pellets boiler - Paul Künzel GmbH & Co.

Operating and Assembly Manual
for the
KÜNZEL
Pellet Boiler
Type PL15 and PL25
Paul Künzel GmbH
Co.
Ohlrattweg 5
25497 Prisdorf
13. September 2006
1

Inhaltsverzeichnis
1 Operating Instructions for the Pellet Boiler 4
1.1 Delivery ........................................... 4
1.2 Accessories ......................................... 4
1.3 Installation Directions .................................... 4
1.4 Assembly .......................................... 5
1.5 The Boiler Back–End Protection .............................. 5
1.6 The Identification Plate ................................... 5
1.7 Setting Up .......................................... 5
1.8 Separating the Boiler from the Integrated Pellet Bin .................... 6
1.9 Chimney Connection .................................... 7
1.10 Heating Connection ..................................... 7
1.11 Assembly of the Ventilator ................................. 8
1.12 Assembly of the Control Panel ............................... 9
1.13 Electric Heating Cartridge ................................. 10
1.14 External Feeding of the Pellets ............................... 11
1.15 Fixing the Pellet Storage Bin ................................ 12
1.16 PL 25 ............................................ 12
1.17 Operation .......................................... 13
1.17.1 Operation without Heating Electronics ....................... 15
1.17.2 Operation with Heating Electronics ........................ 15
1.17.3 Operation with Buffer Storage ........................... 16
1.18 Maintenance and Service .................................. 16
1.18.1 Monthly Cleaning ................................. 17
1.18.2 Additional Half–Yearly Cleaning ......................... 21
1.18.3 Ventilator ...................................... 23
2 The KUENZEL Thermomix Valve 24
2.1 Legend to the Plans ..................................... 26
3 System Suggestions for the PL 27
3.1 Package PL1 for Pellet Boilers with Hot Water Tank .................... 27
3.1.1 Hydraulic–Plan ................................... 27
3.1.2 Electro–Plan .................................... 28
3.2 Package PL2 for Pellet Boilers with Hot Water Tank and Buffer Storage ......... 28
3.2.1 Hydraulic–Plan ................................... 29
3.2.2 Electro–Plan .................................... 29
3.3 Package PL3 for Pellet Boilers with a Combi–Tank .................... 29
3.3.1 Hydraulic–Plan ................................... 30
3.3.2 Electro–Plan .................................... 30
4 Connection Box for the Heating Electronics Type Theta 31
4.1 Assembly .......................................... 31
3

1 Operating Instructions for the Pellet Boiler
1.1 Delivery
The KUENZEL Pellet Boiler is sealed in environmentally–friendly PE foil and is delivered on disposable
pallets with an enclosed control panel and ventilator.
1.2 Accessories
Enclosed with the pellet boiler are:
1 guarantee card
1 cleaning brush
15 kg pellets
1.3 Installation Directions
This pellet boiler has been approved for operation with an open or closed heating system with an allowed
operational pressure of a maximum 3 bar and a maximum flow temperature of 95◦ C.
The pellet boiler must not be operated without the boiler back end protection. The function of the boiler
back–end protection should be supervised. With systems without a buffer storage, a 4–way mixer is
sufficient as the boiler back–end protection.
This pellet boiler must only be operated with fuel according to the German norm BImSchV figure 5a
(using wooden pellets made of natural untreated wood). (This boiler corresponds to the German official
acts for operating boilers as well as to the DIN EN 303–5). (DIN stands for Deutsche Industrie Norm
which means the German Industry Norm)
Only pellets with a diameter of 6mm or 8mm are permitted. The pellets must correspond to the standard
of the DIN Plus or of the PVA (Pellets Association Austria). Other fuels, especially pellets which contain
recycled material, must not be used.
Please be aware that the DIN 51731 pellets can have a higher proportion of ash and a minor non–
abrasiveness than the PVA or DIN Plus pellets. The minor non–abrasiveness can cause a considerably
high proportion of dust which may lead to failure of the screw conveyor. DIN 51731 pellets are, as a rule,
not suitable for operation in the pellet boiler due to their bad material properties.
The details of the cleaning schedule refers to the PVA pellets. When other pellets are used, a more
frequent cleaning might be required, as there is a danger of a heavy slag build–up in the burner.
In the interests of operation safety, it is not advisable to put in other fuels than DIN–Plus or PVA–
Standard pellets!
Do not fill the boiler with shavings or dust.
–Danger of explosion–
All KUENZEL products are subject to technical alterations. KUENZEL assumes no liability for functional
problems due to using component parts which are no KUENZEL products. This refers especially to
control devices of other makes. KUENZEL assumes no liability either in case of operating problems due
to on–site conditions like the hydraulic system, exhaust gas system or external conveyor technique.
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1.4 Assembly
The KUENZEL Pellet Boiler is type–examination tested (DIN K 2106/90) and complies with the
BImSchV of Oktober 1988.
Before the pellet boiler is assembled, the approval of the appropriate chimney sweep service must be
obtained. Please check if building permission is required. The assembly of the boiler must only be carried
out by an authorized heating technician. In the same way, the electrical connections must be carried out
by an authorized electrician. An leakage current protection–switch should be supplied. In the boiler,
only heat–resistant silicone cables should be fitted! Do not use PVC cables.
The relevant norms and official building regulations should be complied with.
Advice regarding the assembly and service of the control panel are to be found in the control panel
operation instructions manual.
1.5 The Boiler Back–End Protection
This pellet boiler must only be operated with a boiler back–end protection. In systems without buffer
storage and with little water volume, a 4–way mixer is sufficient. For systems with buffer storage or with
a large water volume, the KUENZEL Thermomix Valve (article no. 150218) is required.
1.6 The Identification Plate
Abbildung 1: Identification plate and factory number
If you have any questions or complaints about your boiler, please always quote the 6–digit factory number.
This number is on the identification plate.
The identification plate is to be found behind the ash door.
1.7 Setting Up
The KUENZEL Pellet Boiler PL is delivered on a transport pallet. Due to its compact shape, it is possible
to bring it into the boiler room through a 750mm wide door opening. Advice: For easier transport, the
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Abbildung 2: Boiler and integrated pellet storage bin are transported separately
integrated pellet storage bin is detachable. In this way, it is also possible to carry the boiler down narrow
cellar steps.
When setting up, the local regulations and guidelines regarding installation in boiler rooms should be
observed.
Setting up the pellet boiler and the pellet storage must only take place in a dry, frost–proof authorized
room. A sufficient ventilation regulation in the boiler room has to be made sure.
For setting up the boiler, a level and adequately load–bearing floor is sufficient. If, however, a pedestal
has to be used, it should be the same size or slightly bigger than the boiler itself.
1.8 Separating the Boiler from the Integrated Pellet Bin
So that the KUENZEL Pellet Boiler can be carried more easily into rooms which are difficult to access,
one can separate the main body of the boiler from the pellet storage bin. This job can only be carried out
by two men.
To separate the integrated pellet bin from the boiler, these guidelines are to be followed:
1. Loosen the pellet supply flange screws as shown in the picture and put them aside.3 auf Seite 7
2. Loosen the screws at the four points of attachment as portrayed in picture ?? auf Seite ?? and put
them aside.
3. Now lower the pellet bin carefully from the flange.
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Abbildung 3: Flange screws in pellet bin
In order to carry the main body of the boiler, there are two points of attachment on the right and left sides
of the boiler into which 1“ pipe ends can be screwed.
Now, the body of the boiler is able to be carried.
1.9 Chimney Connection
The KUENZEL pellet boiler is equipped with an exhaust gas ventilator. The ventilator can be fitted with
the exhaust gas escape which can point optionally to the right, to the left or in an upward direction. An
exhaust gas escape pointing downwards is not permissable.
The exhaust pipe to the chimney should be short, without any extra bends if possible and fixed in an
upward direction. When inserting it into the chimney, it should be rounded off at the top and fitted into a
position which allows the draught current to flow through well.
For any important information regarding the chimney calculations please refer to the technical data in
chapter ?? auf Seite ??. To use a chimney which has a smaller diameter than the smoke ducts is not
permissable.
Caution: Please be aware that with the low exhaust temperatures occuring constantly whilst in operation,
a damp–resistant fireplace (heat–flow number and resistance group I of the type DIN 18160/T1) may be
required.
If the boiler has to be connected to an already existing chimney, the dimensions of the chimney must
be calculated / a chimney report must be done beforehand. The agreement of your local chimney sweep
service must be obtained before installation.
Due to the ventilator, disruptive noises can occur at the chimney. For this reason, we recommend that the
connection should be made with a flexible exhaust gas pipe input into the chimney.
Make sure that the exhaust gas pipe has been tested to be free of leaks, as otherwise exhaust fumes could
escape into the boiler room. This applies especially to the cleaning openings at the bends in the pipe.
1.10 Heating Connection
In order to avoid operational disruptions, we recommend to you that the heating connection should be
formed according to one of the published KUENZEL system packages. For this, please note chapter3
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auf Seite 27.
Abbildung 4: The 4 places of attachment
The connection of the flow and return must be set up so that they cross each other, in order to avoid a
short–circuit of the current. Caution: When choosing the flow connecting pieces, pay attention to the
fitted position of the ventilator! If the ventilator has been assembled with the exhaust gas escape pointing
to the right, the right flow connecting pieces would be hidden and, therefore, would be unable to be used.
1.11 Assembly of the Ventilator
The ventilator is fitted to the exhaust gas excape nozzle on the rear side of the boiler. Push the ventilator
onto the nozzle. The fan can then be turned so that the exhaust gas escape can be optionally positioned
facing the right, left, the top or bottom.
Now assemble the smoke pipe and adjust the exhaust gas facility. Then the ventilator should be fixed to
the nozzle with the three clamp–screws.
You must make sure that the exhaust gas system is leak–proof, as otherwise under bad conditions
smoke gas could escape!
Make sure that the space where the flue–pipe is, between the ventilator and the chimney, can still be
reached for cleaning purposes.
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1.12 Assembly of the Control Panel
Abbildung 5: Exhaust gas ventilator
Abbildung 6: Assembling control panel
The service instructions of the Control Panel 806 need to be read as they contain the directions for
attaching the screws. If further information about this is required, the screw attachment instructions are
additionally described on the back of the control panel.
Enclosed with the Control Panel 806 are also two buffer sensors (6 metres long) and a boiler sensor,
which are to be found next to an operation instructions manual and a plastic bag with all the necessary
plugs in it. If the boiler is operated on a heating system with buffer storage, the buffer sensors must
be connected. To do this, please pay attention to the guidelines in the control panel manual. If a buffer
storage is not installed, then the connection of the buffer sensors cannot be made.
The boiler sensor should now be inserted into the middle immersion case of the boiler and connected to
the appropriate place on the sensor plug.
The left immersion case is reserved for the boiler sensor of the optional weather–responsive heating
electronics.
The cables for the vacuum sensor, for contact switch of the pellet bin flap and for the exhaust gas sensor
are also connected to the sensor plugs of the 806–control panel. If the heating electronics are inserted, the
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Abbildung 7: Control panel 806 with weather–responsive heating electronics (optional) and safety temperature
limiter
evaluation cable for the burner must be connected additionally to the bottom sensor plug. Details about
this can be found in the connection box manual.
The cables for the ventilator, the electronic fuse and the conveyor screw will have been fitted into the
boiler. The cables for the components which need to be fitted by client, such as those for mains connection
or for the boiler circulation pump, must be fitted into the boiler by a qualified electrician. For this purpose,
there is a little channel for the cables on the left side of the boiler. The cable for the ventilator will have
already been fitted through this channel.
Now insert all plugs into their appropriate places on the control panel.
The control panel should then be pushed into place until it is safely secured on its little pins.
1.13 Electric Heating Cartridge
If requested, the KUENZEL boiler can be equipped with an electric heating cartridge (article no. 150246)
for frost protection. For the connection of this electric heating cartridge, a connection for strong currents
(3x 400 volts 16 amps) should be inserted.
The electric heating cartridge can also be operated with 230volt 25 amps. For this, the wiring of the
cartridge should be changed according to the details of the manufacturer. Caution: These tasks must
only be carried out by a qualified electrician. Please consult the enclosed electric heating cartridge
instructions manual if you want to find out the exact wiring plan.
On the back of the boiler, there is a two inches socket, into which the electric heating cartridge can be
inserted.
The electric heating cartridge has its own thermostats. This thermostat can be adjusted to a variable
temperature between 5oC and 75oC. If the electric heating cartridge only has the function of a frost
guard, it is sufficient to adjust the thermostats by turning the control to the left (5o C).
In order to avoid switching on the electric heating cartridge unintentionally, the contact for the secondary
heating can also be used. The electric heating cartridge cannot be, however, switched on or off directly
by using this. An in–between relay is always required. Important: This also applies to the connection
with 230 volts!
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Abbildung 8: Plan of connections for PL with ext. conveyor screw for 400V motor
1.14 External Feeding of the Pellets
The pellet boiler is equipped with a large integrated pellet storage bin. The pellet bin fill–up by hand
is standard, but the boiler is also optionally equipped with an automatic, external pellet feeding facility.
The control of this external feeding of pellets is done by the Control Panel 806. The following additional
articles will definitely be needed for an external feeding:
Feeder fittings for the pellet storage bin (type no. 100050)
Full–registration for the pellet storage bin (type no. 100051)
Motor connection set for a 400 volt three–phase motor (type no. 100052)
We can offer you different hopper–systems and conveyor screws suitable for solidly built pellet storage
rooms. Further information about this can be found in the boiler planning folder or in our price list.
The external pellet bin feeding of the Control Panel 806 can be started at any given point in time by
the operator (e.g. 15:00). The feeding runs until the bin is full or until the programmed filling up time
has run out. Make a note of how long the feeding facility takes until the bin is completely full i.e. to its
maximum registration. Then adjust the maximum filling time to approx. 5 minutes longer than the actual
filling time.
The filling of the pellet bin is now automatically repeated every 24 hours by the control panel. Depending
on the motor type used, the electrical connection is made according to plan8 auf Seite 11 or according
to plan 9 auf Seite 12.
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Abbildung 9: Plan of connections for PL with ext. conveyor screw for 240V motor
Important: For 400 volt three–phase motors, the KUENZEL motor connection set of the type no.
100052 is recommended. If the motor connection has already been fitted, it is advisable to use the corresponding
motor protection–switch.
Attention: Take care that there evolves no vaccum in the pellet bin when the external pellet storage
is beeing filled. You can avoid this by simply opening the flap of the pellet bin. Before having the external
storage room filled switch off the KUENZEL pellet boiler. To do this, press the START/STOP
button to produce a burn–out and make sure there are no glowing or burning pellets left in the fire
pan or on the ash–tray. Filling up the external storage room must take place under observation
only!
1.15 Fixing the Pellet Storage Bin
For safety reasons, the lid of the pellet bin must always be kept closed during operation . If the flap
opens, the conveyor screw will stop and the caution symbol on the control panel will light up. If the flap
is closed again, the lighted symbol will disappear and operation will resume.
Please always be aware that the the pellet bin lid closes well. If the locking screw is getting loose, it must
be tightened again.
1.16 PL 25
If you have a PL25 boiler, please check if all 14 of the turbo– gratings are hanging correctly in place in
the heat exchanger before starting it for the first time.
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Abbildung 10: Cleaning lid of the heat exchanger
Abbildung 11: Heat exchanger with turbo–gratings and operating lever
Open the cleaning lid of the heat exchanger and check if all turbo–gratings are in place. Caution: The
turbo–gratings can have sharp edges and, therefore, protective gloves should be worn.
With the PL25, the turbo gratings are linked to the ash–removing lever of the baffle plate. If the appropriate
lever on the left side of the boiler is activated, the turbulators will move up and down. This action
cleans the heat exchanger. The cleaning procedures, as described in chapter fullrefpc1 would, therefore,
be unnecessary.
1.17 Operation
1. Conveyor screw motor
2. Plug for the conveyor screw motor
3. Emptying lid for the pellet bin
4. Vacuum sensor
5. Burner drawer with automatic de–ashing of the fire pan
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6. Fuse box
7. Downpipe for the pellets
8. Burner pipe
9. Main pipe for the fuse cable
Abbildung 12: Pellet boiler
Abbildung 13: Overview of the PL15 mechanism
If the boiler has been fully connected to the heating system with both water and electricity supplies, the
PL can be operated.
At first, the pellet bin must be filled up. The filling is done by hand. We recommend that the bin should
always be filled up to the top to ensure a good, long operation.
The filling up of the pellet storage bin can also be done automatically with the aid of an optional external
feeding facility. Further information about his can be found in our material.
Important: The KUENZEL pellet boiler is equipped with an automatic fire pan ash–emptier. The ash–
emptying cycle is introduced after each burn–out. If there’s no burn–out for a certain amount of time, the
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control panel will induce a burn–out and, in turn, an ash–emptying cycle will start. Further details about
this can be found in the control panel instructions manual.
When the pellet storage bin has been filled with fuel, the boiler can be operated. There are two different
basic modes of operation:
1.17.1 Operation without Heating Electronics
In the standard version, the PL is operated without weather–responsive heating electronics. In order
to set the boiler in operation, the control panel is switched on at the ON/OFF switch. Then the boiler
begins with the ignition. The remaining minutes of the ignition period appears in the left–hand segment
of the display. The ignition process finishes either at the end of the ignition period or when the control
panel has recognized that the pellets have definitely been ignited due to a sudden rise in the exhaust gas
temperature.
The PL should now run at full load operation until the boiler reaches a temperature 10 K (you can choose
a value between 30 K and 10 K) below the pre–set boiler target temperature. If this happens, the PL
will switch itself automatically to partial load operation. If the boiler temperature decreases under the
threshold value again, the PL will switch itself back onto full power.
Should the boiler exceed the pre–set boiler target temperature, despite the boiler being in partial load
operation, the burner switches itself off. In the left segment of the display, the letter „A“appears. If the
exhaust gas temperature falls under 90◦ C, the letter „E“appears in the display. The pellet boiler now goes
through an automatic fire pan ash–emptying cycle. As soon as the temperature sinks under the adjustable
switch-on temperature (pre–set by factory onto 70o C) again, the burner starts automatically and the work
cycle begins again.
If the PL shall be stopped, the START button must be pressed again until the letter „A“appears in the left
segment of the display.
The boiler target temperature can be set between 80o C and 87oC. The long hysteresis between the points
of turning on and off ensures that the burner runs for a long time. This ensures that the operation runs
more economically and with low emissions.
1.17.2 Operation with Heating Electronics
A PL can be optionally equipped with weather–regulated heating electronics from KUENZEL. It should
also be noted that the connection box of the type no. 150252 is compulsory for the operation with
weather–influenced heating electronics. Caution: A cable must be fitted by client from the connection
box to the burner point of contact on the 806–control panel. The clamps 1 and 2 of the connection
box should be connected to the clamps 3 and 4 of the bottom sensor plugs on the 806.
In order to ensure that operation runs in the best possible way, the steepness of heating characteristics of
the boiler circulation should be set to 2.5, the burner–switch difference to 10 K, the minimum running
time of the burner to 10 minutes and the boiler maximum temperature to 85o C. The boiler and the tank
start relief are switched on. These jobs are only allowed to be carried out by a heating technician.
To reassure that the Control Panel 806 recognises the heating electronics correctly, move the DIP–switch
on the back of the control panel into the position „heating electronics“˙To do this, read also the appropriate
chapter in the control panel manual.
In order to set the boiler in operation, the control panel should be switched on using the ON/OFF switch.
Then the START–button should be pressed. If now the heating electronics request heat from the burner,
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the PL begins the ignition. The remaining ignition time in minutes appears in the left segment of the
display. The ignition process finishes either at the end of the ignition time or when the control panel, due
to a sudden rise in the exhaust gas temperature, has recognized that the pellets have already been ignited.
The PL now runs at full boiler power until the boiler reaches a temperature 10 K (adjustable between 30
K and 10 K) below the pre–set boiler target temperature. If this happens, then the PL switches itself into
partial load operation automatically. If the boiler temperature drops under the threshold value again, then
the PL switches itself back onto full power again.
The PL remains in operation until the heating electronics demand no more heat from the burner. In the
left segment of the display, the letter „A“appears. If the exhaust gas temperature falls below 90◦ C, the
letter „E“appears in the display. The pellet boiler then passes through an automatic fire pan ash–emptying
cycle. If the heating electronics request heat from the burner again, the PL starts once more.
We recommend the KUENZEL weather–regulated heating electronics for all heating systems, in which
the PL functions as the single source of heat.
1.17.3 Operation with Buffer Storage
The PL can also be operated with buffer storage. We recommend the operation with buffer storage as it
enables a longer running time of the burner, as well if only little heat is demanded. This way emissions
and the general wear and tear can be reduced.
If the buffer storage is integrated into the system, the two buffer sensors have to be joined to the 806 Control
Panel and assessed. The boiler can, as described above, be started. There are two possible operation
modes:
Operation without heating electronics The boiler stays in operation until the boiler temperature exceeds
the boiler target temperature. Now a burn-out begins. As soon as the exhaust gas temperature falls
below 90◦C the buffer temperature will be controlled. If now the upper buffer temperature is higher than
the set switch-over temperature, the boiler circulation pump stops. The upper buffer temperature has to
fall below the switch-over temperature, before the boiler circulation pump starts again. The burner will
stay blocked as well until the upper buffer temperature falls below the switch-over temperature, even if
the boiler temperature falls below 70◦C. Operation with heating electronics If there is a request of the heating electronics on the burner, the
boiler circulation pump is switched on. If the heating electronics’ request stops, the boiler circulation
pump keeps on working until a burn-out starts. If the boiler reaches a temperature 2◦ C (adjustable) above
the lower buffer temperature, the boiler circulation pump stops. The boiler circulation pump starts again,
if the boiler reaches a temperature 2◦C (adjustable) below the upper buffer temperature or if the heating
electronics send a new request.
1.18 Maintenance and Service
As with all technical appliances, your pellet boiler must be regularly checked and serviced. Depending
on the cleaning function, the different cleaning intervals should be kept. An additional thorough service
should be carried out before long periods of disuse such as before the summer holidays.
We recommend that you arrange a service contract with your heating technician.
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1.18.1 Monthly Cleaning
Abbildung 14: Taking out the burner drawer
Once a month, the ashtray has to be emptied. To do this, switch off the boiler by pressing the
START/STOP button on your control panel and then wait until the boiler reaches the state of burn–
out. Now the ash–door can be opened and the ashtray taken out. Be aware that the hot ash should not be
put into a container which is either made of flammable material or contains flammable material in it.
The fire pan must also be checked at least once a month to ensure that it runs smoothly and reliably.
When the boiler is switched off, open the ash–door. Then disconnect the fuse–cable plug and the plug
for the ash–emptying motor and put the pipe for the cable towards the front so that it is out of the way.
The burner drawer [12] with the fire pan [13] can then be pulled in a forward direction and then removed
from the boiler.
Caution: Around the burner–drawer, there could still be hot or glowing traces of ash. So, only put the
burner–drawer on top of a fire–proof surface.
Next, the fire pan can be taken out of the burner–drawer with a slight lift in a backwards direction.
Then remove all traces of ash from the fire pan and from the bottom of the drawer. All holes in the fire
pan must also be free of ash traces. Likewise, any ash in the fuse–pipe should also be removed. [14].
Move the burner–drawer and check the boost–link [16] and the area [17] at the drawer[15]. Any stuck
ash also needs to be removed.
After the thorough cleaning, the fire pan is put back into the burner–drawer. Be careful that the fuse–pipe
is put back into the appropriate hole in the fire pan. The fuse–pipe should be pushed that far into the fire
pan that 1mm to 2mm is showing.
Now push the burner–drawer back into its place. Make sure that the drawer is pushed in properly until
its end position.
The pipe for the cables needs to be put back into place and the plugs reconnected.
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Abbildung 15: Fitting position of the fire pan
Abbildung 16: Taking out the fire pan
18

Abbildung 17: Drawer bottom of the fire pan ash–emptier
Abbildung 18: Heat exchanger with turbo–gratings and operating lever
19

Abbildung 19: Operating lever for the heat exchanger cleaning
20

1.18.2 Additional Half–Yearly Cleaning
Abbildung 20: Heat exchanger with turbo gratings and dust catch (middle). Exhaust gas sensor above
right
Abbildung 21: Burner pipe with overlay
In order to guarantee a constant and reliable function of your pellet boiler, it is necessary to clean the
ventilator. To do this, please read chapter 1.18.3 auf Seite 23.
To maintain the PL’s high level of efficiency, the flue gas ducts must also be cleaned. To do this, take off
the red top casing behind the control panel and then open the cleaning hatch which lies underneath it.
Now the flue gas ducts and the upper dust catch are visible. The dust catch can be cleaned with a vacuum
cleaner. Make sure, though, that the exhaust gas sensors do not become damaged or pushed out of place.
With the PL25, a manual cleaning of the heat exchanger is not necessary.
The flue gas ducts can be cleaned thoroughly using the cleaning brush. It may be necessary for the dust
catch to be vacuumed once again after the flue gas ducts have been cleaned. Finally, the cleaning lid and
the red casing can be closed again.
Then push down the appropriate lever on the left side of the boiler in order to clean the baffle–plate.
For removing all traces of ash from the boiler which were scattered when the flue gas ducts were cleaned,
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Abbildung 22: Disassembly of the fuse box
Abbildung 23: Fuse
open the ash–door and take out the burner–drawer, as described in chapter1.18.1 auf Seite 17.
Next, lift the burner–pipe [8] carefully, pull it to the left and then remove it from the boiler.
Subsequently, the end–piece of the down–pipe [7] should be taken out of the boiler. To do this, the
tightening screw needs to be loosened. The end–piece can now be pulled out from the down–pipe. Lift
out the burner–pipe overlay [10] from its position and remove it from the boiler. Then the burner overlay
[11] needs to be lifted out of place and taken out of the boiler in a forwards motion.
Finally, the ashtray should be taken out of the boiler. The remaining ash can be removed from the boiler
with a vacuum cleaner.
After a thorough cleaning around the burner area, all parts need to be reassembled in reverse order.
The pellet bin should be completely emptied during its half–yearly cleaning procedures. Any existing
automatic filling facilities are to be switched off. The wood–powder, which is to be found in the pellet–
bin, can be removed with the pellet bin–emptier [3] or with a vacuum cleaner.
During the half–yearly cleaning procedures, the fuse element must also be checked and cleaned. To do
this, loosen the tightening screw of the fuse box [6] and pull it through the hole in the fire pan and then
out of the burner–drawer.
After the service has been completed and the fuse element cleaned, the boiler has to be reassembled in
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everse order.
1.18.3 Ventilator
Abbildung 24: Exhaust gas ventilator
Abbildung 25: Inner view of the ventilator
Caution: Before working on the ventilator, pull out the mains plug from its socket without fail!
Due to the dust in the exhaust gas, the ventilator will become dirty. The dust settles on the blades of the
ventilator and slows it down so that it can no longer drive the gas through adequately. Dust on the blades
can also lead to run–outs. This could considerably reduce the life–span of the motor system. Therefore,
the ventilator must be cleaned at least twice a year! If the ventilator produces uncustomary noises
or run–outs whilst in operation and it is not yet due to be cleaned then an earlier cleaning should be
arranged.
For the cleaning, the ventilator can remain in place. Only the entity of motor and ventilator wheel needs
to be removed from its case.
To do this, disconnect the ventilator cable, loosen the screws at the motor–flange and pull out the motor
with the ventilator–wheel from the case.
The ventilator–wheel is now freely accessible from all sides and can be cleaned i.e. with compressed air
(ventilator–wheel must be held tightly!) or with a brush. When doing so, the upcoming dust should be
23

emoved with a vacuum cleaner from time to time. Do not forget to vacuum inside the ventilator case as
well!
After cleaning, the ventilator needs to be reassembled in reverse order.
Caution: Be aware that during the first run after the cleaning, heavy dust could build up.
If you have any questions or problems concerning your KUENZEL Pellet Boiler, please contact either
your heating installer or your national KUENZEL agent. (See bf www.kuenzel.de).
2 The KUENZEL Thermomix Valve
Abbildung 26: Thermomix Valve Functions Diagram
The KUENZEL Thermomix Valve is an automatic boiler back-end protection which does not require
any other additional energy resources. The return-flow water, which comes out cold from the heating
system, is pre-heated with hot flow-pipe water to a minumum of 63o C. This temperature is above the
dew-point of the exhaust gas in the boiler, so that a build-up of condensation and premature damage of
the boiler through corrosion can be avoided. The benefit of the boiler circulation pump (15) is not only
for the bypass, but also as a loading facility for the buffer storage. The Thermomix Valve can be adjusted
to match a boiler power of up to 50kW.
Connections: In-put R 1 1/2“ , out-put R 1 1/2“˙A swivel-nut must fit the pump connection.
Assembly: We recommend the installation with flat gaskets and stop valves at all three in-put points.
This makes the service and maintenance easier because the whole system does not have to be emptied.
The flaptrap of the Thermomix Valve must be kept shut when the system is being installed. If necessary,
turn the inserted plastic part in the appropriate direction. Please be aware of the direction of the current!
When the valve is being assembled, please use a pair of pliers.
Service: Once a year, the valve must be opened up and cleaned. The expansion cartridge should be
replaced after 5 years as a precautionary measure. If a fault occurs, all movable parts can be taken out
using the lid at the side. This makes the cleaning and also the replacement of parts easier, as it saves
having to take the whole Thermomix Valve out.
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Abbildung 27: Plan of a system with Thermomix Valve
1. Cold-start phase: Flow and Return are cold (less than 63o C). The Thermomix is open for the
bypass only; the flap trap is closed and keeps the return water out.
2. Mix-phase: The water from the flow is warmer than 63oC, it becomes mixed up with enough cold
water from the return to raise the return temperature to 63o C.
3. The return temperature is warmer than 63 o C. The bypass is shut.
For the meaning of the numbers in the pictures, please refer to the key in chapter2.1 auf Seite 26
25

2.1 Legend to the Plans
No. Part
1 HV–boiler
2 HV–control panel
3 Oil–gas–boiler
4 Oil–gas–boiler–control panel
5 Heating electronics
6 Thermomix–Valve
7 Buffer tank PS
8 Combined buffer / hot water tank PSB
10 Hot water tank HSR / TS
11 Reversing valve
12 Three–way–mixer
13 Set of fittings
14 Wall mounting box
15 Boiler circulation pump
16 Oil boiler pump
17 Boiler sensor of the heating electronics
18 Heating circuit pump
19 Heating system
20 Hot water tank charge pump
21 Flap trap
22 Contact thermostat
23 Pedestal for the oil boiler
24 Supporting pump
25 Instantaneous gas hot water heater
26 Automix
27 Hot water thermostat
28 Combi–tank PSG
29 Solid fuel boiler FO15
30 Thermostat 1x change–over contact
31 Solar panel
32 Layer storage tank
33 Solar hot water tank
34 Solar control panel
35 Solar station
36 PL15
37 Four–way–mixer
38 Contact thermostat
39 Central heating cooker
40 pump / change–over control
26

3 System Suggestions for the PL
3.1 Package PL1 for Pellet Boilers with Hot Water Tank
This suggestion for a pellet boiler heating system according tosystem package PL1, shows how to build
an uncomplicated, economical and small heating installation with a regulated hot water tank.
The PL may only be operated with a boiler back–end protection. The 4–way mixer [37] serves as boiler
back–end protection and heating mixer at the same time and also protects your boiler from corrosion.
The regulation of the PL, of the hot water tank and of the 4–way mixer is done by the integrated optional
heating electronics.
The minimum boiler temperature delimination of the heating electronics must be set to 50o C; the burner
switch–difference to 15oC. Please consult the heating electronics instructions on this subject.
Before installing the system, please read the operation and assembly instructions of all appliances. Make
sure that the boiler control panel feelers do not become mixed up with those of the heating electronics.
The wiring of the system must only be carried out by an electrician; PVC cables must not be fitted into
the boiler.
The electro–connection is made after the electro–plan to the system package PL1.
3.1.1 Hydraulic–Plan
Abbildung 28: System Package PL1
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3.1.2 Electro–Plan
Abbildung 29: Electro–plan to the package PL1
3.2 Package PL2 for Pellet Boilers with Hot Water Tank and Buffer Storage
This suggestion for a pellet boiler heating system according tosystem–package PL2 shows how to build
an uncomplicated, economical and small pellet heating installation with regulated hot water tank and
buffer storage. With this system, a 4–way mixer as boiler back–end protection is not enough. It should,
therefore, be provided with a Thermomix Valve.
Make sure that the boiler circulation pump (15) and the heating circuit pump (18) match up with each
other correctly. Please also read the section „Fitting the boiler back–end protection“ in our technical
material for this.
We recommend that the Thermomix–Valve and the buffer storage are installed in such a way that they
can be blocked on all sides so that an easier service is possible.
The minimum boiler temperature delimination of the heating electronics must be set to 60o C; the burner–
switch difference to 15oC. Please read the heating electronics instructions to do this.
Before installing the system, please read the operation and assembly instructions of all appliances to
make sure that the boiler control panel sensors do not become mixed up with those of the heating electronics.
The wiring of the system must only be carried out by an electrician; PVC cables must not be
used in the boiler.
The electro–connection is made after the electro–plan to the system package PL2.
28

3.2.1 Hydraulic–Plan
3.2.2 Electro–Plan
Abbildung 30: System Package PL2
Abbildung 31: Electro–plan to the packet PL2
3.3 Package PL3 for Pellet Boilers with a Combi–Tank
This suggestion for a pellet boiler heating system according to system packet PL3 shows how to build
an uncomplicated, economical and small heating installation with a combi–tank, including the buffer
storage and the unregulated hot water tank in one. With this system, a 4–way mixer as the boiler back–
end protection is not enough. It must, therefore, be provided with a Thermomix Valve. The installation
diagram is particularly suitable also for the construction of a heating–supporting solar–installation.
Make sure that the boiler circulation pump (15) and the heating circuit pump (18) are correctly coordinated
with each other. To do this, please read the section „Fitting the boiler circulation pump“ in our
technical material.
We recommend that the Thermomix Valve and the combi–tank are installed in such a way that they can
be blocked on all sides so that the system is easy to service.
29

The minimum boiler temperature delimination of the heating electronics must be set to 60o C; the burner–
switch difference to 15oC. Please also read the heating electronics instructions for this.
Before installing the system, please read the operation and assembly instructions of all appliances. Make
sure that the sensors of the boiler control panel do not get mixed up with those of the heating electronics.
The wiring of the installation must only be carried out by a qualified electrician; PVC cables must not be
fitted into the boiler.
Pay attention to the state of the sacrificial anode in the hot water tank as faulty anodes can lead to
premature damage of the boiler. We recommend that the anode should be checked at least once a year.
The electric connection is made after the electro–plan for the system package PL3.
3.3.1 Hydraulic–Plan
3.3.2 Electro–Plan
Abbildung 32: System Package PL3
Abbildung 33: Electro–plan for system package PL3
30

4 Connection Box for the Heating Electronics Type Theta
With the control panels 806, 812 and 821 from KUENZEL, there is the possibility to integrate weather–
influenced heating electronics of the types Theta E23B or E233B into the control panel. To do this, this
connection box is needed.
4.1 Assembly
Abbildung 34: The connection box
Abbildung 35: Control Panel 806 rear view
The assembly of the connection box must only be carried out by a qualified electrician. For any jobs
on the connection box or on its wiring, the whole heating system must be totally disconnected from the
mains.
The length of the connecting cable is approx. 3 meters. The connection box can either be assembled on
the wall of the installation room or on the boiler–wall.
When assembling the box onto the pellet–boiler PL15, we recommend that it should be assembled in the
space underneath the pellet fuel storage bin. The cables are placed from behind the coating sheet of the
boiler in an upwards direction to the control panel.
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Description Lay–Out Connection Box Screws EBV Theta
burner–relay T1 1 1
T1 2 2
direct heating circuit pumps L1 3 3
N 4 N
PE 5 PE
charge pump for the hot water tank L1 6 5
N 7 N
PE 8 PE
mixer 1 L1 (Auf) 9 7
L2 (Zu) 10 8
N 11 N
PE 12 PE
pump mixer 1 L1 13 9
N 14 N
PE 15 PE
mixer 2 (E233B) L1 (Auf) 21 13
L2 (Zu) 22 14
N 23 N
PE 24 PE
pump mixer 2 (E233B) L1 25 15
N 26 N
PE 27 PE
flow sensor 2 (E233B) brown 28 33
white 29 23
flow sensor 1 brown 30 29
white 31 23
hot water tank sensor brown 32 28
white 33 23
boiler sensor brown 34 27
white 35 23
external sensor brown 36 26
white 37 23
Connect the plug X1 to X4 to the appropriate contact–points on the heating electronics. The brown 3–
pole plug must be connected to the control 812 / 806. To do this, it is necessary to take off the metal
safety plate above the plug at the back of the control panel.
The consumer is connected according to the following table. The connections mixer 2 and pump mixer
2 are only used for two mixed heating circuits when a E233B is inserted.
Only 806: So that the control panel 806 can recognize the burner contact of the heating electronics, the
contact–points 1 and 2 of the connection box must be connected to the contact–points 3 and 4 (weather–
influenced heating electronics) with a cable fitted by client at the bottom 10–pole–feeler plug of the
control panel 806.
32

Index
Boiler Back–End Protection, 5
chimney calculations
PL, 7
cleaning
1/2 yearly
PL, 21
weekly
PL, 17
control panel
assembly
PL, 9
Electric Heating Cartridge, 10
External Feeding of the Pellets, 11
Factory Number, 5
heating connection
PL, 7
pellet bin
attachment, 12
PL25
turbulators, 12
System Package PL1, 27
System Package PL2, 28
System Package PL3, 29
Systempakete
Legende, 26
The Identification Plate, 5
Thermomix Valve, 24
Thermomix-Valve
Assembly, 24
Function, 25
ventilator
outer view, 23
assembly, 8, 9
cleaning, 23
view, 23
33