1300 3200 1000 1500
1500 1300 3200 1000 1500
1750 1300 3600 1000 1500
2000 1300 3900 1000 1500
2500 1300 4300 1000 1500
3000 1300 4700 1000 1500
WW
H
H
LL9
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18
Length Burner
dimension
Door
drilling
Model Ø b L.b
(min)
Ø p
(mm)
L.p
(mm)
XC-K 3 1000 250 300 270 171
XC-K 3 1250 - 1500 300 350 320 207
XC-K 3 1750 - 2000 300 390 320 278
XC-K 3 2500 - 3000 360 400 380 310
3.5 - BURNER
The burners operating with the XC-K3 boilers must have the EC
certication comply with the local and / or national regulations
in force published in the official journal.
3.5.1 - CHOOSING THE BURNER
he correct choice and adjustment of the burner are fundamental
for optimal operation of the boiler and therefore must be done
carefully and not underestimated.
The burner must be chosen verifying that its ring rate (fuel
capacity - combustion chamber pressure) is compatible with the
same features declared for the boiler.
Remember that pressure drops on the ue side of the boiler, na-
mely combustion chamber backpressure, refer to zero pressure
at the base of the chimney.
It is also recommended that the burner blast tube be no shorter
than the minimum dimension shown in the following table and
that the ame which must be implemented be suitable for the
characteristics of the combustion chamber.
In order to take advantage of the whole heat exchange surface
of the blind bottom furnaces, use burners capable of providing
a “long and narrow” ame in any operating condition, namely
even at the minimum output when controlling two or more stages
or modulating.
Flames which are too short cause overheating in the front of
the furnace and combustion products, not su󰀩ciently cooled,
entering the smoke pipes at too high temperatures can seriously
damage the generator.
The manufacturing companies of the burners can supply the
dimensions of the ames which their appliances develop.
Ø b
L.b
L.p
Ø p
22
Note: For maintenance manager
For a good boiler operation, it is advisable to
calibrate the burner to a minimum Power (Qmin)
30% of the rated Power (Qn).
3.5.2 - INSTALLING THE BURNER
The burner must be mounted to the door of the
boiler guaranteeing perfect sealing of the
combustion products.
The burner is supplied with a piece of ceramic
fiber cord which must be placed on the blast
tube of the burner to fully seal the space
between the blast tube and the slot in the door.
Make sure that no gaps remain between the blast tube and the
slot on the refractory material inside the door.
Should a cone larger than the diameter of the blast tube be
mounted, it must be removed before mounting the burner on
the support plate and put back afterwards.
With the burner mounted, check that the electric cables are long
enough to allow the door to open 90°.
For gas-fired burners, flexible hoses cannot be used for
connections. Therefore it must be possible to disconnect the
final section of the gas adduction tube by means of a threaded
or flanged joint.

19
Technical features and dimensions
ENGLISH
1
2
3.6 - FURNACE DOOR: ADJUSTMENT,
OPENING AND CLOSING
3.6.1 - XC-K 3 BOILERS
For all these models, the door is hinged and fixed according to
figure In these cases, the door is mounted with four equal hinges:
the two on the left side are normally used as rotation hinges
(from right to left), while the two on the right side are used as
closing hinges; the door is then secured with 4 nuts.
It will be exactly the opposite when the door is opened from the
left to the right.
To invert rotation, just move the rear locknuts to the opposite side.
C
C
C
C
B
A
C
B
A
On the door are possible the following adjustments model by
model
XC-K 3 1000 only adjustment B - C
XC-K 3 1250 ÷ 2000 adjustment A - B - C
XC-K 3 2500 ÷ 3000 adjustment A - B - C
A) Vertical adjustment: only by inserting suitably thick washers
below the hinge which the door turns on.
B) Crosswise rotation: loosening the hinges xed on the front
plate of the boiler and moving them sideways.
C) Axial rotation: screwing di󰀨erent tightening nuts.
3.5.3 - CONNECTING FLAME SIGHT
GLASS TO BURNER
The flame sight glass is provided with a 1/8” threaded connection
(pos. 1) upon which a 9 mm pressure test nipple is mounted.
It can be used with a silicon tube to measure the backpressure
in the combustion chamber.
In place of this test nipple, which must be kept, an appropriate
fitting will be mounted to connect the flame sight glass directly
to the pressure chamber downstream the burner fan by means
of a copper tube (pos.2).
The air blown by the fan will conveniently cool the sight glass
and keep it from blackening.
If the cooling tube is not connected to the sight glass, it could
break.
ATTENTION:
the flame sight glass can be very hot; there-
fore pay the utmost attention.
IMPORTANT NOTE
Before opening the door of the furnace, take the
following
safety measures:
- Close the fuel supply to the burner.
- Cool the boiler o󰀨 by having water circulate and then discon-
nect electrical power.
- Place a sign on the boiler with the following text:
DO NOT USE, BOILER MAINTENANCE UNDERWAY,
OUT OF SERVICE.

20
3.8 - CONNECTION
Danger!
The gas connection must be carried out only by
a qualied installer who must respect and apply
that foreseen by relevant laws in force in the local
prescriptions of the supply company. Incorrect in-
stallation can cause damage to persons, animals
and objects for which the manufacturer cannot be
held responsible.
If you smell gas:
a) Do not operate electric switches, the telephone
or any other object that may cause sparks;
b) Immediately open doors and
windows to create air current
to purify the room;
c) Shut the gas cocks.
d) Ask for the intervention of professionally
qualied personnel.
The mains pressure must be within 0.5 and 6 bar
(in the event of greater pressure install a pressure
reducer).
Attention!
Do not mix the heating water with incorrect
concentrations of antifreeze or anti-corrosion
substances! This could damage the gaskets
and cause noise during operation.
Unical will not be held liable for damage to
persons, animals or objects due to failure to
comply with the above instruction.
XC-K 3 CONNECTIONS
G
Gas Inlet
[Inch]
M (T1)
Flow
[DN]
R (at / bt)
(T2 - 3) Return
[DN]
T4
Expansion vassel
[DN]
T5
Drain Boiler
[Inch]
T7
Flue gas exhaust
[Ø mm]
T8
Condensation drain
[Ø mm]
1000 X DN 125 DN 125 DN 65 G 1’’ 350 DN 40
1250 X DN 150 DN 150 DN 80 G 1’’ 400 DN 40
1500 X DN 150 DN 150 DN 80 G 1’’ 400 DN 40
1750 X DN 200 DN 200 DN 100 G 1’’ 450 DN 40
2000 X DN 200 DN 200 DN 100 G 1’’ 450 DN 40
2500 X DN 250 DN 250 DN 125 G 1’’ 550 DN 40
3000 X DN 250 DN 250 DN 125 G 1’’ 550 DN 40
11 41 12 13
31 32
42
Selez.
ServizidiRiscaldamento
SelezionalaFunzione
Esci
T4 MT1 Rat T3 Rbt T2
T7
T5 T8
G
3.7 - FLUE GAS EXHAUST PIPE
CONNECTION
To connect the ue gas exhaust pipe, local and national stand-
ards must be observed.
It is recommended to insulate the pipe connecting to the chimney
to reduce heat loss and noise.
Along the section connecting the boiler to the
flue there must be suitable points for measuring
flue gas temperature and analysing combustion
products.
Use only exhaust pipes suitable for the type of fuel used.
The supplier will have no contractual or extra-contractual
liability for damage caused due to incorrect installation and
use and anyway failure to comply with the instructions pro-
vided by the manufacturer.
When performing replacement installations, ALWAYS
replace the flue gas exhaust accessory as well.
The flue must comply with standards in force.
Warning!
If it is not necessary to have the 2 returns
in the system, ever use the low temperature
return Rbt (T2).