STIEBEL ELTRON WPL 08 S Trend Instruction Manual

OPERATION AND INSTALLATION
Air source heat pump
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CONTENTS
SPECIAL INFORMATION
OPERATION
1. General information �����������������������������������������3
1.1 Relevant documents_____________________________________________ 3
1.2 Safety instructions_______________________________________________ 3
1.3 Other symbols in this documentation _______________________ 4
1.4 Units of measurement __________________________________________ 4
1.5 Standardised output data ______________________________________ 4
2. Safety����������������������������������������������������������4
2.1 Intended use______________________________________________________ 4
2.2 General safety instructions ____________________________________ 4
3. Appliance description ���������������������������������������5
3.1 Function ___________________________________________________________ 5
4. Cleaning, maintenance and care ���������������������������6
5. Troubleshooting ����������������������������������������������6
INSTALLATION
6. Safety����������������������������������������������������������7
6.1 General safety instructions ____________________________________ 7
6.2 Instructions, standards and regulations ____________________ 7
7. Appliance description ���������������������������������������7
7.1 Standard delivery________________________________________________ 7
7.2 Accessories________________________________________________________ 7
8. Preparations ��������������������������������������������������8
8.1 Sound emissions_________________________________________________ 8
8.2 Minimum clearances____________________________________________ 8
8.3 Preparation of the installation site___________________________ 9
8.4 Installing supply lines__________________________________________ 10
8.5 Heat pump manager ___________________________________________ 10
8.6 Buffer cylinder __________________________________________________ 10
8.7 Preparing the electrical installation ________________________ 10
9. Installation�������������������������������������������������� 11
9.1 Transport and storage _________________________________________ 11
9.2 Installation notes _______________________________________________ 11
9.3 Heating water connection_____________________________________ 11
9.4 Oxygen diffusion________________________________________________ 12
9.5 Filling the heating system ____________________________________ 12
9.6 Minimum flow rate _____________________________________________ 12
9.7 Setting the flow rate on the heating side __________________ 12
9.8 Condensate drain _______________________________________________ 14
9.9 Power supply ____________________________________________________ 14
9.10 Fitting the side panels and appliance cover_______________ 16
9.11 Ribbon heater ___________________________________________________ 18
10. Commissioning ��������������������������������������������� 19
10.1 Checks before commissioning________________________________ 19
10.2 Settings ___________________________________________________________ 19
10.3 Appliance handover ____________________________________________ 20
10.4 Recommissioning _______________________________________________ 20
10.5 Operation and control _________________________________________ 20
10.6 Shutdown ________________________________________________________ 20
11. Maintenance ������������������������������������������������ 20
11.1 Cleaning the evaporator_______________________________________ 21
11.2 Fan noise _________________________________________________________ 21
12. Specification ������������������������������������������������ 22
12.1 Dimensions and connections_________________________________ 22
12.2 Wiring diagrams ________________________________________________ 24
12.3 Operating range w/o electric emergency/booster
heater _____________________________________________________________ 26
12.4 Performance diagram WPL 08 S Trend _____________________ 26
12.5 Performance diagram WPL 12 S Trend _____________________ 27
12.6 Performance diagram WPL 16 S Trend _____________________ 27
12.7 Performance diagram WPL 22 Trend________________________ 28
12.8 Performance diagram WPL 28 Trend________________________28
12.9 Data table ________________________________________________________ 29
GUARANTEE
ENVIRONMENT AND RECYCLING

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SPECIAL INFORMATION | OPERATION
General information
SPECIAL INFORMATION
- The appliance may be used by children aged8
and older and persons with reduced physical,
sensory or mental capabilities or a lack of ex-
perience and know-how, provided that they are
supervised or they have been instructed on how
to use the appliance safely and have understood
the resulting risks. Children must never play with
the appliance. Children must never clean the ap-
pliance or perform user maintenance unless they
are supervised.
- The connection to the power supply must be in
the form of a permanent connection. Ensure the
appliance can be separated from the power sup-
ply by an isolator that disconnects all poles with
at least 3mm contact separation.
- Maintain the minimum clearances to ensure trou-
ble-free operation of the appliance and facilitate
maintenance work.
- Maintenance work, such as checking the electri-
cal safety, must only be carried out by a qualified
contractor.
- We recommend an annual inspection (to establish
the current condition of the system), and main-
tenance by a qualified contractor if required (to
return the system to its original condition).
- Following isolation from the mains supply, parts
of the appliance may remain live for up to 5min-
utes. This is because the capacitors on the invert-
er still have to discharge.
- Never interrupt the power supply, even outside
the heating period. The system‘s active frost pro-
tection is not guaranteed if the power supply is
interrupted.
- If the heat pump and frost protection are com-
pletely switched off, drain the system on the
water side.
OPERATION
1. General information
The chapters „Special Information“ and „Operation“ are intended
for both the user and qualified contractors.
The chapter „Installation“ is intended for qualified contractors.
Note
Read these instructions carefully before using the appli-
ance and retain them for future reference.
Pass on the instructions to a new user if required.
1.1 Relevant documents
Operating and installation instructions for heat pump
manager
Operating and installation instructions for attached in-
ternal unit
1.2 Safety instructions
1.2.1 Structure of safety instructions
!
KEYWORD Type of risk
Here, possible consequences are listed that may result
from failure to observe the safety instructions.
 Steps to prevent the risk are listed.
1.2.2 Symbols, type of risk
Symbol Type of risk
Injury
Electrocution
1.2.3 Keywords
KEYWORD Meaning
DANGER Failure to observe this information will result in serious
injury or death.
WARNING Failure to observe this information may result in serious
injury or death.
CAUTION Failure to observe this information may result in non-seri-
ous or minor injury.
!

OPERATION
Safety
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1.3 Other symbols in this documentation
Note
General information is identified by the adjacent symbol.
 Read these texts carefully.
Symbol Meaning
Material losses
(appliance damage, consequential losses and environmen-
tal pollution)
Appliance disposal
 This symbol indicates that you have to do something. The ac-
tion you need to take is described step by step.
1.4 Units of measurement
Note
All measurements are given in mm unless stated oth-
erwise.
1.5 Standardised output data
Explanations to determine and interpret the specified standardised
output data.
1.5.1 EN 14511
The output data specifically mentioned in text, diagrams and
technical datasheets has been calculated according to the test
conditions of the standard shown in the heading of this section.
However, there is a deviation from this norm in the output data for
air/water inverter heat pumps at source temperatures of > -7°C
as this concerns partial load values. The associated percentage
weighting in the partial load range can be found in EN14825 and
EHPA quality label regulations.
Generally, the test conditions stated above will not fully meet the
conditions found at the installation site of the system user.
Depending on the chosen test method and the extent to which
this method deviates from the test conditions defined in the first
paragraph of this section, any deviations can have a considerable
impact.
Further factors that have an influence on the test values are the
measuring equipment, the system configuration, the age of the
system and the flow rates.
A confirmation of the specified output data can only be obtained
if the test conducted for this purpose is also performed in ac-
cordance with the test conditions defined in the first paragraph
of this section.
2. Safety
2.1 Intended use
This appliance may only be installed in sealed hot water heating
systems in accordance with EN12828.
This appliance is intended for domestic use. It can be used safely
by untrained persons. The appliance can also be used in a non-do-
mestic environment, e.g. in a small business, as long as it is used
in the same way.
Any other use beyond that described shall be deemed inappropri-
ate. Observation of these instructions and of instructions for any
accessories used is also part of the correct use of this appliance.
2.2 General safety instructions
!
WARNING Injury
The appliance may be used by children aged 8 and older
and persons with reduced physical, sensory or mental
capabilities or a lack of experience and know-how, pro-
vided that they are supervised or they have been in-
structed on how to use the appliance safely and have
understood the resulting risks. Children must never play
with the appliance. Children must never clean the ap-
pliance or perform user maintenance unless they are
supervised.
!
WARNING Injury
 For safety reasons, only operate the appliance with
the casing closed.
Observe the following safety instructions and regulations.
- Only qualified contractors may carry out the electrical work
and installation of this appliance.
- The qualified contractor is responsible for adherence to all
currently applicable instructions during installation and
commissioning.
- Operate the appliance only when fully installed and with all
safety equipment fitted.
- Protect the appliance from dust and dirt ingress during
building work.
!

OPERATION
Appliance description
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3. Appliance description
This appliance is a heat pump designed for outdoor installation.
This appliance is used to connect an internal unit (see the chapter
„Accessories/ Required accessories“).
This appliance functions as an air source heat pump. Heat is ex-
tracted from the outdoor air at a low temperature level, and is
then transferred to the heating water at a higher temperature.
Depending on the outside temperature, the heating water can
be heated to a flow temperature of up to 62°C (see the chapter
„Specification/ Operating range w/o electric emergency/booster
heater“).
3.1 Function
3.1.1 Heating
Heat is extracted from the outdoor air via the heat exchanger
(evaporator) on the air side. The evaporated refrigerant is com-
pressed in a compressor. This process requires electrical energy.
This process brings the refrigerant to a higher temperature level.
A further heat exchanger (condenser) transfers the heat to the
heating circuit. During this process, the refrigerant expands, and
the cycle starts from the beginning.
This appliance‘s operating principle is based on demand-depend-
ent control of the compressor output with the addition of an elec-
tric emergency/booster heater fitted inside the internal unit. The
heat pump manager controls the heat pump subject to the preset
heating curve.
Note
For centralised control of the heating system you will
need the WPM heat pump manager.
If the heat pump cannot cover the heating and hot water demand
of the home, the internal unit automatically starts the electric
emergency/booster heater. This operates together with the heat
pump to generate the required flow temperature.
Operation when the heat pump is disabled
The heat pump automatically shuts down at outdoor temperatures
below –20°C. In this case, the indoor unit‘s electric emergency/
booster heater automatically takes over central heating and DHW
heating. The heat pump automatically shuts down at outside tem-
peratures above +35°C.
When the outside temperature rises above -17°C or falls below
+32°C, the heat pump starts up again.
3.1.2 Automatic defrosting
Defrosting takes different forms depending on the prevailing am-
bient conditions:
During operation
At outdoor temperatures above +5°C, the heat pump fan oper-
ates at maximum speed, while the compressor speed is restricted
until the end of the defrosting process. Heating continues during
defrosting.
By circulation reversal
!
Material losses
In the defrost cycle, the fan is switched off and the heat
pump circuit is reversed. The heat required for defrosting
is drawn from the buffer cylinder. For operation without a
buffer cylinder, observe chapter "Operation / Menu struc-
ture / Menu SETTINGS/ STANDARD SETTING/ BUFFER
OPERATION" in the operating and installation instructions
of the WPM. This prevents damage to the heat pump as
a result of unfavourable conditions.
At outdoor temperatures below +5°C, the flow direction in the re-
frigerant circuit is reversed via a 4/2-way diverter valve. Defrosting
is achieved by routing the compressed gas from the compressor
into the evaporator. During this process, the heating system cools
down slightly. The duration of the defrosting process depends on
the thickness of the ice, the system temperature and the prevailing
outside temperature.
3.1.3 Cooling
!
Material losses
The heat pump is not suitable for continuous, year-round
cooling.
 Observe the application limits (see chapter "Specifi-
cation/ Data table").
Rooms are cooled by reversing the heat pump circuit. Heat is
extracted from the heating water and the evaporator transfers
this heat to the outdoor air.
Area cooling requires the installation of the FEK remote control
unit in a reference room to capture the relative humidity and the
room temperature as part of monitoring the dew point.
Heat pump application limit
The heat pump is switched off if the outside temperature falls
below the selected lower application limit for cooling (parameter
LIMITCOOLING).
In cooling mode the heat pump shuts down if the outside tem-
perature rises above +45°C. When the outside temperature falls
below +42°C, the heat pump starts up again.

OPERATION
Cleaning, maintenance and care
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4. Cleaning, maintenance and care
!
Material losses
Only qualified contractors may perform maintenance
work, such as electrical safety checks.
- A damp cloth is sufficient for cleaning all plastic and sheet
metal parts. Never use abrasive or corrosive cleaning agents.
- Check the condensate drain monthly (visual inspection).
Remove any contamination and blockages (see the chapter
„Installation/ Condensate drain“).
- Keep the air discharge and intake apertures free from snow
and leaves.
- We recommend an annual inspection (to establish the cur-
rent condition of the system), and maintenance by a qualified
contractor if required (to return the system to its original
condition).
- Protect the appliance from dust and dirt ingress during
building work.
5. Troubleshooting
Fault Cause Remedy
There is no hot
water or the
heating system
stays cold.
No power at the appliance. Check the fuses/MCBs in
your fuse box/distribution
panel. Replace the fuses/
reset the MCBs if required.
Notify your qualified con-
tractor if the fuses/MCBs
blow/trip again.
Water is leaking
from the appli-
ance.
The condensate drain may be
blocked.
Clean the condensate drain
as described in "Mainte-
nance and care"
Condensate
collects on the
outside of the
appliance and on
the air grille.
The heat pump is drawing heat
from the outdoor air to heat
the building. This can cause
the humidity in the outdoor air
to accumulate as dew or frost
on the cooled heat pump cas-
ing. This is not a defect.
Note
Even when the condensate is draining away correctly,
expect water to drip from the appliance onto the floor.
If you cannot remedy the fault, notify your contractor. To facilitate
and speed up your request, provide the number from the type
plate (000000-0000-000000).

INSTALLATION
Safety
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INSTALLATION
6. Safety
Only a qualified contractor should carry out installation, commis-
sioning, maintenance and repair of the appliance.
6.1 General safety instructions
We guarantee the trouble-free function and operational reliabil-
ity only if original accessories and spare parts intended for the
appliance are used.
6.2 Instructions, standards and regulations
Note
Observe all applicable national and regional regulations
and instructions.
7. Appliance description
D0000052380
1
654
3
2
1 Electronic expansion valve VR0
2 Electronic expansion valve VR1
3 4-way valve
4 Pressure switch/ pressure sensor
5 Compressor
6 Inverter
7.1 Standard delivery
The following are delivered with the appliance:
- 4 adjustable feet
- 1 appliance cover
- 2 side panels
- 1 front panel
- 8 screws
- 4 washers
- 1 adaptor for return sensor
7.2 Accessories
7.2.1 Required accessories
- Internal unit (hydraulics module, cylinder and hydraulics
module or integral cylinder)
- Pressure hoses
7.2.2 Further accessories
- FEK remote control
- FE7 remote control
- Ribbon heater HZB-1
- Ribbon heater HZB-2
- Water softener HZEA
- Evaporator contact protection BSV 08-16
- Evaporator contact protection BVS 22-28

INSTALLATION
Preparations
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8. Preparations
!
D0000060163
The appliance is designed for siting in front of a wall. Observe the
minimum clearances. If the appliance is installed in an open space
or on a roof, protect the air intake side. Do this by erecting a wall
to shield it against the wind.
8.1 Sound emissions
Note
For details regarding the sound power level, see the
chapter "Specification/ Data table".
Observe the following information when selecting the installation
site.
- Ensure that the air is drawn in with the wind and expelled
parallel to the main wind direction (see chapter “Preparation
of the installation site / foundations”).
- The appliance generates operating noise.
- The operating noise is louder on the air intake and air dis-
charge sides than on the two enclosed sides.
- Never install the appliance in noise-sensitive rooms. Never
direct the air intake or discharge towards noise-sensitive
rooms of the house, such as bedrooms.
- Installation in corners of buildings or areas surrounded by
walls can result in an elevated noise level. Never install the
appliance in recesses that are surrounded by three walls.
- Reflecting building walls can increase the noise level. Never
install the appliance between reflecting building walls.
- Never install the appliance on large, echoing floor areas,
such as tiled floors.
- Thick palisading and/or lawns and plantings can reduce the
sound propagation.
- Maintain the minimum clearances.
8.2 Minimum clearances
 Maintain the minimum clearances to ensure trouble-free op-
eration of the appliance and facilitate maintenance work.
WPL 08S Trend | WPL 12S Trend | WPL 16S Trend
≥2000
≥400
≥500
≥1000 ≥1000
D0000052367
WPL 22 Trend | WPL 28 Trend
≥2000
≥400
≥600
≥1000 ≥1000
D0000052368

INSTALLATION
Preparations
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91_00_00_0036
Note
Installation in corners of buildings or areas surround-
ed by walls can lead to elevated noise levels and severe
evaporator contamination.
 Never install the appliance in a recess. Two sides of
the appliance must remain exposed.
8.3 Preparation of the installation site
8.3.1 General information
- Follow the instructions in the chapter „Preparations/ Sound
emissions“.
- Ensure that the appliance is accessible from all sides.
- The substrate must be horizontal, level, solid and permanent.
- If you wish to route the supply lines below ground, check the
foundation layout to determine whether a corresponding re-
cess in the foundation will be necessary.
8.3.2 Foundation
Example: Foundation slab
B
A
1
3
2
D0000061048
1 Air intake side
2 Air discharge side
3 Main wind direction
Heat pump A B
WPL 08S Trend | WPL 12S Trend | WPL 16S Trend 1000 650
WPL 22 Trend | WPL 28 Trend 1200 720
Example: Strip foundation
B
A
1
3
2150150
D0000061049
1 Air intake side
2 Air discharge side
3 Main wind direction
Heat pump A B
WPL 08S Trend | WPL 12S Trend | WPL 16S Trend 510 650
WPL 22 Trend | WPL 28 Trend 680 720
Example: Laying pipes below ground
5
6
A
B
2
4
3
1
D0000052374
A 300mm
B Depth of frost line
1 Heating flow
2 Heating return
3 Condensate drain 40mm
4 Condensate drain pipe
5 Concrete foundations
6 Gravel bed

INSTALLATION
Preparations
10 | WPL 08-28 (S) Trend www.stiebel-eltron.com
8.4 Installing supply lines
The supply lines include all cables plus the heating flow and re-
turn lines.
- Use only weatherproof cables, e.g. NYY.
- Protect the flow and return lines against frost with sufficient
thermal insulation. Provide thermal insulation in accordance
with applicable regulations.
- Also protect all supply lines/cables against humidity, damage
and UV radiation (if applicable) by means of a conduit.
- Protect all pipe fixings and external wall ducts with anti-vi-
bration insulation.
8.5 Heat pump manager
A WPM heat pump manager is required to operate the appliance.
This controls the entire heating system.
8.6 Buffer cylinder
A buffer cylinder is recommended to ensure trouble-free appliance
operation.
The buffer cylinder provides hydraulic separation of the volume
flows in the heat pump circuit and heating circuit, and also serves
as an energy source for defrosting.
 When operating without a buffer cylinder, observe the de-
tails specified in chapter „Minimum flow rate with individual
room controller by means of FEK / FE7 in the case of systems
without buffer cylinder“.
!
Material losses
A buffer cylinder with diffusion-proof insulation is es-
sential for cooling mode. The emergency/booster heater
must be connected.
8.7 Preparing the electrical installation
WARNING Electrocution
Carry out all electrical connection and installation work
in accordance with national and regional regulations.
WARNING Electrocution
The connection to the power supply must be in the form
of a permanent connection. Ensure the appliance can
be separated from the power supply by an isolator that
disconnects omnipolar with at least 3mm contact sepa-
ration. This requirement can be met by contactors, iso-
lators, fuses, etc.
!
Material losses
The specified voltage must match the mains voltage. Ob-
serve the type plate.
!
Material losses
Provide separate fuses for the three power circuits (appli-
ance, electric emergency/booster heater, control).
 Lay the relevant pipe cross-sections. Observe the applicable
national and regional regulations.
MCB/fuse
rating
Assignment Cable cross-section
1x C 16 A Compressor
(single phase)
WPL 08 S Trend
WPL 12 S Trend
WPL 16 S Trend
2.5 mm² for routing above the surface
4.0 mm² for routing through a wall
3x C 16 A Compressor
(3-phase)
WPL 22 Trend
WPL 28 Trend
2.5 mm²
1.5 mm² with only two live cores and routing
on a wall or in an electrical conduit on a
wall.
1x B 16 A Control 1.5 mm²
Note
The fuse/MCB for the 3 phase compressor must blow/
respond across all poles.
The electrical data is provided in the chapter „Specification“ . You
will need a J-Y (St) 2x2x0.8mm² cable for the CAN BUS.
Note
The appliance includes an inverter for the variable speed
compressor. In case of a fault inverters can cause DC
residual currents. If RCDs are provided, they have to be
type B AC/DC-sensitive.
A DC residual current can block type A RCDs.
 Make sure that the appliance power supply is dis-
connected from the fuse board/distribution panel.

INSTALLATION
Installation
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9. Installation
9.1 Transport and storage
!
Material losses
Protect the appliance against strong vibrations during
transport.
- Transport and store the appliance only in an upright position.
- Allow the appliance to be tipped only temporarily and only
on the long side (max.45°). Tipping the appliance distrib-
utes the refrigerant oil in the system. Wait approx. 30min-
utes before operating the appliance after it has been tipped.
- Never store the appliance at temperatures below –20°C.
- Carry the appliance using the strap handles.
9.2 Installation notes
!
Material losses
Install the appliance in a location where no snow or water
can drip or fall on it from the roof.
When installing a protective roof above the appliance,
make sure to leave enough space above the appliance
to lift and remove the insulating material from the top.
Minimum clearances:
- WPL 08 S Trend | WPL 12 S Trend | WPL 16 S Trend:
500mm
- WPL 22 Trend | WPL 28 Trend: 600mm
- With removable protective roof (all appliance types):
400mm
- Position the appliance on a flat stable surface.
- When installing the appliance in an open space or on a roof,
protect the air intake. Do this by erecting a wall to shield it
against the wind.
- Air should not be blown out against the wind. Ensure that
the air intake direction is the same as the dominant wind
direction.
- Position the appliance to ensure that air can flow through the
evaporator freely. Observe the minimum clearances.
- Position the appliance so as to prevent cold air recirculation.,
9.2.1 Anchoring the appliance
!
WARNING Injury
The appliance may tip over if not securely anchored.
 Anchor the adjustable feet to the sub-base using
appropriate fastening materials.
D0000052377
9.3 Heating water connection
The heat pump heating system must be connected by a qualified
contractor in accordance with the water installation drawings,
which are part of the technical guides.
!
Material losses
Residue and particles (e.g. weld beads, rust, sand, gasket
material) in the heating system will obstruct the flow and
lead to malfunctions. Contamination in the lines will block
the heat pump condenser.
 To remove residue, thoroughly flush the pipework
before connecting the heat pump.
 Connect the heat pump on the heating water side. Check for
tightness.
 Ensure the heating flow and return are connected correctly
(see the chapter „Flow and return connection“).
 Provide thermal insulation in accordance with applicable
regulations.
 When designing the heating circuit, observe the internal
pressure differential (see the chapter „Specification/ Data
table“).

INSTALLATION
Installation
12 | WPL 08-28 (S) Trend www.stiebel-eltron.com
9.3.1 Flow and return connection
!
Material losses
 Insulate the heating flow and return lines with va-
pour diffusion-proof material.
D0000064755
1
2
1 Heating flow
2 Heating return
 Connect the flexible pressure hoses to the flow and return
line connectors.
 Insert the immersion sensor into the “heating return”.
Structure-borne noise is largely prevented by the anti-vibration
construction of the heat pump and by the flexible pressure hoses,
which act as anti-vibration mounts.
9.4 Oxygen diffusion
!
Material losses
Avoid open heating systems and plastic pipes in under-
floor heating systems which are permeable to oxygen.
In underfloor heating systems with plastic pipes that are per-
meable to oxygen and in open vented heating systems, oxygen
diffusion may lead to corrosion on the steel components of the
heating system (e.g.on the indirect coil of the DHW cylinder, on
buffer cylinders, steel heating elements or steel pipes).
 With heating systems that are permeable to oxygen, discon-
nect the heating system between the heating circuit and the
buffer cylinder.
!
Material losses
The products of corrosion (e.g.rusty sludge) can settle in
the heating system components and can result in a lower
output or fault shutdowns due to reduced cross-sections.
9.5 Filling the heating system
 Fill the heating system via the drain on the system side.
9.5.1 Water quality
A fill water analysis must be carried out before the heating system
is filled. The fill water analysis may, for example, be requested
from the relevant water supply utility.
- For heating systems that must be topped up regularly or in
cases where the fill water is determined to be contaminated
when sampled, take the necessary action, e.g. installing a
filter and aerator, prior to installing the heat pump.
- To avoid damage as a result of scaling, process the fill water
by softening or desalinating it.
- Observe the limits concerning fill water (see the chapter
„Specification/ Data table“).
- Recheck these limits 8-12 weeks after commissioning and
during the annual system service.
Note
Water desalination is recommended at a conductivity of
>1000μS/cm.
Note
If you treat the fill water with inhibitors or additives, the
same limits as for desalination apply.
Note
Suitable appliances for water softening, as well as for
filling and flushing heating systems, can be obtained from
trade suppliers.
9.6 Minimum flow rate
For heating operation without a buffer cylinder, always ensure the
minimum flow rate and the availability of energy for defrosting.
9.7 Setting the flow rate on the heating side
!
Material losses
For operation without a buffer cylinder, it is essential
that the electric emergency/booster heater (DHC) is con-
nected.
The appliance is designed in such a way that no buffer cylinder
is required in conjunction with appropriately sized area heating
systems.
We recommend the use of a buffer cylinder for installations with
several heating circuits.
The flow rate is set in heat pump mode. For this, make the fol-
lowing settings first:
 Temporarily remove the fuse from the electric emergency/
booster heater to isolate the emergency/booster heater from
the power supply. Alternatively, switch OFF the second heat
generator.
 Operate the appliance in heating mode.

INSTALLATION
Installation
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9.7.1 Minimum flow rate with individual room controller by
means of FEK / FE7 in systems without buffer cylinder
For systems without a buffer cylinder, in menu „SETTINGS/ HEAT-
ING/ STANDARD SETTING“, set parameter „BUFFER OPERATION“
to „OFF“.
In such cases, one or more heating circuits in the heating system
must be left open. Ensure the minimum flow rate (see „Specifica-
tion / Data table“) by means of the correspondingly opened heat-
ing circuits (see table „Design recommendation for an underfloor
heating system inside the lead room“).
Design recommendation for underfloor heating system inside the
lead room:
Minimum flow
rate
Minimum water content of buffer
cylinder or open circuits
Composite pipework 16 x 2mm
/ routing gap 10cm
Composite pipework 20x2.25mm /
routing gap 15cm
Lead room
floor area
Number of cir-
cuits
Lead room
floor area
Number of cir-
cuits
l/h lm² n x m m² n x m
WPL 08 S Trend 830 32 32 4x80 27 2x90
WPL 12 S Trend 1190 36 - - 32 3x70
WPL 16 S Trend 1550 45 - - - -
WPL 22 Trend 2230 54 - - - -
WPL 28 Trend 2500 67 - - - -
Buffer cylinder always
required
Recommended buffer cylinder
volume, underfloor heating
Recommended buffer cylinder
volume, radiators
Activating the integral
emergency/booster
heater
WPL 08 S Trend no 100 200 yes
WPL 12 S Trend no 200 400 yes
WPL 16 S Trend yes 200 400 yes
WPL 22 Trend yes 200 400 yes
WPL 28 Trend yes 200 400 yes
 Install the open heating circuit(s) in the lead room (room
where the external programming unit of the heat pump
control unit is installed, such as in the living room). The indi-
vidual room can then be controlled either with the external
programming unit or directly by adjusting the heating curve
or the room influence.
The flow rate is set automatically via the self-regulating system
(see menu “COMMISSIONING / HEATING / SPREAD CONTROL /
STANDBY PUMP RATE” in the heat pump manager).
In heat pump mode a fixed spread between the heat pump flow
and return is set (see menu “COMMISSIONING / HEATING / SPREAD
CONTROL” in the heat pump manager).
The current flow rate can be called up in the menu „INFO/ HEAT
PUMP INFO/ PROCESS DATA“ under „WP WATER FLOW RATE“.
9.7.2 Minimum flow rate for systems with buffer cylinder
When using a buffer cylinder, in menu „SETTINGS/ HEATING/
STANDARD SETTING“, set parameter „BUFFER OPERATION“ to
„ON“.
The flow rate is set automatically via the self-regulating system
(see menu “COMMISSIONING / HEATING / SPREAD CONTROL /
STANDBY PUMP RATE” in the heat pump manager).
The current flow rate can be called up in the menu „INFO/ HEAT
PUMP INFO/ PROCESS DATA“ under „WP WATER FLOW RATE“.

INSTALLATION
Installation
14 | WPL 08-28 (S) Trend www.stiebel-eltron.com
9.8 Condensate drain
A condensate drain connector is factory fitted to the defrost pan
to enable any condensate to drain off.
D0000052378
1
1 Condensate drain
 If the appliance is mounted on a wall bracket or T-support,
attach a condensate drain hose or condensate drain pipe to
the condensate drain.
 Protect the condensate drain hose/condensate drain pipe
from frost with sufficient thermal insulation.
If the condensate drain hose/condensate drain pipe is not
laid with frost protection or is exposed to severe weather
conditions, installation of a ribbon heater is recommended
(see the chapter „Ribbon heater“).
 After routing the condensate drain hose/condensate drain
pipe, check to ensure the condensate can drain correctly.
!
Material losses
Ensure the condensate drain hose is not kinked.
Place the condensate drain hose or condensate drain pipe
with a fall.
9.9 Power supply
WARNING Electrocution
Before working on the appliance, isolate it from the
power supply at the control panel.
Note
Observe the operating and installation instructions of the
WPM heat pump manager.
- Follow the instructions in the chapter „Preparations/ Prepar-
ing the electrical installation“.
- Connection work must only be carried out by a qualified con-
tractor and in accordance with these instructions.
- Permission to connect the appliance may need to be obtained
from your local power supply utility.
- The terminals are located in the wiring chamber of the
appliance.
- For all connections, use appropriate cables in accordance
with local regulations.
Access to the wiring chamber
The wiring chamber is located near the right side panel.
D0000052381
1
1 Wiring chamber
The cable entries for CAN BUS and power cable (compressor)
are located in the wiring chamber and on the back of the unit,
respectively.

INSTALLATION
Installation
www.stiebel-eltron.com WPL 08-28 (S) Trend | 15
D0000052378
1
23
1 Power cable (compressor) entry
2 Control cable entry
3 CAN BUS cable entry
For complete access to the wiring chamber of the appliance...
 Remove the appliance front panel.
 Undo the Velcro strap on the wiring chamber.
 Remove the wiring chamber cover.
Terminal assignment
1
2
3
4
5
3
4
5
A
B
N
2
N
N
1
L
N
2
N
N
1
L1
L2
L3
D0000052384
1 CAN BUS cable entry
2 Power cable (compressor) entry
control cable entry
3 Control power supply
4 Ribbon heater connection (output)
5 Compressor power supply
A Single phase heat pump
B Single phase heat pump
CAN BUS
The CAN BUS signalling cable provides the communication be-
tween the internal and external unit.
Note
High voltage lines (230/400V) in the vicinity of a commu-
nication line can cause the internal unit to malfunction.
 Route the CAN BUS separately from the power ca-
bles (separated by at least 100mm).
Common routing with sensor leads is permitted.
Note
The appliance communication circuits are not designed
for constant 12V.
 Make sure that the four cables are connected to the
correspondingly marked terminals on the circuit
board.
Note
 Remove the sheath insulation from the bus cable
either at the outdoor or indoor unit.
D0000052385
!
Material losses
The “12VDC” power supply is pre-wired at the factory.
The “gnd” terminal is therefore already assigned and
accordingly must serve as double contact when installing
the CAN BUS cable.
The “12V” terminal must not be connected directly to
the CAN BUS cable.
 Observe the wiring diagram.
The „Term.“ changeover switch marks the start and end of CAN
BUS loops. Terminate the I/O module in the heat pump (see the
chapter „Specification/ Wiring diagram for I/O module“).
9.9.1 Connecting the heat pump
 Route the power cable (compressor), the control cable, and
the CAN BUS to the wiring chamber through the correspond-
ing cable entries (see the chapter „Specification/ Dimensions
and connections“).
 Connect the power cable (compressor), the control cable, and
the CAN BUS as shown in the electrical wiring diagram (see
the chapter „Specification/ Wiring diagrams“).
 Check to ensure the cables are securely fastened and tighten
them if necessary.
 Refit the wiring chamber cover.
 Fasten the Velcro strap on the wiring chamber.

INSTALLATION
Installation
16 | WPL 08-28 (S) Trend www.stiebel-eltron.com
9.10 Fitting the side panels and appliance cover
Note
 Align the appliance before installing the side panels.
 Make sure that the appliance slope in the transverse and lengthwise directions does not exceed 1%.
Note
 Secure the side panels and appliance cover by hand.
WPL 08S Trend | WPL 12S Trend | WPL 16S Trend
3A
3B
12
7
5
6
4
D0000052386

INSTALLATION
Installation
www.stiebel-eltron.com WPL 08-28 (S) Trend | 17
WPL 22 Trend | WPL 28 Trend
1
4
5
3A
3B
6
7
2
D0000052387

INSTALLATION
Installation
18 | WPL 08-28 (S) Trend www.stiebel-eltron.com
9.11 Ribbon heater
If the condensate drain cannot be laid with frost protection or is
exposed to severe weather conditions, a ribbon heater may be
installed in the condensate drain.
D0000052381
 Uncover the appliance wiring chamber (see the chapter
„Electrical connections/ Access to the wiring chamber“).
D0000052391
 Remove the screw on the back of the unit.
 Remove the panel on the back of the unit.
D0000052392
 Push in the cover over the cable entry using a sharp object,
such as a screwdriver.
D0000052394
 Push the connection side of the heating cable through the
prepared cable entry on the back of the unit.
 Pull the heating cable through the appliance to the front.
 Route the connection end of the heating cable under the side
panel and up to the wiring chamber.
 Route the connection end of the heating cable through the
cable entry at the wiring chamber and out of the appliance.
 Connect the heating cable to the wiring chamber (see the
chapter „Electrical connection/ Terminal assignment“).
D0000052393
 Route the other end of the heating cable out of the appliance
as shown.

INSTALLATION
Commissioning
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D0000052395
 Place the heating cable in the condensate drain hose or pipe.
 Refit the appliance rear panel and the heat pump component
front panel.
10. Commissioning
A WPM heat pump manager is required to operate the appliance.
All necessary adjustments prior to and during operation are made
on this device.
Only qualified contractors or customer service associates may
perform the settings in the heat pump manager commissioning
report, perform the appliance commissioning, and instruct the
operator.
Carry out commissioning in accordance with the operating and
installation instructions of the heat pump manager.
If this appliance is intended for commercial use, observe the rules
of the relevant Health & Safety at Work Act during commissioning.
For further details, check with your local authorising body (e.g.
TÜV).
10.1 Checks before commissioning
 Before commissioning, check the following:
Heating system
- Have you filled the heating system to the correct pressure?
- Does the heating water meet the water quality requirements?
Temperature sensor
- Have you correctly positioned and connected the outside
temperature sensor and the return temperature sensor (in
connection with a buffer cylinder)?
- Has the return sensor been correctly positioned on the heat
pump?
Power supply
- Have you correctly connected the power supply?
Oil sump temperature
- When the power supply is switched on, the heat pump man-
ager checks whether the temperature differential between
the outdoor temperature and the oil sump temperature is
greater than 10 K (see “INFO / HEAT PUMP / PROCESS DATA /
OIL SUMP TEMPERATURE”). If the temperature differential is
lower, the oil sump is automatically heated up to this differ-
ential via the compressor coil.
You can call up the oil sump heater switching state in the
menu “DIAGNOSIS / HEAT PUMP STATUS / OIL SUMP”.
10.2 Settings
10.2.1 Heating curve adjustment
The efficiency of a heat pump decreases as the flow temperature
rises. The heating curve should therefore be adjusted with care.
Heating curves that are set too high cause the zone valves and
thermostatic valves to close, which may lead to the minimum flow
rate required for the heating circuit not being achieved.
 Observe the WPM operating and installation instructions.
The following steps will help you to adjust the heating curve cor-
rectly:
- Fully open thermostatic or zone valves in a lead room (e.g.
living room and bathroom).
We do not recommend installing thermostatic or zone valves
in the lead room. Control the temperature for these rooms
via remote control.
- At different outside temperatures (e.g. –10°C and +10°C),
adjust the heating curve so the required temperature is set in
the lead room.
Standard values to begin with:
Parameters Underfloor heating Radiator heating
system
Heating curve 0.4 0.8
Control response time 25 50
Comfort temperature 21°C 23°C
If the room temperature is not high enough in spring and autumn
(approx. 10 °C outside temperature), raise the „COMFORT TEM-
PERATURE“ parameter in the heat pump manager menu under
„SETTINGS / HEATING / HEATING CIRCUIT“.
Note
If no remote control is installed, raising the "COMFORT
TEMPERATURE" parameter leads to a parallel offset of
the heating curve.
Increase the „HEATING CURVE“ parameter, if the room temper-
ature is not high enough when outside temperatures are low.
If you raise the „HEATING CURVE“ parameter, adjust the zone valve
or thermostatic valve in the lead room to the required temperature
when outside temperatures are high.
!
Material losses
Never reduce the temperature in the entire building by
closing all zone or thermostatic valves, instead use the
setback programs.

INSTALLATION
Maintenance
20 | WPL 08-28 (S) Trend www.stiebel-eltron.com
When everything has been implemented correctly, the system
can be heated to its maximum operating temperature and vented
once again.
!
Material losses
With underfloor heating systems, observe the maximum
permissible temperature for the system.
10.2.2 Other settings
 For operation with and without buffer cylinder, observe
chapter „Operation / Menu structure / Menu SETTINGS/
STANDARD SETTING/ BUFFER OPERATION“ in the operating
and installation instructions of the WPM.
When using the heat-up program
If you use the heat-up program, make the following settings on
the WPM:
 Initially set parameter „DUAL MODE TEMP HZG“ to 30°C.
 Then set parameter „LOWER APP LIMIT HZG“ to 30°C.
Note
After completing the heat-up process, reset the parame-
ters "DUAL MODE TEMP HZG" and "LOWER APP LIMIT HZG"
to their respective standard values or to the respective
system values.
10.3 Appliance handover
 Explain the appliance function to users and familiarise them
with its operation.
 Make users aware of potential dangers.
 Make users aware of critical environmental factors and re-
quirements concerning the installation site.
 Hand over these operating and installation instructions to
users for safe-keeping.
10.4 Recommissioning
 Switch the power back ON.
10.5 Operation and control
!
Material losses
Never interrupt the power supply, even outside the heat-
ing season. The system's active frost protection is not
guaranteed if the power supply is interrupted.
The system does not have to be switched off in summer. The heat
pump manager has an automatic summer / winter changeover.
10.6 Shutdown
If the system is to be taken out of use, set the WPM to standby.
This retains the safety functions designed to protect the system
(e.g. frost protection).
!
Material losses
If the heat pump and frost protection are completely
switched off, drain the system on the water side.
11. Maintenance
WARNING Electrocution
The heat pump contains 'live' components. The capacitor
must be discharged after the power has been shut off.
 Isolate the system from the power supply.
 Wait at least 5 minutes before beginning any elec-
trical work.
!
WARNING Injury
The refrigerant circuit contains substances that can be
converted into toxic gases on contact with air or open
flames.
 In the event of a leak, leave the room immediately
and ensure adequate ventilation.
 Have any leaks in the refrigerant circuit repaired
immediately by a service technician or qualified re-
frigeration engineer.
!
Material losses
The electronic expansion valves are highly sensitive to
shock.
 Protect the expansion valves from impact and shock.
!
Material losses
The insulating material in the heat pump can become
deformed at excessively high temperatures.
 Remove an adequate amount of the insulating
material before performing any brazing work; use
flame-resistant protective mats if necessary.
Note
Only appropriately qualified contractors or customer
service associates may perform work on the refrigerant
circuit.
 Check the alarm history.
 Perform a function check of the internal unit as described in
the operating and installation instructions.
 Check the power cable for mechanical damage. Replace any
damaged cables.