KOTLOSPAW DuoKo 15 User manual

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„KOTŁOSPAW”
63-300 Pleszew
ul. Szenica 38
Operation and maintenance manual
Operation and assembly instruction
Central heating boilers
with pellet and eco-pea coal burner
„DuoKo” ……... kW
Serial no. …………….
Before installing and operating the boiler, read this manual carefully.
WARNING!
Incorrect protection of the boiler may cause serious damage to the boiler and is
dangerous for the user
The following protections should be used for DuoKo boilers
- in open-loop system according to PN-91/B-02413
- in closed-loop system according to PN-EN 12828
WARNING: You received the first version of manual, in case of any doubts or other
suggestions regarding the information in this manual, please contact us at [email protected]
Always install and operate the boiler in accordance with applicable regulations and standards
Edition 1
May 2018

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TABLE OF CONTENT
1.INTRODUCTION.................................................................................................................................... 4
1.1. General information..................................................................................................................... 4
1.2. General terms of use and warranty conditions............................................................................ 4
1.3. Delivery specification ................................................................................................................... 5
1.4.Transport of boiler ........................................................................................................................ 5
2. DESCRIPTION AND PURPOSE.............................................................................................................. 5
3. TECHNICAL AND OPERATING FEATURES............................................................................................ 6
4. CHOOSING BOILER FOR HEATING SYSTEM ........................................................................................ 6
4.1. Rates of heat demand for residential buildings. .......................................................................... 6
5. TYPES OF FUEL..................................................................................................................................... 6
6. CONSTRUCTION DESCRIPTION ........................................................................................................... 7
6.1. Types of boiler protections......................................................................................................... 10
6.2. Safety systems of the burner ..................................................................................................... 10
7. CONNECTING BOILER TO HEATING SYSTEM.................................................................................... 10
7.1. Place of installation .................................................................................................................... 10
7.2. Flue gas installation.................................................................................................................... 11
7.3. Central heating system............................................................................................................... 12
7.4. Protecting boiler in open-loop system....................................................................................... 12
7.5. Protecting boiler in closed-loop system..................................................................................... 16
7.5.1. Protection of boiler.............................................................................................................. 16
7.5.3. Blowoff-drain and filling valve........................................................................................... 16
7.5.4. Requirement regarding assembly ........................................................................................ 17
7.5.5. Safety requirements............................................................................................................. 17
7.5.8. Requirements for closed-loop system operation ................................................................. 20
7.5.9. Guidelines for t choosing expansion vessels (closed-loop systems) according to PN-EN
12828: 2003 –attachment D.......................................................................................................... 20
7.5.10. Calculation of the expansion vessel size ........................................................................... 21
7.5.12. Causes of residual risk and how to eliminate it. ................................................................... 24
8. ELECTRICAL INSTALLATION............................................................................................................... 24
9. FILLING WITH WATER ....................................................................................................................... 25
10. LOW-TEMPERATURE CORROSION.................................................................................................. 25
11. TECHNICAL-OPERATIONAL DATA................................................................................................... 25
12. COMMISSIONING OF THE BOILER .................................................................................................. 27

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12.1. Pre-testing ................................................................................................................................ 28
12.2 Firing up..................................................................................................................................... 28
12.3 Fuel refilling............................................................................................................................... 28
13. POWER ADJUSTMENT..................................................................................................................... 29
14. ESSENTIAL CONDITIONS FOR SAFE OPERATION............................................................................ 29
15. BOILER OPERATING INTERRUPTION- MOST FREQUENTLY OCCURRING PROBLEMS AND HOW TO
SOLVE THEM. ........................................................................................................................................ 29
16. CLEANING AND MAINTENANCE WORKS........................................................................................ 31
17. FIRE SAFETY CONDITIONS............................................................................................................... 32
18. EMERGENCY STOP .......................................................................................................................... 32
19. SHUTTING DOWN THE BOILER ...................................................................................................... 33
20. FINAL PROVISIONS.......................................................................................................................... 33
21. ENVIRONMENTAL PROTECTION..................................................................................................... 34
23. CONDITIONS FOR SAFE OPERATION OF BOILERS.......................................................................... 35
24. WARRANTY CONDITIONS............................................................................................................... 35
25. WARRANTY CARD........................................................................................................................... 41
26. BOILER COMMISSIONING PROTOCOL............................................................................................ 42

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1.INTRODUCTION
1.1. General information
The Operation and Maintenance Manual is a manual for solid fuel boilers with automatic fuel feeding
for users of central heating water-based boilers with a DuoKo-type pellet and eco pea coal burner.
Familiarizing with the Operation and Maintenance Manual, which contains information about the
construction, installation, and use of boilers is necessary for their proper and safe functioning. The
use of a modern and high-class feeder and regulator is important for automatic and trouble-free
operation. Information about the burner and regulator for the boiler provided in this Operation and
Maintenance Manual are general, while the detailed instructions for the use of these devices are to be
found in the manuals of these devices, which are an integral part of the boiler manual.
Before installing and operating the boiler, it is necessary to:
- thoroughly read this Operation and Maintenance Manual of the boiler and burner, as well as other
manuals of devices/equipment of the boiler.
- check the content of the package, compare the data on the identification plate with the warranty
card,
- check if the boiler has not been damaged during transport.
The boiler is equipped with an identification plate located in a visible place, which contains the
following information:
- name and address of the manufacturer,
- trademark and type of boiler,
- number and year of production,
- nominal thermal power,
- boiler class,
- maximum allowable working pressure in bar,
- maximum working temperature in °C,
- water capacity in liters,
- electrical supply [V, Hz, A] and power consumption in [W].
- fuel class according to PN-EN 303-5 standard.
The "DuoKo" boiler is equipped with a modern burner for feeding and burning pellet or eco pea coal
and a combustion process regulator. Unique solutions were used, and the innovative technology of
hypertensive combustion eliminates the problem of back burning. Such solutions improve the
combustion process and cause less fuel consumption. They also help to maintain a comfortable
temperature in heated rooms. Burner installation and connection of central heating system devices to
the regulator and the boiler should be made by the manufacturer or his authorized and trained service
technician.
There is a warranty for the boiler. The detailed warranty conditions are specified in this manual and
the attached warranty card.
The boiler is a heating device in which, despite numerous technical protections as well as
recommendations and information on safe use, there is always a potential risk of getting burn and fire.
Therefore, personnel should always keep the basic safety rules in mind and be particularly careful
before taking any action.
Declarations of compliance of the feeder, controller, and other devices constituting the boiler
equipment are an integral part of this Operation and Maintenance Manual.
1.2. General terms of use and warranty conditions
DuoKo boilers are designed for installation in closed rooms - boiler rooms. The use of boilers for other
purposes and ways of use not in accordance with the Operation and Maintenance Manual are not
allowed. Boilers should be used, operated, and repaired only by adults. Persons operating boilers over
50 kW must have valid permissions to operate them (Regulation of the Minister of Economy, Labor
and Social Policy of April 28, 2003, Journal of Laws of 2003, No. 89, item 828). The obligation of

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operating and responsibility for safety is on the user, who should meet all requirements specified in the
Operation and Maintenance Manual. In order to commission the boiler, carefully read the operating
instructions for the burner, controller, and other equipment in order to understand the specifics of their
operation, and strictly follow the provided terms of use. Accident prevention regulations and all basic
occupational health and safety regulations must always be followed.
WARNING!
Disturbances and irregularities in the operation of the boiler resulting from ignorance of the provisions
of the Operation and Maintenance Manual are not subject to a complaint.
In particular:
- incorrect selection of the boiler size for the building being heated,
- incorrect installation of the boiler and central heating system,
- using the wrong fuel (type, granulation, calorific value),
- protection in the open-loop system of the boiler not compliant with PN-91/B-02413
- protection in the closed-loop system of the boiler not compliant with PN-EN 12828
- use of a non-compliant chimney,
- failure to perform cleaning and maintenance works on the boiler,
- mechanical damage,
- improper boiler room ventilation.
1.3. Delivery specification
The boiler is delivered as a compact of the body, the fuel container, and equipment. The body of the
boiler is connected to the equipment and sheathed with mineral wool thermal insulation, covered with
a protective jacket of steel sheet constituting the aesthetic built-up of the boiler. An integral part of the
boiler is a pellet burner, fuel container, pellet feeder, control device, the Operation and Maintenance
Manual, and warranty cards.
The delivery consists of:
- boiler body –heat exchanger with complete insulation
- fuel container
- pellet and eco pea coal burner
- pellet and eco pea coal feeder
- fan integrated with burner
- microprocessor controller
- thermometer
- operating instructions of boiler feeder and controller
- tools to operate the boiler
1.4.Transport of boiler
When transporting the boiler, it should be secured against moving on the platform of the vehicle using
straps, wedges, and wooden blocks attached to the platform of the vehicle. The boiler should be
transported in an upright position, small boilers preferably on pallets. Lifting and lowering the boiler
should be done by means of transport handles and slings using mechanical lifts and cranes.
2. DESCRIPTION AND PURPOSE
Central heating water-based DuoKo type boilers for solid fuels equipped with a pellet or eco pea coal
burner and a high-class system of automatic regulation and control of the combustion process. They
are intended for central heating installations in various types of facilities and domestic hot water
production. They have been designed and made as boilers with the low heat output and are intended
mainly for small buildings and single-family houses. They can work in gravity or pump systems.
The boilers guarantee much greater comfort of operation in comparison to traditional boilers, due to
the use of an automatic fuel feeding system and firing up. The modern design of the heat exchanger
ensures very high thermal efficiency at a small size, and the use of renewable fuels helps to protect the

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natural environment. As fully automatic boilers, they are an economical alternative to both gas, oil,
and coal boilers below class 5.
3. TECHNICAL AND OPERATING FEATURES
The boilers have a simple integrated design. The operation of the boiler is simple and easy due to the
use of an automatic and controlled fuel feeding system, which enables, among others, smooth
adjustment of the boiler heat output and obtaining the outlet water temperature according to your
needs. The basic operation consists of controlling, loading fuel to the container, and removing small
amounts of ash.
WARNING!
DuoKo boilers should be secured:
- open-loop system, according to PN-91/B-02413. Heating and district heating. Protection of open-loop
water-based heating systems. Requirements.
- closed-loop system, according to PN 12828. Heating systems in buildings. Designing water-based
central heating systems.
Boilers meet the requirements of EU directives when it comes to product safety confirmed by a
declaration of conformity and having the "CE" marking.
4. CHOOSING BOILER FOR HEATING SYSTEM
Calculated heat demand due to penetration losses, heat for ventilation, and domestic hot water needs
should be taken into account to choose the boiler correctly. The designer should develop the heat
balance of the building in accordance with applicable standards.
WARNING!
The manufacturer is not responsible for the incorrectly chosen boiler.
4.1. Rates of heat demand for residential buildings.
To determine the estimated heat demand for heating of the residential building, the average values of
the following heat demand rates can be used.
- q=120-110W/m² - for buildings with medium insulation (walls made of autoclaved aerated
concrete, multi-layer without thermal insulation, double windows)
- q=100-80W/m² - for well-insulated buildings (insulated walls made of autoclaved aerated concrete,
insulated windows with multiple glazed panels, "warm" floors).
5. TYPES OF FUEL
For version with the pellet burner the only fuel is pellet. After each change or delivery of fuel, it is
absolutely necessary to carry out the so-called "FEEDER TEST" as it a significant impact on the
proper and trouble-free operation of the device.
Detailed requirements regarding the quality and properties of pellet fuel are specified in the manual of
the burner used for the boiler.
When choosing fuel, particular attention should be paid to the possible content of mechanical
impurities in the fuel in the form of stones or other non-flammable inclusions deteriorating the
quality of the combustion of fuel from uncertain sources. Pellets must be delivered and
transported in conditions of absolute dryness. Due to the moisture of granules, they lose a lot
of quality, and it's very difficult to burn. Pellets should be stored in dry rooms, and it should
be insulated against external factors.
The user should always choose fuel with the highest physical and chemical parameters in
order to fully use the boiler's construction and operational values.

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For the version with an eco-pea coal burner, the basic fuel is hard coal in form of dry pea coal,
energy pea with the parameters specified in the table below.
In the event of using poor quality fuels, you should take into account the difficulties with
combustion and reduction of boiler efficiency, as well as earlier destruction of the boiler and
loss of warranty. Particular attention should be paid to the content of chlorine and its
compounds in fuel and water, as they cause faster corrosion of the boiler.
Value/type of fuel
Pellet
Eco-pea coal
m.u
Calorific value
>17
>28
MJ/kg
Type/class
C1
31 or 31.1
-
Fraction
granulate
granulate
-
Moisture
≤12
≤11
%
Ash content
≤0,5
≤7
%
Diameter
6±1
5±25
mm
Length
3,15 - 40
-
mm
Bulk density
600-700
750-800
kg/m3
Content of culm
≤1
<10
%
Sulfur content
-
<0,6
%
Ash softening temperature
-
>1150
ºC
Agglomerating capacity
-
RJ<10
-
Volatile matter content
> 30
%
WARNING!
Use only fuel, the type and properties of which are specified in the manual of the burner
(Operation and Maintenance Manual) that was used for the boiler. In the case of using lower-
quality fuels, the user may have difficulties in burning, and the efficiency of the boiler will be
lower. Using lower-quality fuel may also cause premature destruction of the boiler and
burner. The boiler is not intended for burning waste and other fuels.
6. CONSTRUCTION DESCRIPTION
The boiler is made of several modules - the body of the heat exchanger, fuel container, burner
with fuel feeder as well as controller, and thermal insulation, which all create an integral
device.
The body has a box design and is made in a bent-welded version.. It consists of a furnace with
an ash pan and a convection part and is additionally equipped with a door, a flue, nozzles, and
an ash drawer. The furnace and ash tray constitute one chamber in which a burner with a
spiral fuel feeder is located, together with a drive and a fan.
The feeder's task is to supply fuel to the burner head and combustion in the furnace.
Under the burner, there is an ash tray. The air necessary for the combustion process is
supplied by a blower fan connected to the burner and supplies the air into the fuel zone. The
controller regulates the operation of the boiler and the fuel supply system. Directly around the
furnace, there is a convection part - a heat exchanger.
The convection part is connected to the flue via a vertical convection ducts.
Construction and dimensions of boilers are shown in Fig. 4. The boiler design allows for
cleaning the heat exchange surfaces periodically, furnace, ash pan, ducts through the furnace

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and ash pan doors as well as cleaning the convection ducts. All closed hatches are heat-
insulated doors or covers. The boiler also has thermal insulation.
The mechanical and feeder drive parts are covered and do not endanger the safety of
operating.
Furnace
The furnace consists of a combustion chamber and an ash tray. Around the combustion
chamber, there is a water jacket.
At the front of the furnace, there is a furnace door to which the burner is mounted.
Convection part
The convection part consists of a horizontal (shelves) heat exchangers located in the water
space above the furnace. The flue gas from the combustion chamber flows through horizontal
ducts to the vertical flue which can by optionally located at the back of the boiler. The
reversing chambers have an expansion structure, which causes the slowdown and change of
direction of the flue gas flow and they work as a settling chamber. The construction of a heat
exchanger with several sections results in a developed heat exchange surface. Changing the
direction and speed of flue gas flow affects the precipitation of thicker volatile fractions (dust)
and reduces their emission into the environment. As a consequence of this solution, a properly
directed flue gas circulation influences the intensification of heat exchange and the high
efficiency of the boiler.
Front door
The front door is located at the front of the boiler, and they are closing the entire space of the
furnace, ash tray, and convection part. The door has handles for safe opening and ensures
tightness when closed. One opening of the door allows access to the burner and the internal
space of the boiler (furnace, ash tray), which makes it easy to operate, clean the furnace and
remove ash and other impurities remaining after burning and cleaning the boiler.
WARNING!
It is not allowed to open the furnace door when the boiler is working.
Clean-out hatch
The clean-out hatch is located on the back of the boiler in the area of the reversing (settling) chamber.
The clean-out hatch with a partition works as a flue gas swirler. After opening the clean-out hatch, we
have access to clean the settling chamber.
Thermal insulation and housing
Thermal insulation and housing are made of mineral wool placed in steel sheet cassettes, either coated
or painted on both sides, ensuring a safe temperature of the external surface and a closed housing and
an aesthetic appearance.
Flue
The flue is located in the upper part of the boiler, and it is the element that is connecting the boiler
with the chimney.
The outlet from the flue as standard is cylindrical and directed upward or optionally backward.
The flue for safety reasons may not have a flue gas damper.
Nozzles
The boiler has threaded supply and return nozzles as well as drain and measuring nozzles. The boiler
has 2 supply nozzles at the top and 2 return nozzles at the bottom, led out from the back of the boiler

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on the left and right side, to be used depending on the needs. One of the return nozzles should be used
in the system as a drain nozzle. In the upper part of the boiler, there are control and measurement
nozzles of a temperature sensor, STB.
1x1/2” Safety valve female thread SYR
2x1” Supply female thread
Control box
2x1” return female thread
Burner with feeder
The burner with the feeder is mounted in the furnace of the boiler. The feeder's task is to feed fuel
from the container to the burner head located in the furnace. The fuel is fed through a special spiral
feeder driven by a gear motor.
The pellet and eco pea coal burner used is characterized by:
- safety when it comes to temperature control and back burning
- combustion system reliability
- modern control system when it comes to firing up (pellet), flame control using power control.
Fuel container
The fuel container is made of steel sheet and shaped in a way to ensure that the fuel slides down. It is
closed with a tight lid, protected against accidental closing by gas cylinders.
Keep the right fuel level of at least 1/4 of the bin's capacity.
Microprocessor controller
The microprocessor controller is mounted in the front in the housing of the boiler. Through a system
of sensors installed in the boiler and burner, it controls the fuel feeder operation, according to the
boiler water temperature set by the user in accordance with the current demand and not exceeding the
allowed value specified in the operating manual. The regulator is also equipped with sensors for the
emergency shutdown of the boiler in the event of emergencies.
The controller is a modern electronic device designed to control the operation of the boiler, taking into
account the specificity of pellet and eco pea coal combustion.
It can control the operation of the direct central heating circuit, the domestic hot water circuit, and the
operation of several heating circuits. The preset temperature of heating circuits can be set based on

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weather sensor readings. The possibility of cooperation with room thermostats, separate for each
heating circuit, contributes to maintaining the comfort temperature in heated rooms.
6.1. Types of boiler protections
The controller is equipped with emergency sensors and shuts down the boiler and signals
emergencies with a light or sound on the desktop in the event of:
- exceeding the max. boiler water temperature,
- lack of fuel it shuts down the entire system and extinguishes the burner,
- reversion of flame/ember makes it impossible to feed fuel to the burner,
The STB thermal protection is a water temperature limiter, which is making sure that the
water temperature is not exceeded by shutting down the boiler off completely when the
maximum allowed temperature is reached. After the use of STB protection, the limiter can
only be restarted manually, which conditions are restarting the boiler and its further operation.
If the burner is restarted, it is necessary to check the reason for the shutdown caused by the
boiler overheating, assess it, and take appropriate action to eliminate the cause.
6.2. Safety systems of the burner
The burner is equipped with the following safety systems that effectively protect the user
against back burning. The primary protections include:
- burner temperature sensor, which after detecting the heating medium temperature above
90°C, goes from operating mode to shutting down mode.
- flexible loading pipe (for pellet), which is an elastic connector between the external feeder
and the burner itself. Its main task is to supply fuel to the burner; in addition, it also has the
function of protection against the back burning. High temperatures may result in the burning
of the pipe, preventing further feeding of fuel.
7. CONNECTING BOILER TO HEATING SYSTEM.
Before connecting the boiler to the heating system, carefully read the operating instructions
and check if all components are working and the boiler is fully equipped and complies with
the delivery specification. DuoKo boilers should be installed in accordance with the Operation
and Maintenance Manual of the boiler, boiler room design, requirements for ventilation and
flue gas discharge, and the quality of boiler feed water. The location and equipment of the
boiler room should comply with the standards for "Solid fuel boiler rooms."
WARNING!
For the system to be safe, all boiler installations should be made with special care, using the
current state of knowledge and technology in accordance with recognized engineering
practice. The boiler must only be secured:
- according to PN-91/B-02413 –open-loop system
- according to PN 12828 –closed-loop system.
7.1. Place of installation
Transporting the boiler to its place of installation, due to its size and weight, should be carried
out with extreme caution. To move the boiler, pipes laid on the floor can be used. The action
should be managed by one responsible person, preferably an experienced installer, who will
install the boiler. This person should be obliged to choose the method and organization of the

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boiler positioning and installation. If necessary, you may remove the burner and bin that is
located on to the body of the boiler.
The way of moving and positioning the boiler should be adapted to the conditions of a room
and surface, obstacles, inclines, etc. Particular attention should be paid to the safety of legs
and arms and the possibility of the boiler tipping over. The boiler basically does not require a
foundation, and it is allowed to place the boiler directly on a non-flammable floor. It is
recommended that the boiler is installed on the platform, a plinth approx. 5÷10 cm above the
floor. The boiler should be carefully leveled, and the strength of the ceiling and the floor on
which it is placed should be checked for the weight of the boiler with water. The boiler should
be placed on the floor made of non-flammable materials.
WARNING!
The boiler should be easily accessible from all sides, especially from the front of the boiler
and from the side of the boiler, so that objects or walls of the building surrounding the boiler
do not obstruct fuel loading, cleaning of the burner, furnace, ash tray, convection ducts and
removal of soot.
One of the conditions for good operation of the boiler is a sufficient supply of fresh air.
Therefore the boiler room should have appropriate gravitational vents above the floor and
under the ceiling. The room in which the boiler is located should meet the ventilation
requirements for this type of facility and comply with regulations and standards.
WARNING!
Mechanical flue gas ventilation is not allowed in the boiler room.
7.2. Flue gas installation
The boiler flue should be connected to the chimney with an additional steel connector up to
400 mm long rising upwards and the diameter not less than the diameter of the flue. The
connection with the chimney must be tight and have closed inspection holes, enabling the
cleaning of the flue and the connection. It is not recommended to connect two or more boilers
to a common collector. The dimensions of the chimney are very important for the correct
operation of the boiler. The height and diameter should provide the required chimney draft,
which has a special impact on the correct operation of the boiler. Incorrect dimensions of the
chimney duct, height, and diameter of the chimney opening are the reason for insufficient
draft, which can lead to faulty boiler operation. The height of the chimney should take into
account the conditions of the boiler room location in relation to other buildings and objects. In
the case of an uninsulated steel chimney, its diameter should be increased by 20%. The
chimney should be at least150 cm above the highest edge of the roof. The chimney flue
should be free from other connections. The walls of the chimney channel should be smooth,
tight and without deflections. To ensure good draft, the chimney and boiler should be
thoroughly heated and dried before heating (or after breaks in heating).
The following formula can be used to select the chimney:
0,003 x Q x 0,86
F = ----------------------- (m²)
√h
where:
Q -is the thermal power of boilers connected to the chimney flue [kW]
h -chimney height measured from the grate level to the outlet [m].

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The draft required for particular boilers is specified in Table 2. The required draft should be supported
by the designer with calculations and choosing chimney duct parameters (diameter and height), taking
into account climatic zones and terrain conditions. A regulator or draft generator is recommended.
Flue gas condensation does not occur in normal operation and work of the boiler. It is recommended
that the chimney ducts be made of materials resistant to harmful chemical compounds, including acids.
In already built chimneys it is recommended to use chimney inserts made of stainless steel. To avoid
draft interruptions, chimney cowls are recommended.
WARNING!
The chimney installation should meet the requirements of applicable regulations and standards when it
comes to safe drainage. A chimney sweep should evaluate the technical condition and confirm with
the appropriate protocol the draft and chimney parameters required for a particular boiler.
7.2.1. Basic requirements for chimneys
The chimney must first of all be safe and in order to meet this basic parameter, it is necessary to
comply with certain requirements of the Construction Law, which include
-safety of construction
-fire safety
-safety of use
-appropriate hygiene and health conditions and environmental protection
-energy saving
To meet these requirements, a chimney must be built:
-by a person with the required construction qualifications
-from materials with the required approvals for the construction of chimneys
-the chimney must meet the requirements for chimney draft
-the chimney must be inspected by an authorized chimney sweep before its use
7.3. Central heating system
After positioning the boiler and connecting it to the chimney, connect the boiler to the heating system.
To do so, follow these steps:
- connect the boiler's power nozzle/connector with the central heating system in a place intended for
this,
- connect the boiler return nozzle as above,
- fill the central heating system with water
- connect the control device and check the electrical installation,
- if a central heating circulation pump is used (manufacturer's recommendation), make the pump
connection with the so-called "gravity bypass", enabling the use of the central heating system in the
event of a possible failure of the pump.
7.4. Protecting boiler in open-loop system
The most important requirements for a DuoKo type boiler protected in an open-loop system with an
expansion vessel
- an open-loop system expansion vessel with a capacity calculated in accordance with 2.5.1 PN-
91/B-02413,
- safety pipe with a diameter depending on the boiler heat output according to table 1,
-expansion, signaling, overflow, and venting pipes, as well as circulation pipes, allowing
maintaining proper temperature in the vessel and protected against freezing. On safety pipes, the use of
valves and gate valves is not allowed. The pipe should be free from constrictions and sharp angles
along its entire length.
- if it is impossible to route the safety pipes in the shortest and easiest way to the vessel, the way
they are routed as well as the diameter should be in accordance with PN-91/B-02413.
NOTE!

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The manufacturer is not responsible for incorrect boiler operation caused by a faulty and non-
compliant heating system.
The refilling of the system with water can only be caused by losses due to water evaporation. Frequent
refilling of water indicates leakage in the system and is not allowed. This may cause the boiler scale,
which can lead to permanent damage to the boiler. In the case of mounting into the existing central
heating system check technical condition (for example check tightness, flush, replace fittings, etc.)
Before installing the boiler, the installer is obliged to carry out such activities and issue a written
confirmation of the correct installation and assembly of the boiler, which is a condition of the boiler
warranty. Connecting the boiler to the central heating system should be made by a company with
appropriate authorizations, and the fact of correct connection should be confirmed in the indicated
place on the warranty card attached to this manual. Examples of open-loop system protection schemes,
according to PN 91/B-02413 are presented in Fig. 1a, 1b, 1c. Table 1 below presents the nominal and
external diameters of safety and expansion pipes, depending on the heat output of the central heating
boiler.
Table no. 1
Size of pipes protecting the boiler in open-loop system according to PN-91/B-02413
Thermal power of the boiler [hW]
Safety pipe [mm]
Expansion pipe [mm]
from
to
Ø nominal
Ø internal
Ø nominal
Ø internal
0
40
25
27,5
25
27,2
40
85
32
35,9
85
140
40
41,8

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Option 1 –top diagram
boiler
Option 2 –bottom diagram
boiler
Figure 1a
Location of the expansion vessel above the highest point of the water circulation according to
PN-91/B-02413
The L and H distances are given as standard

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Figure 1b
Scheme of the protection of the water heating system equipped in one boiler or heat exchanger, top
view, pump mounted on the return according to PN91/B-02413.
Figure 1c
Scheme of the protection of the water heating system equipped in two or more boilers or heat
exchangers, pump mounted on the return according to PN-91/B-02413.

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7.5. Protecting boiler in closed-loop system
The most important requirements for DuoKo boilers protected in a closed-loop system with an
expansion vessel. In accordance with applicable regulations, DuoKo-type boilers meet the
requirements of EU directives at the design and production stage. When it comes to the operation, they
are subject to UDT conditions. In accordance with the ordinance of the Ministry of Economy, PiPS of
July 9, 2003, Journal of Laws No. 135 item 1269 boilers of this type are subject to simplified or
limited technical supervision. For boilers with power above 70kW before commencing operation, the
user is obliged to report to the appropriate technical inspection unit in order to obtain a decision
approving the device for operation. Boiler equipment and accessories have a product and the
Operation and Maintenance Manual declarations of conformity as well as operating instructions,
which are an integral part of this Operation and Maintenance Manual. Such requirements must also be
met by the equipment components of the installation and, above all, thermal protection, safety valve
and, expansion vessel.
WARNING!
The use of accessories and fittings of unknown origin is not allowed.
7.5.1. Protection of boiler
Protection of low-temperature water-based boilers for solid fuels with thermal power of up to 300kW
from the use of closed-loop systems with expansion vessels should meet the requirements specified in
PN-EN 12828. Heating systems in buildings. Designing water-based central heating systems.
NOTE!
PN-B-02414: 1999. Protection of closed-loop water heating systems with expansion vessels in case of
applying point 1.1 does not include solid fuel boilers. Therefore, the boiler manufacturer recommends
using PN-EN 12828.
7.5.2. Cooling coil
The cooling coil can be made in the internal system permanently mounted in the boiler water jacket or
in the external system, mounted on the supply nozzle of the boiler.
WARNING!
For DuoKo boilers, the manufacturer is recommending the use of an external cooling system.
The coil used can be made of copper pipe or other special corrugated, ribbed pipes. Cooling coils are
chosen individually for each boiler power ensuring cooling of the boiler water supply in emergency
situations. The external coil is placed in a housing with connectors/nozzles for assembly, as an
additional device of the boiler supply system and installation. It also has a cooling water inlet and
outlet connectors/nozzles and a sensor connector/nozzle.
7.5.3. Blowoff-drain and filling valve
Thermal protection through the use of a blowoff/drain -filling (cooling) valve is used to reduce the
boiler temperature in closed-loop heating systems that do not have a built-in internal or external
cooling exchanger. It consists of a check valve, pressure reducer, filling and discharge valve thermally
controlled by a capillary temperature sensor.
Its task is to directly supply cold water to the boiler water system and the simultaneous outflow of hot
water from the boiler.
The water flow through the cooled boiler should be correctly chosen according to the cooling
parameters in Table 3. It cannot be too low, but it cannot be too intense. The cooling valve is an

17
integrated connection between reducing, filling, and blowoff valves. The filler valve connector/nozzle
should be connected to the mains water source and the boiler return connector/nozzle, while the
blowoff valve connector/nozzle should be connected to the boiler's supply connector/nozzle and
drainage pipe. It is recommended to use an additional cooling system for hot water outflow from the
boiler. The recommended optimal flow of cooling water through the valve is specified in Table 3.
WARNING!
The quick cooling of the boiler can lead to its damage. Use appropriate pressure reducers for the
cooling water supply to the boiler.
7.5.4. Requirement regarding assembly
The boiler has basic mounting connectors/nozzles and sleeves (supply and return, temperature
controller, STB, thermomanometer) and additional couplings to connect the automatic vent and
thermal protection sensor.
After positioning the boiler and connecting it to the chimney, additional equipment required for
protection in a closed-loop system should be installed on the boiler according to PN-EN 303-5: 2012,
PN-EN 12828. To do so, follow these steps:
- for the boiler control system equipped with a cooling device, use: temperature controller, safety
temperature limiter with a manual return to the initial position - STB. This is a standard requirement
for all types of boilers.
- a safety valve provided by the manufacturer should be installed directly on the boiler.
7.5.5. Safety requirements
- it is forbidden to install shut-off valves as well as other devices and accessories on the pipelines
connecting the cooling device with the cooling water inflow and outflow.
- thermal protection devices should be installed near the boiler directly to the supply and return
connections/nozzles.
- drainage from the cooling devices and safety valve should be connected in a safe way to the
sewage system in compliance with the applicable requirements and regulations.
- operation of the boiler without a safety valve or an incorrect and inefficient safety valve is not
allowed, as it may cause failure and risk be hazardous to life or health of people and property. The
requirements specified in the installation and operating instructions for the safety valve must be
strictly observed.
- for boilers in closed-loop systems, the requirements of PN-EN 12828 and other applicable
standards should be applied.
The boiler must be installed in accordance with the above-mentioned requirements and applicable
regulations by an authorized installation company, and the boiler must be commissioned by a trained
service of the manufacturer. Any interference or manipulation with the boiler protection and control
system or connection of additional control devices not included in this manual may result in danger
and void the warranty. Repairs works on the boiler can only be carried out by an installation and
service company trained by the manufacturer. The assembly should take into account the guidelines
and requirements contained in the Operation and Maintenance Manual of cooling devices, expansion
vessels, thermostatic valves, safety devices, and other equipment of a boiler and system.
Responsibility for the correct installation and repair of the boiler is on the installation and service
company, which conducts the first start-up of the boiler and writes it down in the boiler warranty card.
The condition for maintaining the boiler warranty is sending an annotation to the address provided by
the manufacturer.
WARNING!
If the above-mentioned requirements and other safety conditions are not met, then the manufacturer
shall not be liable for accidents and possible consequential damages.

18
WARNING!
It is not recommended to connect the hydrophore water intake.
Table no. 2
List of thermo-technical parameters of cooling valves for DuoKo boilers
Boiler power
Qk
[kW]
19
25
38
50
62
75
100
120
150
200
250
300
Coil power
Qw
[kW]
(0,35 ÷ 0,4) Qk
(0,4 ÷ 0,5) x Qk
Initial water
temperature
Twp
[°C]
10
Final water
temperature
Twk
[°C]
30
Water flow
in coil
Mw
[kg/s]
0,092
0,117
0,186
0,222
0,261
0,364
0,587
0,587
0,866
0,954
1,158
1,390
[I/min]
5,5
7,0
11,1
13,3
15,7
21,9
35,2
35,2
52,0
57,2
69,5
83,4
Boiler power, Coil power, Initial water temperature, Final water temperature, Water flow in coil
WARNING!
The size of the cooling coil was determined in relation to the nominal power of the boiler:
35% ÷ 40% for 19 kW ÷ 75 kW boilers
40% ÷ 50% for 100 kW ÷ 300 kW boilers
For each coil used in the boiler, the given temperature and water flow values should be provided in
order to obtain the required coil thermal power.
WARNING!
The boiler manufacturer recommends the use of "Thermal protection SYR 5067" or appropriate
substitutes with the above mentioned parameters
Table no. 3
List of thermo-technical parameters of cooling valves for DuoKo boilers
Boiler power
Qk
[kW]
19
25
38
50
62
75
100
120
150
200
250
300
Temperature
drop in boiler
∆Tw
[°C]
10
Cooling time
ts
[min]
5
Cooling speed
ws
[°C/min]
2
Cooling water
speed
Mws
[I/min]
0,16
0,21
0,24
0,29
0,34
0,43
0,69
0,69
1,01
1,11
1,32
1,62
2,70
3,43
4,07
4,86
5,71
7,10
11,43
11,43
16,86
18,57
22,00
27,00
Cooling time
ts
[min]
7
Cooling speed
ws
[°C/min]
1,5
Cooling water
speed
Mws
[I/min]
0,12
0,15
0,18
0,22
0,26
0,32
0,51
0,51
0,76
0,84
0,99
1,22
2,02
2,57
3,05
3,64
4,29
5,32
8,57
8,57
12,64
13,93
16,50
20,25
Cooling time
ts
[min]
10
Cooling speed
ws
[°C/min]
1
Cooling water
speed
Mws
[I/min]
0,08
0,10
0,12
0,15
0,17
0,21
0,34
0,34
0,51
0,56
0,66
0,81
1,33
1,67
2,00
2,50
2,83
3,50
5,67
5,67
8,50
9,33
11,00
13,50
Recommended
values

19
7.5.7. Installation scheme
NS- cooling vessel
ZO –cutoff valve
ZB –safety valve
IG –heating system
NP.- expansion vessel
PO –circulation pump
ZT –thermostatic valve
Rys. 1. Schemat montażu kotła w
układzie zamkniętym z
zabezpieczającym wymiennikiem
ciepła - naczynie schładzające z
wężownicą zamontowanym na
zewnątrz.
Fig 2. Installation scheme of the boiler in a closed-loop system protected by a cooling valve..
ZS- cooling valve ZB –safety valve
ZR- reducing valve IG –heating system
ZN- filling valve NP- expansion vessel
ZU- blowoff valve PO –circulation pump
ZO –cutoff valve CT- temperature sensor
IG
PO
ZO
ZB
NP
NS
ZZ
ZT

20
7.5.8. Requirements for closed-loop system operation
Before commissioning, the manufacturer's or trained installer's service must check if all devices and
equipment in a closed-loop system with an expansion vessel are working as they should. The check
must be made by calling the simulated emergency condition in a controlled and safe manner.
WARNING!
During operation, the user is obliged to:
- control of measuring instruments indications (manometer, thermometer),
- gradual checking of the technical condition of safety devices and control of the operation of the
boiler protection system devices - safety valve, thermostatic valve, cooling water flow,
- checking the tightness of the cooling system - any leakage of the heat exchanger causes a pressure
drop in the system and outflow of boiler water from the cooling water outlet connector/nozzle during
normal operation,
- a comprehensive check must be done before the start of the heating season and successively, every
1-2 months.
WARNING!
At least once during the heating season, it is recommended to carry out inspections and checks by the
manufacturer's service or an authorized installation company.Systematic inspections are a prerequisite
for the proper operation of safety devices and for safe work and safe operation of the boiler.
7.5.9. Guidelines for t choosing expansion vessels (closed-loop systems) according to PN-EN
12828: 2003 –attachment D
D.1 General provisions
The following guidelines are recommended when using expansion vessels:
a) The location of the expansion vessels in the central heating system defines the neutral point in the
system. In this place, the static or total pressure is always constant, regardless of the operation of the
circulation pumps. This location should be chosen so that the pressure of the suction circulation pumps
will be sufficient for their operation, that is, protecting against cavitation and maintaining the
temperature load of the expansion vessel at a minimum level. The filling point should be between the
connection point of the expansion vessel and the inlet to the circulation pump. The recommended
connection point for the expansion vessel to the system is shown in Figure D.1;
b) Maximum temperature, including the design temperature being exceeded. A defect in the safety
thermostat may cause the temperature to rise above the highest operating temperature to a higher
temperature, defined as the maximum temperature, taking into account the design temperature
exceeding θmax. This maximum temperature in a central heating system that occurs during a failure
should be used to calculate the size of the vessel;
c) Initial design pressure in the system. Initial design system pressure, pO, should be at least the sum
of static pressure, pST, and steam pressure, pD:
p0 ≥ pST + pD
The minimum p0 value should be 0.7 bar. The surplus calculated based on practice and added to the
static pressure instead of the water vapor pressure is 0.3 bar;
d) Final design pressure in the system. Final design pressure in the system, pC should not be higher
than the pressure set on the safety valve reduced by the pressure difference at closing and opening
(usually 10% of the pressure set on the safety valve);
e) The difference in static pressure between the position of the expansion vessel and the safety valve
should be taken into account;
f) The total system capacity, Vsystem should be determined. In the event that it is not possible to make
accurate calculations, excess/surplus of safety should be used to estimate the capacity;
g) The minimum capacity of the expansion vessel, Vsystem should be determined. The method for
choosing the exact capacity is provided in D.2 should be used. If the design data are not complete,