Important!
This operating manual contains important information for the operator. The
boiler must be professionally installed and operated in order to avoid potential
accidents.
Familiarize yourself with the contents of this manual before installing and
operating the boiler.
Be sure to also comply with the regional regulatory provisions; they may differ
in full or in part from the requirements named in this manual. In this case, the
regulator requirements always have precedence! The master chimney sweep
responsible for your region can always provide information.
The company KÜNZEL would like to thank you for your trust!
Contents
1 Installation manual pellet boiler 4
1.1 Usage in compliance with statutory regulations ...................... 4
1.2 The key controls and components ............................. 4
1.3 Installation ......................................... 5
1.3.1 The boiler room ................................... 5
1.3.2 Transportation of boiler .............................. 6
1.4 Installation of the burner .................................. 6
1.5 Installation of the burner hood ............................... 7
1.6 Operate cleaning lever (only PK 10 and PK 20) ...................... 8
1.7 Chimney connection .................................... 9
1.8 Heating connection ..................................... 9
1.8.1 General ....................................... 9
1.9 Electrical supply connection ................................ 10
1.9.1 General ....................................... 10
1.9.2 Boiler and burner ................................. 11
1.9.3 Boiler sensors .................................... 11
2 Installation instructions for external pellet filling system 12
2.1 External conveyor screw .................................. 12
2.1.1 Rigid conveyor screw from the silo built by the building contractor ........ 12
2.1.2 Flexible conveyor screw from pellet storage room ................. 15
2.1.3 Flexible conveyor screw from bag silo ....................... 16
2.1.4 Storage tank with rigid conveyor screw ...................... 17
3 System proposals for the pellet boiler 18
3.1 PK2 system package - pellet boiler with domestic water heater and buffer tank . . . . . 18
3.2 PK3 system package - pellet boiler with combi-buffer tank ................ 20
3.3 PK4 system package - pellet boiler with solar-suppl. heating and domestic hot water . . . 22
3.4 PK5 system package - pellet boiler with solar-supplemented heating ........... 23
3.5 Legend for the system packages .............................. 24
4 Technical data 25
4.1 Wiring diagrams ...................................... 27
Cover image: Rigid conveyor screw from the silo built by the building contractor
3
1 Installation manual pellet boiler
1.1 Usage in compliance with statutory regulations
This pellet boiler is approved for the operation of an open or closed circuit hot water heating system with
a permissible operating pressure of up to 3 bar and a maximum flow line temperature of 95◦C.
It is not permitted to operate the pellet boiler without a return flow booster. The operation of the return
flow booster is to be monitored. A 4-way mixing valve is sufficient as a return flow booster on systems
with a buffer tank.
The boilers supplied by KÜNZEL are stationary units that comply with the WEEE Directive. The elec-
trical and electronic components contained in the boilers do not fall within the remit of this directive and
will therefore not be taken back by KÜNZEL. Please take these components to the recycling depot.
We do not assume any liability for any malfunctions resulting from the use of non-genuine KÜNZEL
components. This particularly applies to control units, external materials handling equipment and fuel
pipes from other manufacturers. We also do not assume any liability for operational difficulties resulting
from inadequate hydraulic and/or exhaust gas systems.
We reserve the right to make technical changes.
1.2 The key controls and components
Figure 1: The key controls and components
1 Boiler thermometer 11 plugged connectors for boiler sensors, serial interface
2 boiler thermostats 12 Igniter safety device
3 Temperature safety limiter 13 Burner quick release lock
4 Mains power switch 14 Burner door
5 Fullness sensor 15 Flame deflector
6 Filling spout 16 Ash pan
4
7 Burner control unit 17 Burner door catch
8 Main burner fuse 18 Door contact switch
9 Connection cable for conveyor screw 19 Type identification plate
10 Connection cable burner
1.3 Installation
•Before installing the pellet boiler approval must be obtained from the responsible master chimney
sweep.
•A flue gas system must be available that is approved for the operation of the pellet boiler.
•Please check whether planning permission is required.
•The boiler may only be installed by an approved heating specialist.
•When installing the boiler, ensure that all combustible or temperature-sensitive materials (cables,
insulation) are kept at least 40 cm away from the exhaust gas duct and 20 cm away from the boiler
shell.
•No combustible materials are permitted to be directly beside, above or in front of the boiler or the
filling hose. They must always be kept a minimum of 40 cm away.
•The boiler installation (heating system, electrical supply, safety equipment) must be state of the
art.
•If the heating system is operated with a flow line temperature of more than 100◦C , the boiler
plant must be reported to the responsible trade supervisory centre in accordance with the German
Ordinance on Steam Boilers.
•The relevant standards and building authority regulations must be complied with. Among other
regulations, the following apply: the German Fire Code (FeuVo), the Federal Immission Control
Ordinance (BImSchV.), the VDE guidelines, EN 303-5 and to the heating system DIN 4751.
1.3.1 The boiler room
The pellet boiler may only be installed and the pellets stored in a dry, frost-proof room that isapproved for
the installation of boilers and the storage of fuels. The building contractor is to ensure that the installation
space is sufficiently ventilated.
A level, sufficiently strong floor manufactured from non-combustible material is adequate for the
installation of the pellet boiler. Should a foundation pedestal be used, this is to be made at least as
large as the dimensions of the boiler. The installation must also comply with the local regulations and
guidelines applicable to boiler room installations.
The boiler installation should already take account of the subsequent position of the materials handling
system!
5
Figure 2: Minimum offset dimensions for installation (view from above)
1.3.2 Transportation of boiler
As a result of its compact design, it is possible to bring the pellet boiler through a 750 mm door opening
into the installation space. In order to make the boiler casing easier to carry, carry bushings have been
fitted to the boiler, into which 1 inch pipe ends can be screwed.
•On the PK 15, these are located to the right and left below the covering caps.
•On the PK 10 and PK 20, the carry bushings are located at the front below the slanted cover panel
and beneath covering caps.
Once the installation has been completed, it should be ensured that the turbo gratings are correctly seated.
Illustrations on this subject can be found in the operating manual for the pellet boiler in the section
entitled "Maintenance and care" / "flue gas ducts".
1.4 Installation of the burner
Figure 3: Lock open Figure 4: Lock closed
The burner is secured in position using quick-release locks fitted to the burner door. When installing the
burner, proceed as follows:
6
•Remove the flame deflector from the burner shell. Important: The burner may only be installed or
removed without the deflector, otherwise the door insulation may be damaged.
•Now slide the burner into the burner hole in the burner door.
•Now set the two locks so that the burner is seated firmly in front of the burner door and the burner
contact switch is actuated. The burner is only permitted to have a very modest amount of play.
•As the burner seal beds in it is necessary to check the locks once again after about 4 weeks and
adjust them if required.
•Now re-install the flame deflector in the burner.
Only PK15:
At last the red hood has to be slid onto the burner fitting the rear metal sheet of the hood between washer
and clip (see pic. below).
Figure 5: Sliding on the hood
1.5 Installation of the burner hood
The pellet burner is supplied with the hood mounted. For maintenance or cleaning purposes, it can be
necessary to remove the hood. Before starting to do this, disconnect the burner completely from the
mains power supply. When removing the hood, proceed as follows:
•Remove the discharge chute cover. This requires the use of a T10 torx bit.
•Release the fastening screw holding the control module and lift it carefully upwards out of its
seating.
•Release the screwed fastenings holding the hood.
•Withdraw the hood rearwards
Use this procedure in reverse to install the hood. Only the torx screws provided may be used for the
installation of the hood. Please note: The burner may not be operated without a properly installed
hood. There is otherwise a risk of injury and the danger of electrical shocks !
7
Figure 6: The burner hood
1.6 Operate cleaning lever (only PK 10 and PK 20)
As standard, the lever for the manual register cleaning mechanism is located on the right hand side of
the boiler (in the case of PK 15 on left hand side). Yet, sometimes it can be more sensible to move the
cleaning lever to the left hand side of the boiler, although it is only possible to do this on PK 10 and PK
20 boilers.
Figure 7: The cleaning lever
•Remove the red panel cover from the boiler and open the register cover located below it with an
Allen key.
•Release the screws marked with an arrow in the illustration and withdraw the shaft and handle
from the boiler in a rightward direction.
•Remove the black collar from the housing.
8
•Open the pre-cut hole on the left hand side of the boiler and re-insert the collar in this hole.
•Now slide the shaft from the left into the boiler; ensure it is positioned correctly (underneath the
follower lever, see figure!)
•Bolt the shaft and the follower lever back together.
1.7 Chimney connection
The KÜNZEL pellet boiler is fitted with a forced draft fan. In order to ensure safe operation of the pellet
boiler, it is necessary to ensure that the flue gas branch of the pellet boiler has a negative pressure of at
least 10 Pa under all operating conditions. However, this negative pressure may not exceed 18 Pa under
any operating conditions. KÜNZEL recommends the use of a draft regulating device. When putting the
unit into service for the first time, the draft is to be measured and recorded when the unit is cold and
when it is operating at its maximum output setting.
The exhaust gas duct to the chimney should be as short as possible, without any bends and installed at
a slight incline. The connection to the chimney should have an aerodynamic design that curves upward.
The connector joining the furnace and the chimney must comply with EN 1856-2:2004 and have the
required identification marking (CE). In accordance with EN 1856-2:2004, non-insulated connectors
must be kept at least 40cm cm away from combustible components. We recommend the use of insulated
connectors.
The figures required for the chimney design calculations can be found in the technical data listed in
section 4on page 25. Calculated chimney diameters that are smaller than the flue gas branch of the boiler
are not permissible.
Important: Please note that the low exhaust temperatures occurring during prolonged operation may
mean that it is necessary to fit a moisture-resistant chimney (thermal conductivity factor - resistance
group I in accordance with DIN 18160/T1).
Before connecting the pellet boiler to an existing chimney, subject it to a chimney calculation or obtain
a chimney report. Before commencing with the installation it is essential to obtain the approval of your
local master chimney sweep.
It is essential to ensure that the flue gas duct is airtight. Exhaust gases could otherwise leak into the boiler
room under some circumstances. This applies in particular to the cleaning hatches on the duct elbows.
1.8 Heating connection
1.8.1 General
The PK type pellet boiler are designed for use with open or closed-circuit heating systems with a maxi-
mum operating pressure of 3 bar and a maximum flow line temperature of 95◦C.
The following safety equipment is to be installed by the building contractor:
•A pressurised expansion tank (please take account of any buffer tanks fitted to the system)
•A safety valve with a maximum actuation pressure of 3 bar at the highest point of the heat generator
•A thermometer and a manometer
9
Figure 8: The chimney connection
Please note: Only products whose components have been tested may be employed
We recommend designing the heating system in line with the example system detailed in section 3 on
page 25. KÜNZEL absolutely recommends the use of a buffer tank with a capacity of at least 500 l.
. Using a buffer tank ensures that the boiler can operate with extended burner operation times even
when the heat consumption of the heating system is either low or fluctuating markedly. This leads to
a significant reduction in emissions, as well as wear and tear and soiling of the burner and igniter element.
In order to prevent the pellet boiler from corroding, the boiler is operated with an elevated minimum
temperature. This is 50◦C for systems without a buffer tank, and 60◦C for systems with a buffer tank.
For this reason, a separate return flow temperature booster has to be fitted, e.g., the Thermomix valve
(Part. No. 150218) from KÜNZEL.
Due to the elevated minimum temperatures, the heating system must always be equipped with an au-
tomatic mixing valve. 3-way mixing valves are to be fitted to systems with buffer tanks. 4 way mixing
valves are to be fitted to systems without a buffer tank.
1.9 Electrical supply connection
1.9.1 General
•The electrical supply must be connected by an approved electrician.
•A residual current circuit breaker is to be fitted.
•The electrical supply connection for the boiler is to be protected by a max. 10 A fuse.
10
1.9.2 Boiler and burner
The mains power supply for the boiler, burner and conveyor screw is routed via the mains power cable
to the rear panel of the boiler (white plugged connector) and can be disconnected using the mains power
switch on the boiler control panel.
Figure 9: Plugged connectors on the rear panel of the boiler
The burner thermostat control circuit (green plugged connector) serves to connect the differential tem-
perature control unit (Thermomat) or another control system.
A circuit diagram can be found in the appendix.
1.9.3 Boiler sensors
The sensors for the boiler thermostat and the temperature safety limiter are already installed beneath the
cover panelling.
The boiler sensor for the differential temperature control unit must be inserted into a vacant immersion
sleeve beneath the cover (see fig.). On the PK 15, the immersion sleeves are below the panelling with
the control panel. These must be removed previously. The screws can be accessed from the rear.
The sensor should be positioned in the immersion sleeve so that it can be easily pressed against the wall
of the sleeve. Sensors that are loose in immersion sleeve have poor heat transfer characteristics and could
lead to switching errors. In order to improve the switching accuracy, we recommend filling the immersion
sleeve with heat conductive paste
11
Figure 10: Position of the immersion sleeve below the cover
2 Installation instructions for external pellet filling system
We offer various silo and materials handling systems for installation in pellet storage rooms or bag silos
set up by the building contractor.
You can find information about the design of the pellet storage room in our pellet design folder or relevant
literature. An impact mat is to be fitted. Chipped off parts of the wall or plaster can fall into the pellet
feed chute and cause damage to the burner that is not covered by the guarantee! In addition, the intake of
dust is detrimental to the combustion process and can lead to increased slagging in the burner.
2.1 External conveyor screw
2.1.1 Rigid conveyor screw from the silo built by the building contractor
This 3 metre long conveyor screw is supplied with a 240 V motor and is part of the product contents for
the PK pellet boiler. The conveyor screw is controlled directly by the pellet burner.
In order for the pellet feed system to function perfectly, it is very important that certain angles, shown in
the following figures, are observed.
The external conveyor screw is suspended from the ceiling of the installation space using the supplied
tensioning hook. Ensure the ceiling is sufficiently strong to bear the load before starting the installation
procedure. The equipment must be fastened using suitable means.
12
Figure 11: The suspension arrangement
If the ceiling is not sufficiently strong, a suspension frame (part no.: 100053) is available as an optional
accessory.
Fasten the downpipe hose to the output of the external conveyor screw and the input of the burner using
hose clamps; apply some washing-up liquid to the internal surface of the hose if necessary to simplify
the installation procedure. Stretch the hose so that it is not possible for any pellets to become trapped
within it. Otherwise the hose could become blocked and necessitate repair work. However, please note
that the hose must be long enough to allow the burner door to swing open.
In order to ensure that the external pellet silo is emptied as well as possible, position the input to the
external conveyor screw in the centre and/or at the lowest point of the external silo. Please note that a
storage room can never be emptied entirely because the pellets generally have an angle of repose of
about 45◦(in the case of flour it can be as much as 80◦). The amount of remaining material depends on
the design of the storage room and can only be used if it is moved so that the pellets can be captured
by the conveyor screw once again. Providing the walls with inclined smooth surfaces improves the
emptying of the silo.
13
Figure 12: Correct installation of the conveyor screw
The rigid 3 metre long conveyor screw can be shortened to any length required, as long as its inclination
is kept to between 30◦and 50◦(see fig.). The pipe end must then be cut to 30◦again. The conveyor screw
may not protrude from the pipe.
Figure 13: Outlet angle of the rigid conveyor screw
The size of the hole in the wall depends on the wall thickness and the suspension angle. For example,
a suspension angle of 50◦and a wall thickness of 10 cm would require a hole height of 26 cm (wall
thickness [cm] * tan50◦+ 14 cm), the width remains unchanged at roughly 10 cm.
Please note: Do not touch the conveyor screw when the drive motor is connected. There is a risk of
injury!
14
2.1.2 Flexible conveyor screw from pellet storage room
The conveyor screw is controlled by the burner control unit. The building contractor is to provide a
3-phase 400 Volt 3 x 16 ampere electrical supply connection that is in turn controlled via the motor
connection set relay (part no.: 100052).
Figure 14: Flexible conveyor screw from the storage room
The length of the conveyor screw is not permitted to exceed 25 metres. Two conveyor screws with a
transfer device are to be used if a greater distance has to be bridged. The minimum installation radius
for the conveyor screw is 1.5 metres. All of the curves followed by a conveyor screw must together have
an angle of not more than 135◦. The maximum angle than can be achieved in one bend is 90◦. After
this only one bend with an angle of not more than maximal 45◦is permissible, but this must be in the
opposite direction to the first bend.
Figure 15: External conveyor screw
The number of inlet funnels required varies according to the dimensions of the pellet storage room.
Please note that a storage room can never be emptied entirely because the pellets generally have an angle
15
of repose of about 45◦(in the case of flour it can be as much as 80◦). The amount of remaining material
depends on the design of the storage room, and can only be used if it is moved so that the pellets can be
caught by the inlet funnels once again.
The first inlet funnel must be located at least 600 mm away from the wall. The other funnels are then
positioned at a distance of not less than 600 mm and not more than 1000 mm.
The following set-up is suitable for a pellet storage room with a length of 2.5 m.
1. 1 Stk. conveyor screw 5.5m
2. 1 Stk. pipe bend 45◦
3. 1 Stk. pipe 2.5m
4. 1 Stk. pipe 1.8m
5. 3 Stk. inlet funnels
6. 1 Stk. motor (0,37kW; 400 volt, 3x16 ampere) with flange and motor mounting
7. 1 Stk. connection hose
8. 1 Stk. motor connection set (electrical contactor and motor circuit breaker)
9. 1 Stk. various minor components
Further accessories for the storage room:
1. Filling connection kit (part no.: 100065) consisting of 2 x Storz connections type ALU, 2 x blind
cover incl. fittings.
2. Filling and air bleeding connections 50 mm (part no.: 100060), 200 mm (part no.: 100061), 500
mm (part no.: 100062), 500 mm with earthing clamp (part no.: 100067), 1000 mm with earthing
clamp (part no.: 100063)
3. Bend for filling and air bleeding line 5◦(part no.: 100070), 15◦(part no.: 100071), 30◦(part no.:
100072), 45◦(part no.: 100073), 60◦(part no.: 100074), 90◦(part no.: 100075)
4. Z-bend for storage room(part no.: 100018) consisting of 2 x Z-bend each 2 m in length
5. Impact mat (part no.: 100017) consisting of plastic impact mat - 1.50 m x 1.50m.
2.1.3 Flexible conveyor screw from bag silo
The conveyor screw is controlled by the boiler control system. The building contractor is to provide a
3-phase 400 Volt 3 x 16 ampere electrical supply connection that is in turn controlled via the motor
connection set relay (part no.: 100052).
16
Figure 16: Flexible conveyor screw from bag silo
Further design of the conveyor screw is not required. The unit is installed directly onto the outlet of the
bag silo using the installation instructions provided with the silo system.
2.1.4 Storage tank with rigid conveyor screw
Figure 17: Storage tank with rigid conveyor screw
17
3 System proposals for the pellet boiler
3.1 PK2 system package - pellet boiler with domestic water heater and buffer tank
The system proposal in accordance with the PK2 system package permits the construction of a straight-
forward, economical and space-saving pellet heating system with a regulated domestic hot water tank
and buffer tank. A 4-way mixing valve is not sufficient to serve as a return flow booster for this system.
For this reason the Thermomix valve must be fitted.
Ensure that the boiler circulation pump (15) and the heating pump (18) are correctly matched to one
another.
We recommend installing the Thermomix valve and the buffer tank so that they can be completely iso-
lated in order to simplify maintenance work.
Please read the operating and installation manuals for all of the units before installing the system. The
electrical installation for the system may only performed by a qualified electrician. The use of PVC-
insulated cables is not permitted in the boiler.
Hydraulic diagram
Figure 18: PK2 system package
18
Figure 21: Wiring diagram for PK2 system package
3.2 PK3 system package - pellet boiler with combi-buffer tank
The system proposal in accordance with the PK3 system package permits the construction of a straight-
forward, economical and space-saving pellet heating system with a combi-buffer tank and an unregulated
domestic water heater. A 4-way mixing valve is not sufficient to serve as a return flow booster for this
system. For this reason the Thermomix valve must be fitted. In particular, this system design is also suit-
able for the construction of a solar heating system that is intended to supplement a conventional heating
system.
Ensure that the boiler circulation pump (15) and the heating pump (18) are correctly matched to one
another.
We recommend installing the Thermomix valve and the buffer tank so that they can be completely iso-
lated in order to simplify maintenance work.
Please read the operating and installation manuals for all of the units before installing the system. The
electrical installation for the system may only performed by a qualified electrician. The use of PVC-
insulated cables is not permitted in the boiler.
When installing the combi-buffer tank, remember to check the state of the protective anode in the storage
heater; a defective anode can unnecessarily reduce the service lifetime of the boiler. We recommend
checking the anode at least once a year.
Hydraulic diagram
20
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