Fröling SP Dual compact User manual

Installation instructions
Dual fuel boiler SP Dual compact
Translation of original German version of installation instructions for technicians.
Read and follow all instructions and safety instructions.
All errors and omissions excepted.
M1820921_en | Edition 12/07/2021

Contents
ii M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
1 General ......................................................................................................................................................... 4
1.1 About this manual ................................................................................................................................. 4
2 Safety............................................................................................................................................................ 5
2.1 Hazard levels of warnings..................................................................................................................... 5
2.2 Qualification of assembly staff .............................................................................................................. 6
2.3 Personal protective equipment for assembly staff ................................................................................ 6
3 Design Information...................................................................................................................................... 7
3.1 Overview of standards .......................................................................................................................... 7
3.1.1 General standards for heating systems ..................................................................................... 7
3.1.2 Standards for structural and safety devices............................................................................... 7
3.1.3 Standards for heating water....................................................................................................... 7
3.1.4 Regulations and standards for permitted fuels .......................................................................... 8
3.2 Installation and approval....................................................................................................................... 8
3.3 Installation site ...................................................................................................................................... 8
3.4 Chimney connection/chimney system .................................................................................................. 9
3.4.1 Connection line to the chimney.................................................................................................. 9
3.4.2 Measuring port........................................................................................................................... 10
3.4.3 Draught limiter............................................................................................................................ 10
3.4.4 Explosion flap............................................................................................................................. 10
3.4.5 Electrostatic particle separator................................................................................................... 11
3.5 Combustion air...................................................................................................................................... 12
3.5.1 Combustion air supply at the installation room .......................................................................... 12
3.5.2 Simultaneous operation with other air-drawing systems............................................................ 13
3.6 Domestic hot water ............................................................................................................................... 14
3.7 Pressure maintenance systems............................................................................................................ 15
3.8 Storage tank ......................................................................................................................................... 16
3.9 Return lift .............................................................................................................................................. 17
3.10 Boiler ventilation ................................................................................................................................... 17
4 Technical information ................................................................................................................................. 18
4.1 Dimensions SP Dual compact .............................................................................................................. 18
4.2 Components and connections .............................................................................................................. 19
4.3 Technical specifications........................................................................................................................ 20
4.3.1 SP Dual compact 15/20 ............................................................................................................. 20
4.3.2 Boiler data for planning the flue gas system.............................................................................. 22
4.4 External suction module ....................................................................................................................... 23
5 Transport and storage ................................................................................................................................ 24
5.1 Delivery configuration ........................................................................................................................... 24
5.2 Temporary storage ............................................................................................................................... 24
5.3 Positioning ............................................................................................................................................ 25
5.4 Positioning at the installation site.......................................................................................................... 25
5.4.1 Removing boiler from pallet ....................................................................................................... 25
5.4.2 Removing the pellet unit from the pallet..................................................................................... 27
5.4.3 Operating and maintenance areas of the equipment................................................................. 28
6 Installation.................................................................................................................................................... 30
6.1 Required accessories and tools............................................................................................................ 30
6.2 Accessories supplied ............................................................................................................................ 30
6.3 Assembly overview pellet unit............................................................................................................... 31
6.4 Assembly overview S1 Turbo (F).......................................................................................................... 32

Contents
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact iii
6.5 Before Installation ................................................................................................................................. 34
6.5.1 Changing door stops (as needed).............................................................................................. 34
6.5.2 Checking the seal on the doors ................................................................................................. 36
6.5.3 Positioning the doors ................................................................................................................. 37
6.6 Install firewood boiler ............................................................................................................................ 38
6.6.1 Fit the induced draught fan ........................................................................................................ 38
6.6.2 Installing the insulation............................................................................................................... 38
6.6.3 Fitting the air control .................................................................................................................. 42
6.6.4 Installing the WOS lever ............................................................................................................ 43
6.6.5 Install the drive for the automatic WOS (optional) ..................................................................... 43
6.6.6 Installing the insulated door ....................................................................................................... 46
6.6.7 Fitting the controller box............................................................................................................. 48
6.6.8 Installing the Lambda probe, sensor and thermal discharge valve............................................ 48
6.6.9 Attaching the induced draught cable.......................................................................................... 49
6.7 Fitting the pellet unit.............................................................................................................................. 50
6.7.1 Screw the pellet unit to the firewood boiler ................................................................................ 50
6.7.2 Fitting the air connection............................................................................................................ 54
6.7.3 Fitting the cladding to the pellet unit .......................................................................................... 54
6.8 Connecting the discharge system......................................................................................................... 56
6.8.1 Installing the external suction module........................................................................................ 56
6.8.2 Connecting the hose lines.......................................................................................................... 58
6.8.3 Assembly information for hose lines .......................................................................................... 59
6.9 Hydraulic connection ............................................................................................................................ 61
6.10 Electrical connection............................................................................................................................. 63
6.10.1 Board overview .......................................................................................................................... 64
6.10.2 Connect the firewood boiler components................................................................................... 65
6.10.3 Connect the components of the pellet unit................................................................................. 66
6.10.4 Potential equalisation................................................................................................................. 69
6.11 Final installation steps .......................................................................................................................... 70
6.11.1 Positioning the boiler stickers .................................................................................................... 71
6.11.2 Affixing the identification plate ................................................................................................... 72
6.11.3 Insulate the connection line ....................................................................................................... 72
6.11.4 Install the brackets for accessories............................................................................................ 73
7 Start-up......................................................................................................................................................... 74
7.1 Before commissioning / configuring the boiler ...................................................................................... 74
7.2 Initial startup ......................................................................................................................................... 75
7.2.1 Permitted fuels........................................................................................................................... 75
7.2.2 Fuels permitted under certain conditions................................................................................... 76
7.2.3 Non-permitted fuels.................................................................................................................... 77
7.2.4 Heating up for the first time........................................................................................................ 77
8 Decommissioning........................................................................................................................................ 78
8.1 Mothballing ........................................................................................................................................... 78
8.2 Disassembly ......................................................................................................................................... 78
8.3 Disposal ................................................................................................................................................ 78
9 Appendix ...................................................................................................................................................... 79
9.1 Pressure equipment regulation............................................................................................................. 79

1 | General
4 M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
1 General
Thank you for choosing a quality product from Froling. The product features a state-of-
the-art design and conforms to all currently applicable standards and testing guidelines.
Please read and observe the documentation provided and always keep it close to the
system for reference. Observing the requirements and safety information in the
documentation makes a significant contribution to safe, appropriate, environmentally
friendly and economical operation of the system.
The constant further development of our products means that there may be minor
differences from the pictures and content. If you discover any errors, please let us know:
[email protected].
Subject to technical change.
Issuing a delivery
certificate The EC Declaration of Conformity is only valid in conjunction with a delivery certificate,
which has been filled in correctly and signed as part of the commissioning process. The
original document remains at the installation site. Commissioning installers or heating
engineers are requested to return a copy of the delivery certificate together with the
guarantee card to Froling. On commissioning by FROLING Customer Service the validity
of the delivery certificate will be noted on the customer service record.
1.1 About this manual
These installation instructions contain information for the following sizes of SP Dual
compact boilers:
SP Dual compact 15, SP Dual compact 20

Safety | 2
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact 5
2 Safety
2.1 Hazard levels of warnings
This documentation uses warnings with the following hazard levels to indicate direct
hazards and important safety instructions:
DANGER
The dangerous situation is imminent and if measures are not observed it will lead
to serious injury or death. You must follow the instructions!
WARNING
The dangerous situation may occur and if measures are not observed it will lead to
serious injury or death. Work with extreme care.
CAUTION
The dangerous situation may occur and if measures are not observed it will lead to
minor injuries.
NOTICE
The dangerous situation may occur and if measures are not observed it will lead to
damage to property or pollution.

2 | Safety
6 M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
2.2 Qualification of assembly staff
CAUTION
Assembly and installation by unqualified persons:
Risk of personal injury and damage to property
During assembly and installation:
rObserve the instructions and information in the manuals
rOnly allow appropriately qualified personnel to work on the system
Assembly, installation, initial startup and servicing must always be carried out by qualified
personnel:
- Heating technician / building technician
- Electrical installation technician
- Froling customer services
The assembly staff must have read and understood the instructions in the documentation.
2.3 Personal protective equipment for assembly staff
You must ensure that staff have the protective equipment specified by accident
prevention regulations!
▪ During transport, erection and installation:
- wear suitable work wear
- wear protective gloves
- wear safety shoes (min. protection class S1P)

Design Information | 3
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact 7
3 Design Information
3.1 Overview of standards
Perform installation and commissioning of the system in accordance with the local fire
and building regulations. Unless contrary to other national regulations, the latest versions
of the following standards and guidelines apply:
3.1.1 General standards for heating systems
EN 303-5 Boilers for solid fuels, manually and automatically fed combustion
systems, nominal heat output up to 500 kW
EN 12828 Heating systems in buildings - design of water-based heating
systems
EN 13384-1 Chimneys - Thermal and fluid dynamic calculation methods
Part 1: Chimneys serving one appliance
ÖNORM H 5151 Planning of central hot water heating systems with or without hot
water preparation
ÖNORM M 7510-1 Guidelines for checking central heating systems
Part 1: General requirements and one-off inspections
ÖNORM M 7510-4 Guidelines for checking central heating systems
Part 4: Simple check for heating plants for solid fuels
3.1.2 Standards for structural and safety devices
ÖNORM H 5170 Heating installation - Requirements for construction and safety
engineering, as well as fire prevention and environmental protection
ÖNORM M 7137 Compressed untreated wood – Requirements for storing pellets at
the end customer’s site
TRVB H 118 Technical directives for fire protection/prevention (Austria)
3.1.3 Standards for heating water
ÖNORM H 5195-1 Prevention of damage by corrosion and scale formation in closed
warm water heating systems at operating temperatures up to 100°C
(Austria).
VDI 2035 Prevention of damage hot water heating systems (Germany)
SWKI BT 102-01 Water quality for heating, steam, cooling and air conditioning
systems (Switzerland)
UNI 8065 Technical standard regulating hot water preparation.
DM 26.06.2015 (Ministerial Decree specifying the minimum
requirements)
Follow the instructions of this standard and any related updates.
(Italy)

3 | Design Information
8 M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
3.1.4 Regulations and standards for permitted fuels
1. BImSchV First Order of the German Federal Government for the
implementation of the Federal Law on Emission Protection
(Ordinance on Small and Medium Combustion Plants) in the version
published on 26 January 2010,
BGBl. JG 2010 Part I No. 4.
EN ISO 17225-2 Solid bio-fuel - Fuel specifications and classes
Part 2: Wood pellets for use in industrial and domestic systems
EN ISO 17225-3 Solid bio-fuel - Fuel specifications and classes
Part 3: Wood briquettes for non-industrial use
EN ISO 17225-5 Solid bio-fuel - Fuel specifications and classes
Part 5: Firewood for non-industrial use
3.2 Installation and approval
The boiler should be operated in a closed heating system. The following standards
govern the installation:
Note on standards EN 12828 - Heating Systems in Buildings
IMPORTANT: Every heating system must be officially approved.
The appropriate supervisory authority (inspection agency) must always be informed when
installing or modifying a heating system, and authorisation must be obtained from the
building authorities:
Austria: report to the construction authorities of the community or magistrate
Germany: report new installations to an approved chimney sweep / the building
authorities.
3.3 Installation site
Requirements for the load bearing substrate:
▪ Flat, clean and dry
▪ Non-combustible and with sufficient load-bearing capacity
Conditions at the installation site:
▪ Frost-free
▪ Sufficiently well lit
▪ Free of explosive atmospheres such as flammable substances, hydrogen halides,
cleaning agents and consumables
▪ Installation at altitude higher than 2000 metres above sea level only after consultation
with the manufacturer
▪ The system must be protected against gnawing and nesting by animals (such as
rodents)
▪ No flammable materials in proximity to the system

Design Information | 3
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact 9
3.4 Chimney connection/chimney system
1
2
3
4
5
1Connection line to the chimney
2Measuring port
3Draught limiter
4Explosion flap (for automatic boilers)
5Thermal insulation
NOTICE!The chimney must be authorised by a smoke trap sweeper or chimney
sweep.
The entire flue gas system (chimney and connection) must be laid out as per ÖNORM /
DIN EN 13384-1 or ÖNORM M 7515 / DIN 4705-1.
The flue gas temperatures (for clean systems) and additional flue gas values can be
found in the table in the technical data.
Local regulations and other statutory regulations are also applicable.
EN 303-5 specifies that the entire flue gas system must be designed to prevent, wherever
possible, damage caused by seepage, insufficient feed pressure and condensation.
Please note within the permissible operating range of the boiler flue gas temperatures
lower than 160K above room temperature may occur.
3.4.1 Connection line to the chimney
Requirements got the connection line:
▪ This should be as short as possible and follow an upward incline to the chimney (30 -
45° (recommended)
▪ Leak-tight against overpressure
▪ Thermal insulation recommended
Distance from flammable components:
▪ 100 mm if at least 20 mm thermal insulation is installed
▪ 375 mm if no thermal insulation is present
Recommendation: three times the diameter of the connection line

3 | Design Information
10 M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
3.4.2 Measuring port
For emissions measurement on the system, a suitable measuring port must be installed
in the connection line between the boiler and chimney system.
2 x D
D
D
M
Upstream of the measuring port (M) there should be a straight run-in section with a length
about twice the diameter (D) of the connection line. Downstream of the measuring port
(M) there should be a straight run-out section with a length about the diameter (D) of the
connection line. The measuring port must remain closed whenever the system is in
operation.
The diameter of the measuring probe used by Froling customer service is 14 mm. To
avoid measuring errors due to the ingress of false air, the diameter of the measuring port
must not exceed 21mm.
3.4.3 Draught limiter
We generally recommend the installation of a draught limiter. A draught limiter must be
installed if the maximum permissible feed pressure as given in the boiler data for planning
the flue gas system is exceeded.
NOTICE!Install the draught limiter directly under the mouth of the flue line, as the
pressure is constantly low at this point.
3.4.4 Explosion flap
TRVB H 118 (only Austria) stipulates that an explosion flap must be installed in the
connection line to the chimney, directly next to the boiler. It should be situated in such a
way that is poses no risk to persons!

Design Information | 3
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact 11
3.4.5 Electrostatic particle separator
For reduction in the emissions an electrostatic particle separator may optionally be
installed in the flue gas line.
D
D
M
2 x D
E
For planning and installation, comply with the following points:
▪ Position the measuring port (M) downstream of the electrostatic particle separator (E)
as specified in the instructions
Ü "Measuring port" [}10]
▪ Locate the electrostatic particle separator in accordance with the planning for the flue
gas system
▪ Install the electrostatic particle separator in accordance with the manufacturer's
instructions supplied

3 | Design Information
12 M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
3.5 Combustion air
12
4
3
1Boiler in room air-dependent operation
2Air extraction system (such as centralised dust extraction system, room ventilation)
3Under-pressure monitoring system
4Combustion air supply from outside
3.5.1 Combustion air supply at the installation room
The system is operated in open flue mode, i.e. the combustion air required to operate the
boiler is drawn from the installation room.
Requirements:
▪ Opening to the atmosphere
– Weather conditions must not affect the air flow in any way (e.g. snow and foliage)
– Cross-section area free of obstructions such as cover gratings and slats
▪ Air supply lines
– For air supply lines longer than 2 metres and where mechanical means are used
to feed combustion air, the flow rate must be calculated (maximum flow rate = 1 m/
s)
Note on standards ÖNORM H 5170 - Construction and fire protection requirements
TRVB H118 - Technical directives on fire protection/prevention

Design Information | 3
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact 13
3.5.2 Simultaneous operation with other air-drawing systems
Where the boiler is operated in room air-dependent mode with simultaneous operation of
other air-drawing systems (such as room ventilation), safety devices are necessary:
▪ Air pressure monitor
▪ Flue gas thermostat
▪ Window-tilting drive system, window-tilting switch
NOTICE!Clarify the safety devices with appropriate flue sweep / chimney sweep
Recommendation for room ventilation:
Use “intrinsically-safe” room ventilation systems with F classification
As a basic rule:
▪ Room under-pressure max. 8Pa
▪ Air-drawing systems must not exceed the room under-pressure value
– If the room under-pressure value is exceeded, safety equipment (under-pressure
monitoring system) is necessary
In Germany, the following additional requirement must be observed:
DiBt requires that an approved under-pressure monitoring system (such as air pressure
monitor P4) which monitor the maximum under-pressure to 4 Pa must be installed in the
installation room.
In addition, at least one of the following three requirements must be met:
(Source: Section 4 MFeuV 2007 / 2010)
▪ Dimension the cross-section of the combustion air opening so that when the boiler is
in operation the maximum under-pressure is not exceeded (simultaneous operation)
▪ Use safety equipment that prevents simultaneous operation (alternate operation)
▪ Monitor the flue gas outlet using safety devices (such as a flue gas thermostat)
Simultaneous operation
An approved safety system (such as an air pressure monitor) ensures that during
simultaneous operation of the boiler and the air-drawing appliance the pressure
conditions are maintained. In the event of a fault, the safety system will switch off one of
the air-drawing systems.
Alternating operation
An approved safety system (such as a flue gas thermostat) ensures (e.g. by switching off
the power supply) that the boiler cannot be operated simultaneously with the air-drawing
appliance.

3 | Design Information
14 M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
3.6 Domestic hot water
Unless contrary to other national regulations, the latest versions of the following
standards and guidelines apply:
Austria:
Germany:
ÖNORM H 5195
VDI 2035
Switzerland:
Italy:
SWKI BT 102-01
UNI 8065
Observe the standards and also follow the recommendations below:
rAim for a pH value of between 8.2 and 10.0. If the central heating water comes into
contact with aluminium, the pH value must be between 8.0 and 8.5
rUse prepared water which complies with the standards cited above for filling and
make-up water
rAvoid leaks and use a closed heating system to maintain water quality during
operation
rWhen filling with make-up water, always bleed the filling hose before connecting, in
order to prevent air from entering the system
Advantages of prepared water:
▪ Complies with the applicable standards
▪ Less of a drop in output due to reduced limescale build-up
▪ Less corrosion due to fewer aggressive substances
▪ Long-term cost savings thanks to improved energy efficiency
Permitted water hardness for the fill and make-up water in accordance with VDI
2035:
Overall
heat output
Total hardness at
<20 l/kW minimum
individual heat output 1)
Total hardness at
>20 ≤50 l/kW minimum
individual heat output 1)
Total hardness at
>50 l/kW minimum
individual heat output 1)
kW °dH mol/m³ °dH mol/m³ °dH mol/m³
≤50 no demand or 11.2 2 0.11 0.02
<16.8 2) <3 2)
>50 ≤200 11.2 2 8.4 1.5
>200 ≤600 8.4 1.5 0.11 0.02
>600 0.11 0.02
1. From specific system volume (litres nominal capacity/heat output; for multi-boiler systems use the smallest individual heat output)
2. In the case of systems with central heating boilers and for systems with electric heating elements

Design Information | 3
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact 15
Additional requirements for Switzerland
The filling and make-up water must be demineralised (fully purified)
▪ The water must not contain any ingredients that could settle and accumulate in the system
▪ This makes the water non-electroconductive, which prevents corrosion
▪ It also removes all the neutral salts such as chloride, sulphate and nitrate which can weaken
corrosive materials in certain conditions
If some of the system water is lost, e.g. during repairs, the make-up water must also be
demineralised. It is not enough to soften the water. The heating system must be professionally
cleaned and rinsed before filling the units.
Inspection:
▪ After eight weeks, the pH value of the water must be between 8.2 and 10.0. If the central
heating water comes into contact with aluminium, the pH value must be between 8.0 and 8.5
▪ Yearly. Values must be recorded by the owner
3.7 Pressure maintenance systems
Pressure maintenance systems in hot-water heating systems keep the required pressure
within predefined limits and balance out volume variations caused by changes in the hot-
water temperature. Two main systems are used:
Compressor-controlled pressure maintenance
In compressor-controlled pressure maintenance units, a variable air cushion in the
expansion tank is responsible for volume compensation and pressure maintenance. If the
pressure is too low, the compressor pumps air into the tank. If the pressure is too high, air
is released by means of a solenoid valve. The systems are built solely with closed-
diaphragm expansion tanks to prevent the damaging introduction of oxygen into the
heating water.
Pump-controlled pressure maintenance
A pump-controlled pressure maintenance unit essentially consists of a pressure-
maintenance pump, relief valve and an unpressurised receiving tank. The valve releases
hot water into the receiving tank if the pressure is too high. If the pressure drops below a
preset value, the pump draws water from the receiving tank and feeds it back into the
heating system. Pump-controlled pressure maintenance systems with open expansion
tanks (e.g. without a diaphragm) introduce ambient oxygen via the surface of the water,
exposing the connected system components to the risk of corrosion. These systems offer
no oxygen removal for the purposes of corrosion control as required by VDI 2035 and in
the interests of corrosion protection should not be used.

3 | Design Information
16 M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
3.8 Storage tank
Observe the regional regulations for using a storage tank!
Certain subsidy guidelines prescribe compulsory requirements for the installation of
storage tanks. Up-to-date information about individual subsidy guidelines can be found at
www.froeling.com.
Channelling the heat generated by the Dual fuel boiler to a storage tank can bring major
advantages, such as
▪ better utilisation of fuel
▪ more user-friendly operation in terms of reloading intervals
▪ maximum independence from instantaneous heating requirements
▪ minimal dirt in boiler and flue gas system
As the boiler’s minimum continuous heat output is 30% above the nominal heat output,
we as boiler manufacturer are obliged under EN 303-5:2012, Section 4.4.6 to advise that
the Dual fuel boiler SP Dual compact must always be connected to a storage tank with
adequate storage capacity.
Certain countries have recommended storage capacities; these are listed below. The
specified values apply when the nominal heat output of the boiler corresponds to the
heating requirements of the building and a maximum of 50% of the nominal heat output
can be dissipated to the building being heated under partial load conditions.
The storage tank capacity can be calculated according to EN 303-5:2012 using the
following formula:
VSp= 15TBx QN(1 - 0.3 x QH/Qmin)
VSp
QN
TB
QH
Qmin
Storage tank capacity in [l]
Nominal heat output of boiler in [kW]
Burn-off period of boiler in [h]1)
Heating load of building in [kW]
Minimum heat output of boiler in [kW] 2)
1. Sample combustion times for various fuels are provided in the technical data
2. The boiler’s minimum output is the lowest value of the output range in the technical data. If there is no minimum heat output specified, use the
nominal heat output (Qmin = QN)
For the correct dimensions of the storage tank and the line insulation (for instance to
ÖNORM M 7510 or guideline UZ37) please consult your installer or Fröling.
Recommended storage tank capacity:
Unit SP Dual compact 15 SP Dual compact 20
Recommended storage tank capacity1) [l] 1000 1250
1. Values for calculating the capacity can be found in the technical data or the technical data with partial load inspection (if available)
The exact design of the storage tank capacity is in accordance with the locally applicable
guidelines and regulations:
Austria According to the relevant Austrian laws governing energy technology, which are based on
Art. 15aB-VG "Agreement on protective measures for small furnaces" (2012):
No storage tank is required on manually fed biomass boilers that have been positively
tested at both nominal load and partial load (below 50% of nominal load) to ensure they
adhere to the emissions limits specified in that agreement.

Design Information | 3
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact 17
Germany The first BImSchV (Ordinance on small and medium-sized heating plants of 26 January
2010, BGBl. I P. 38) stipulates a minimum water heat storage tank volume of 55 litres per
kilowatt of rated heat output; a water heat storage tank with a volume of 12 litres per litre
of fuel loading chamber is recommended.
Switzerland In accordance with the Swiss Federal Ordinance on Air Pollution Control (LRV 2018),
appendix 3, paragraph 523 “Special requirements for boilers”, hand-fed boilers up to 500
kW rated heat output must be fitted with a minimum heat storage tank volume of 12 litres
per litre of fuel loading chamber. The volume may not fall below 55 litres per kW rated
heat output.
3.9 Return lift
If the hot water return is below the minimum return temperature, some of the hot water
outfeed will be mixed in.
CAUTION
Risk of dropping below dew point/condensation formation if operated without return
temperature control.
Condensation water forms an aggressive condensate when combined with
combustion residue, leading to damage to the boiler.
Take the following precautions:
rRegulations stipulate the use of a return temperature control.
ÄThe minimum return temperature is 60 °C. We recommend fitting some sort of
control device (e.g. thermometer).
3.10 Boiler ventilation
rFit the automatic ventilating valve at the highest point on the boiler or at the ventilation
connection (if present).
ÄThis ensures that air in the boiler is constantly expelled, thus preventing
malfunctions caused by air in the boiler
rCheck that the boiler ventilation is working properly
ÄAfter installation and periodically according to manufacturer’s instructions
Tip: rFit a vertical pipe as a calming section in front of the automatic ventilating valve in
such a way that the ventilating valve is positioned above the water level in the boiler
Recommendation: rFit a microbubble separator in the pipes to the boiler
ÄFollow the manufacturer's instructions!

4 | Technical information
18 M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
4 Technical information
4.1 Dimensions SP Dual compact
H1
H3
H8
H2
H6
H7
H5H4
B2 B3
B4
B5
B8
B9
B10
B6 B7
B1
L2
L3
L1
Dimensi
on
Description Unit 15-20
L1 Length, pellet unit mm 855
L2 Length, firewood boiler 1000
L3 Total length incl. induced draught fan 1080
B1 Total width including WOS lever 1145
B2 Width, firewood boiler 685
B3 Width, pellet unit 315
B4 SP Dual width 1000
B5 Distance between flue gas pipe connection and side of boiler 665
B6 Distance between safety heat exchanger connection and side of boiler 430
B7 Distance between safety heat exchanger connections 65
B8 Distance between flow connection and side of boiler 570
B9 Distance between return connection and side of boiler 150
B10 Distance between drainage connection and side of boiler 890
H1 Height, pellet unit 1340
H2 Height of flue gas pipe connection1) 1300
H3 Total height incl. flue gas nozzle 1395
H4 Height of hose line connection 1255
H5 Height, safety heat exchanger connection 1040
H6 Height, drainage connection 150
H7 Height, flow connection 1055
1. When using the optional flue pipe nozzle for low chimney connections

Technical information | 4
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact 19
4.2 Components and connections
1
23
4
5
6
78
9
10
Item Description SP Dual compact 15-20
1Boiler flow connection 1” IT
2Boiler return connection 1” IT
3Drainage connection 1/2“ IT
4Safety heat exchanger connection 1/2“ IT
5Immersion sleeve sensor connection for thermal discharge valve (installed by the
customer)
1/2“ IT
6Flue gas pipe connection (external diameter) 129 mm
7Position for boiler sensor and STL capillary (internal diameter) 16 mm
8Position for Lambda probe 3/4" IT
9Position for flue gas temperature sensor 1/2“ IT
10 Pipe union 1) - Pellet unit outfeed to firewood boiler return 1“
1. Included in delivery

4 | Technical information
20 M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
4.3 Technical specifications
4.3.1 SP Dual compact 15/20
Technical specifications of the firewood boiler
Refer to the relevant assembly instructions for technical specifications and information
regarding efficiency and emissions in firewood operation.
Technical specifications of the pellet unit
Description SP Dual compact
15 20
Nominal output kW 15 20
Output range - pellet operation kW 4,4-15,0 4,4-20,0
Electrical connection 230V / 50Hz / fused C16A
Power consumption in pellet mode W 37-56 37-63
Power consumption in slumber mode 3
Boiler weight incl. pellet unit kg 645 655
Weight of pellet unit 190
Total boiler capacity (water) l 105
Pellet container capacity 40
Water pressure drop
(ΔT = 10 / 20K)
mbar 4.5
At least boiler return temperature °C 60
Max. permitted operating temperature °C 90
Permitted operating pressure bar 3
Boiler class as per EN 303-5:2012 5
Permitted fuel as per EN ISO 17225 Part 2: Wood pellets class A1 / D06
Airborne sound level dB(A) <70
Test book number PB 082 PB 083
Regulation (EU) 2015/1187 SP Dual compact
15 20
Energy efficiency class of boiler A+ A+
Energy efficiency index (EEI) of boiler 118 118
Heating space annual rate of use ηs % 80 80
Energy efficiency index (EEI) of boiler and controller combined 120 120
Energy efficiency class of boiler and controller combined A+ A+