STIEBEL ELTRON WWK 221 electronic Instruction Manual

OPERATION AND INSTALLATION
DHW heat pump
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CONTENTS | SPECIAL INFORMATION
SPECIAL INFORMATION
OPERATION
1. General information �����������������������������������������3
1.1 Safety instructions����������������������������������������������� 3
1.2 Other symbols in this documentation ����������������������� 4
1.3 Units of measurement ������������������������������������������ 4
1.4 Standardised output data �������������������������������������� 4
2. Safety����������������������������������������������������������4
2.1 Intended use������������������������������������������������������ 4
2.2 General safety instructions ������������������������������������ 4
2.3 Test symbols ������������������������������������������������������ 5
3. Appliance description ���������������������������������������5
3.1 Heat pump operating principle ������������������������������� 5
3.2 DHW heating������������������������������������������������������ 6
3.3 Appliance operation outside the application limits������� 7
3.4 Defrosting ��������������������������������������������������������� 7
3.5 Frost protection �������������������������������������������������� 7
3.6 Minimum runtime and minimum pause time�������������� 7
3.7 Connection of an external signal transmitter �������������� 7
4. Settings �������������������������������������������������������8
4.1 Display and controls��������������������������������������������� 8
4.2 Settings ������������������������������������������������������������ 9
4.3 "Quick heat-up" key �������������������������������������������� 11
4.4 Emergency shutdown������������������������������������������ 12
5. Maintenance and care ������������������������������������� 12
6. Troubleshooting �������������������������������������������� 12
INSTALLATION
7. Safety�������������������������������������������������������� 15
7.1 General safety instructions ����������������������������������� 15
7.2 Instructions, standards and regulations ������������������� 15
8. Appliance description ������������������������������������� 15
8.1 Standard delivery����������������������������������������������� 15
8.2 Required accessories ������������������������������������������ 15
8.3 Additional accessories ����������������������������������������� 15
9. Preparations ������������������������������������������������ 15
9.1 Transport ��������������������������������������������������������� 15
9.2 Storage������������������������������������������������������������ 16
9.3 Installation site and location of air extraction or air
intake�������������������������������������������������������������� 16
9.4 Siting the appliance �������������������������������������������� 17
10. Installation�������������������������������������������������� 18
10.1 Air duct (optional) ���������������������������������������������� 18
10.2 Water connection ����������������������������������������������� 20
10.3 WWK301 electronicSOL: Connection of an external
heat generator �������������������������������������������������� 20
10.4 Condensate drain ����������������������������������������������� 21
10.5 Power supply ���������������������������������������������������� 21
10.6 Assembling the appliance ������������������������������������ 24
11. Commissioning ��������������������������������������������� 24
11.1 Initial start-up��������������������������������������������������� 24
11.2 Recommissioning����������������������������������������������� 26
12. Appliance shutdown ��������������������������������������� 26
13. Troubleshooting �������������������������������������������� 26
13.1 Resetting the high limit safety cut-out ��������������������� 27
13.2 Motor overload relay������������������������������������������� 27
14. Maintenance and cleaning �������������������������������� 27
14.1 Removing the appliance cover ������������������������������� 27
14.2 Removing the casing ring������������������������������������� 28
14.3 Cleaning the evaporator��������������������������������������� 28
14.4 Drain cylinder ��������������������������������������������������� 28
14.5 Descaling the electric emergency/booster heater ������� 28
14.6 Protective anode ������������������������������������������������ 29
14.7 Valves ������������������������������������������������������������� 29
14.8 Condensate drain ����������������������������������������������� 29
14.9 Replacing the power cable ����������������������������������� 29
14.10 Fitting the casing ring ����������������������������������������� 29
14.11 Fitting the appliance cover ����������������������������������� 29
15. Specification ������������������������������������������������ 30
15.1 Dimensions and connections��������������������������������� 30
15.2 Wiring diagram ������������������������������������������������� 32
15.3 Data table �������������������������������������������������������� 34
GUARANTEE
ENVIRONMENT AND RECYCLING
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 potential risks. Children must never play with
the appliance. Children must never clean the ap-
pliance or perform user maintenance unless they
are supervised.
- Observe all applicable national and regional reg-
ulations and instructions during installation.
- The appliance is not approved for outdoor
installation.
- Observe the minimum clearances (see chap-
ter "Installation/ Preparations/ Siting the
appliance").

ENGLISH
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SPECIAL INFORMATION | OPERATION
General information
- Observe the requirements concerning the instal-
lation room (see chapter "Specification/ Data
table").
- If the appliance is permanently connected to the
power supply, ensure that the appliance can be
separated from the power supply by an isolator
that disconnects all poles with at least 3mm
contact separation. Contactors, mains isolators or
fuses can be used for this.
- Observe the safety measures to prevent contact
with dangerous 'live' currents.
- Observe the MCB/fuse protection required for
the appliance (see chapter "Specification/ Data
table").
- The power cable must only be replaced (for ex-
ample if damaged) with an original spare part by
a qualified contractor authorised by the manufac-
turer (connection typeX).
- The appliance's DHW cylinder is pressurised.
During the heat-up process, expansion water will
drip from the safety valve.
- Regularly activate the safety valve to prevent
it from becoming blocked, e.g. by limescale
deposits.
- Drain the appliance as described in chapter "In-
stallation/ Maintenance and cleaning/ Draining
the cylinder".
- Install a type-tested safety valve in the cold water
supply line.
- The maximum pressure in the cold water supply
line must be at least 20% below the response
pressure of the safety valve. If the maximum
pressure in the cold water supply line is higher,
install a pressure reducing valve.
- Size the drain so that water can drain off unim-
peded when the safety valve is fully opened.
- Fit the discharge pipe of the safety valve with
a constant downward slope and in a room free
from the risk of frost.
- The safety valve discharge aperture must remain
open to atmosphere.
OPERATION
1. General information
The chapters "Special information" and "Operation" are intended
for both users 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 Safety instructions
1.1.1 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.
1.1.2 Symbols, type of risk
Symbol Type of risk
Injury
Electrocution
Burns
(burns, scalding)
1.1.3 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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1.2 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.
These symbols show you the software menu level (in
this example level3).
1.3 Units of measurement
Note
All measurements are given in mm unless stated oth-
erwise.
1.4 Standardised output data
Explanations to determine and interpret the specified standardised
output data
Standard: EN 16147
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.
Generally, these standardised test conditions 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 conditions defined in the norm shown in
the heading of this section, any deviations can have a considerable
impact. Additional 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 conditions applicable to the relevant test match those of the
standard shown in the heading of this chapter.
2. Safety
2.1 Intended use
The purpose of this appliance is to heat domestic hot water within
the application limits stated in the chapter "Specification / data
table".
The appliance is intended for domestic use. It can be used safely
by untrained persons. The appliance can also be used in non-do-
mestic environments, e.g. in small businesses, as long as it is
used in the same way.
Any other use beyond that described shall be deemed inappro-
priate. Observation of these instructions and of the instructions
for any accessories used is also part of the correct use of this
appliance.
2.2 General safety instructions
The appliance should only be operated once it is fully installed
and all safety equipment has been fitted.
!
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 potential risks. Children must never play
with the appliance. Children must never clean the ap-
pliance or perform user maintenance unless they are
supervised.
WARNING Electrocution
Contact with live components presents a threat to life.
Damage to the insulation or to individual components
may result in a threat to life.
 If there is damage to the insulation, switch off the
power supply and arrange a repair.
All work on the electrical installation must be carried
out by a qualified contractor.
WARNING Burns
The water in the DHW cylinder can be heated to temper-
atures in excess of 60°C. There is a risk of scalding at
outlet temperatures in excess of 43 °C.
 Ensure you do not come into contact with the water
when discharged.
WARNING Burns
Touching hot components can lead to burns.
 When working on hot components, always wear
protective working clothing and safety gloves.
The pipework connected to the DHW outlet of the appli-
ance can reach temperatures in excess of 60°C.
WARNING Burns
The appliance is filled with refrigerant at the factory.
In the event of refrigerant escaping due to a leak, avoid
coming into contact with the refrigerant or inhaling the
released vapours. Ventilate the rooms affected.
WARNING Electrocution
Never operate the appliance when the casing is open,
without a cover, or without side air connectors.
!
CAUTION Injury
If objects are left on the appliance, noise emissions may
increase due to resulting vibrations, and the objects
could fall and cause injury.
 Never place any objects on top of the appliance.
!

OPERATION
Appliance description
ENGLISH
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!
Material losses
Ensure that the appliance, water pipes and safety valves
are free from the risk of frost. If you disconnect the ap-
pliance from the power supply, it is no longer protected
against frost or corrosion.
 Never interrupt the power supply to the appliance.
!
Material losses
Keep the appliance installation site free from air contam-
inated with oil or salt (chloride) and corrosive or explo-
sive substances. Avoid contaminating the installation site
with dust, hairspray or substances containing chlorine
or ammonia.
!
Material losses
Covering the air intake or air discharge leads to a reduced
air supply. If the air supply is restricted, the operational
reliability of the appliance cannot be guaranteed.
 Never cover the appliance.
!
Material losses
Only operate the appliance when the DHW cylinder has
been filled. If the DHW cylinder is empty, safety equip-
ment switches off the appliance.
!
Material losses
Heating liquids other than potable water is not permitted.
Note
The appliance's DHW cylinder is pressurised. During the
heat-up process, expansion water will drip from the safe-
ty valve.
 If water continues to drip when heating is complet-
ed, please inform your qualified contractor.
2.3 Test symbols
See type plate on the appliance.
3. Appliance description
The fully wired appliance enables DHW to be supplied efficiently
to several draw-off points using renewable energy. The appliance
extracts heat from the intake air. This heat is used to heat up the
water in the DHW cylinder with added electric power. The amount
of electric energy and time required to heat up the DHW depend
on the temperature of the air drawn in. When the air intake tem-
perature drops, the appliance output is reduced and the heat-up
time is extended.
The appliance is designed for indoor installation. The choice of
air intake and discharge on the side or top offers flexibility with
regard to possible installation sites. Accessories are required for
the vertical air intake and/or air discharge.
The appliance can be installed as a recirculation air appliance, thus
making efficient use of any available waste heat from freezers or
other heat sources, for example. Alternatively, air ducts can be
connected to use outdoor air as a heat source or to draw in air
from another room.
The ambient air can be cooled down by between 1°C and 3°C as a
result of heat extraction in the installation room or the room from
which the air is drawn. The appliance also extracts moisture from
the air, which turns into condensate. The condensate is removed
from the appliance via the condensate drain.
The appliance has an electronic control unit with LC display. You
can select the available amount of mixed water at a temperature
of 40 °C, for example. The electronic control unit makes energy
saving adjustments easier. Subject to the power supply and user
draw-off patterns, the water is heated automatically to the se-
lected set temperature.
When the air intake temperature drops, the appliance output is
reduced and the heat-up time is extended. If the value falls below
the heat pump's lower application limit, e.g. where outdoor air is
drawn in, the electric emergency/booster heater takes over DHW
heating.
External signal transmitters can be integrated via the built-in con-
tact input, e.g. a photovoltaic system to make use of solar power
generated on site.
When a hot water draw-off point is opened, the hot DHW is pushed
out of the appliance by the inflow of cold water.
The heat pump drive unit is fitted in the upper section of the ap-
pliance. The DHW cylinder is located in the lower section of the
appliance. To protect against corrosion, the DHW cylinder is coated
internally with special enamel and is additionally equipped with
an impressed current anode.
!
Material losses
If you disconnect the appliance from the power supply, it
is no longer protected against frost or corrosion.
 Never interrupt the power supply to the appliance.
!
Material losses
If outdoor air is used as a heat source when outside tem-
peratures are low, condensate may form on the appliance
if the relative humidity is unusually high, i.e. in excess
of 75% and with a room temperature of 22°C. Such
high relative humidity levels will damage the fabric of the
building and must be prevented by ventilation.
3.1 Heat pump operating principle
A closed circuit within the appliance contains refrigerant (see
"Specification/Data table"). This refrigerant evaporates at low
temperatures.
In the evaporator, which extracts heat from the air drawn in, the
refrigerant changes from a liquid into a gaseous state. A com-
pressor draws in the gaseous refrigerant and compresses it. This
increase in pressure raises the refrigerant temperature. That re-
quires electrical energy. The energy (motor heat) is not lost, but
reaches the downstream condenser together with the compressed
refrigerant. There, the refrigerant indirectly transfers heat to the
DHW cylinder. An expansion valve then reduces the still prevalent
pressure and the cycle starts again.
If a compressor is required, the appliance does not start the
compressor immediately; only once the fan's initial runtime has
elapsed. During the fan's initial runtime the appliance checks if all
the conditions required to start the compressor have been met.

OPERATION
Appliance description
6|WWK 221-301 electronic www.stiebel-eltron.com
Note
Following an interruption of the power supply, the
compressor operation remains blocked for at least one
minute. The PCB delays electronic starting by a minute,
during which the appliance goes through its initialising
process.
If the compressor subsequently fails to start, it may be
locked out by additional safety devices (motor overload
relay or high pressure switch). This block should lift after
1 to 10 minutes.
After the power supply has been re-established, the ap-
pliance continues to operate with the parameters that
were selected before the power supply was interrupted.
3.2 DHW heating
2
1
D0000050335
1 Cylinder top sensor
2 Integral sensor
The appliance is equipped with two temperature sensors.
- The cylinder top sensor captures the water temperature in
the upper section of the cylinder.
- The integral sensor is a temperature sensor affixed over the
entire cylinder height. The integral sensor determines the
average cylinder temperature.
The appliance display indicates the temperature in the upper sec-
tion of the cylinder, which is captured by the cylinder top sensor.
The appliance control unit uses the average cylinder temperature
captured by the integral sensor.
DHW heating is started when the average cylinder temperature
has fallen and the cylinder holds only 40% of the thermal energy
it held when it was heated fully to the set temperature.
The temperature captured by the sensor at the cylinder top may
still correspond to the set temperature.
For information on the heat-up time, see chapter "Specification".
The calculation of the available amount of mixed water is based
on the average cylinder temperature. The amount of mixed water
is only calculated if the water temperature in the upper section of
the cylinder is higher than 40 °C.
DHW is normally heated by the heat pump of the appliance within
the application limits (see chapter "Specification/ Data table").
Electric emergency/booster heater
Heat pump operation will be interrupted if the application lim-
its are exceeded or undershot in heat pump mode. The electric
emergency/booster heater takes over DHW heating to the selected
set temperature. Once the appliance is back within the application
limits, the electric emergency/booster heater switches off and
DHW heating continues with the heat pump.
In the event of an appliance fault, the electric emergency/booster
heater can be activated in emergency mode if the symbol “ser-
vice/fault” is flashing. See chapter "Operation/'Rapid heat-up' key/
Emergency heating mode".
In the event of a higher hot water demand on a single occasion,
use the rapid heat-up key to activate the emergency/booster heat-
er manually for one-off heat-up in addition to the heat pump. See
chapter "Operation/'Rapid heat-up' key/Rapid/comfort heating".
Set temperature adjustment subject to air temperature
If the temperature of the intake air is low, the maximum hot gas
temperature may be reached. In this case the appliance reduces
the set temperature on a temporary basis. Whilst the appliance
is operating at a reduced set temperature, the symbol for set
temperature adjustment is shown in the display.
Runtime-dependent rapid heat-up
The appliance offers runtime-dependent rapid heat-up for im-
proved comfort. When this function is enabled, and the adjusted
set temperature is not reached by the heat pump after a user-de-
fined period, the appliance switches on the electric emergency/
booster heater in parallel. As a factory default, this function is
disabled.
When the air intake temperature drops, the heat pump's heating
output is reduced and the heat-up time is extended. In the case
of installation with outdoor air intake, we recommend enabling
"runtime-dependent rapid heat-up" during the winter months and
as required in spring/autumn when outside temperatures are low.
Note that DHW heating with the electric emergency/booster heater
uses more power than just using the heat pump.
To prevent excessive power consumption, disable the function in
summer and in spring/autumn if at all possible. When the function
is activated, we recommend only reducing the factory preset of 8
hours if absolutely necessary for the same reason.
WWK301electronicSOL: Connection of an external heat
generator
!
Material losses
Even if an external heat generator is connected, do not
disconnect the appliance from the power supply as oth-
erwise it is not protected against frost and corrosion. The
power supply must not be interrupted even in winter,
when it is possible that DHW heating is only being pro-
vided via the external heat generator.
The appliance is equipped with an integral smooth tube heat ex-
changer to which an external heat generator can be connected
(e.g. a solar thermal system or central heating system). The DHW
cylinder has sensor wells available for this in various positions.
Once during commissioning, the qualified contractor must match
the controls between the appliance and the external heat gen-
erator.

OPERATION
Appliance description
ENGLISH
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3.3 Appliance operation outside the application
limits
 To guarantee fault-free operation of the appliance, make sure
you operate the appliance within its application limits (see
chapter "Specification/ Data table").
3.3.1 Application limits for heat pump operation
Air intake temperature lower than the application limit
If the air intake temperature falls below the lower application
limit, the appliance blocks the compressor. The compressor sym-
bol flashes. This means the compressor receives a DHW demand,
but the compressor is blocked by the control unit. Heating oper-
ation is now only possible with the electric /emergency booster
heater.
After one hour, the appliance starts the fan for two minutes and
checks whether the conditions for restarting the compressor have
been fulfilled. If the air temperature is higher by the hysteresis
value than the lower application limit, the compressor is released
for operation.
The electric emergency/booster heater remains operational until
the set DHW temperature is reached or until the lower application
limit is exceeded by the hysteresis value (approx. 1 K).
Air intake temperature higher than the application limit
If the air intake temperature exceeds the higher application limit,
the appliance blocks the compressor. Heating operation is now
only possible with the electric /emergency booster heater. After
one hour, the appliance starts the fan for two minutes and checks
whether the conditions for restarting the compressor have been
fulfilled. If the air temperature is lower by the hysteresis value
than the higher application limit, the compressor is released for
operation.
The electric emergency/booster heater remains operational until
the set DHW temperature is reached or until the temperature falls
below the higher application limit by the hysteresis value (ap-
prox.1 K).
3.4 Defrosting
Low air intake temperatures may result in the formation of hoar
frost on the evaporator, subject to relative humidity and DHW
temperature. The appliance is equipped with an electronic de-
frost monitor. DHW heating is interrupted during the defrosting
process. The appliance switches off the fan during the defrosting
process. The compressor continues to run. The defrosting process
is shown on the appliance display.
A maximum defrost time is stored in the appliance. If the maxi-
mum defrost time is exceeded, the appliance stops the defrosting
process and releases the electric emergency/booster heater.
Note
Heat-up times are longer while the evaporator is defrost-
ing.
Note
The appliance starts the defrosting process as soon as
the compressor runtime reaches the "Defrost required"
time span stored in the appliance.
3.5 Frost protection
The appliance activates the frost protection function if the integral
sensor in the DHW cylinder captures a temperature below 10°C.
The appliance then heats the water by means of the heat pump
and the electric emergency/booster heater. The heat pump and
electric emergency/booster heater switch off when the tempera-
ture captured by the integral sensor reaches 18°C.
3.6 Minimum runtime and minimum pause time
!
Material losses
When operating with external switching devices that can
interrupt the power supply to the appliance, such as time
switches, energy management systems or home automa-
tion systems, observe the following conditions:
- The minimum ON time is 60 minutes.
- The minimum pause time following a shutdown is
20 minutes.
- The appliance should not be switched on/off more
than 10 times per day.
- The breaking capacity of the switching actuator
must meet the protection requirements (see chapter
"Specification / Data table").
3.7 Connection of an external signal transmitter
Note
This type of connection must only be carried out by a
qualified electrician.
External signal transmitters can be integrated via the built-in con-
tact input, e.g. a PV system to make use of solar power generated
on site.
The appliance has a second set temperature preselected at the
factory. This is activated in the event of an external switching
signal. Set temperature2 is higher ranking than the standard set
temperature while there is an external switching signal. Following
a one-off activation (signal is present for at least 1 minute), set
temperature2 applies for at least 20minutes and is ranked higher
than set temperature1.
You can change set temperature 2 on the appliance (see chapter
"Settings/Settings/Set temperature 2").

OPERATION
Settings
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4. Settings
4.1 Display and controls
Note
15seconds after every operation, the appliance auto-
matically reverts to the default display (amount of mixed
water) and saves the set value.
electronic comfort
2
5
4
D0000059162
3
1
1 "Mixed water volume" display (l|40°C)/
"Actual temperature upper cylinder section" display/
"Set temperature1" display/
“Set temperature2” display/
"Fault code" display
2 "Plus" key
3 "Minus" key
4 "Quick heat-up" key
5 "Menu" key
4.1.1 Symbols
Symbol Description
Mixed water volume: The currently available amount of mixed
water at 40°C and at 15°C cold water temperature is shown.
Set temperature adjustment: Subject to intake temperature and
hot gas temperature, the appliance may temporarily reduce the set
temperature to the actual value captured by the integral sensor.
The appliance displays the "set temperature adjustment" symbol
and blocks DHW heating until the actual temperature captured by
the integral sensor is 6K below the temporary set temperature.
DHW heating is then re-enabled and the originally selected set
temperature is again applied.
Actual temperature: The current actual temperature is shown. The
actual temperature indicates the temperature in the upper section
of the DHW cylinder and therefore largely corresponds to the outlet
temperature.
Set temperature
External signal transmitter: Set temperature2 is the DHW tempera-
ture to which the appliance regulates if an external signal transmit-
ter is connected and active.
Standby: The symbol flashes, if the appliance PCB and load (com-
pressor) are separately supplied with voltage. This connection
option is required, if the appliance is to be operated via switchable
sockets in an energy management system (see "Electrical connec-
tion" chapter) for example.
electric emergency/booster heater: This symbol indicates the pres-
ence of a demand on this component. This symbol being displayed
does not necessarily mean that the electric emergency/booster
heater is in operation.
Heat pump: This symbol indicates the presence of a demand on
this component. This symbol being displayed does not necessarily
mean that the compressor is running.
Defrost active
Service/fault: If the "service/fault" symbol appears on the display,
inform your qualified contractor. Continuous illumination of the
symbol indicates that the fault is not preventing appliance op-
eration. A flashing "Service/fault" symbol indicates that water is
not being heated and that it is essential you notify your qualified
contractor. Switching the appliance to emergency mode is a special
case. The electric emergency/booster heater will then heat the
water despite the flashing "Service/fault" symbol.
The symbols for electric emergency/booster heater and heat pump
are displayed when there is a demand for these appliance compo-
nents. These symbols being displayed does not necessarily mean
that the electric emergency/booster heater and the heat pump
are running.
Example: The appliance is in rapid/comfort heat-up mode. The
electric emergency/booster heater switches off when the temper-
ature in the upper cylinder section has reached 65°C. The heat
pump has not yet heated the lower section to 65°C and the rapid/
comfort heat-up function has therefore not been terminated yet.
The "electric emergency/booster heater" symbol is displayed until
the rapid/comfort heating has terminated.

OPERATION
Settings
ENGLISH
www.stiebel-eltron.com WWK 221-301 electronic | 9
4.2 Settings
Menu
In default display mode, the display shows the amount of mixed
water.
The "Menu" key allows you to call up all
information and adjustment options in
sequence. The relevant symbol appears.
 Menu
 "Mixed water volume" display
 "Actual temperature" display
 Set temperature 1
 Set temperature 2
 Fan speed
 "Air intake temperature" display
 Enabilng the "runtime-dependent rapid heat-up" function
 Time input for the "runtime-dependent rapid heat-up" function
 Changing units
 Fault code
 E fault code
 "Mixed water volume" display
The currently available amount of mixed
water at 40°C and at 15°C cold water
temperature is shown.
"--L" is shown if less than 10l mixed
water is available.
DHW demand for Mixed water volume at 40°C
Bath 120-150 l
Shower 30-50 l
Washing hands 2-5 l
The amount of mixed water that can be achieved depends on the
cylinder capacity and the set temperature selected.
 "Actual temperature" display
In the "Mixed water volume" menu, press
"Menu" once to access the "Actual tem-
perature" menu.
The "Actual temperature" symbol ap-
pears.
The current actual temperature is shown.
The actual temperature indicates the
temperature in the upper section of the
DHW cylinder and largely corresponds to
the outlet temperature.
 Set temperature 1
Note
For hygiene reasons, never set the DHW temperature
below 50°C.
Set temperature1 is the DHW temperature to which the appliance
regulates if no external signal transmitter is connected and active.
Set temperature1 is factory-set to 55°C.
In the "Actual temperature" menu, press
"Menu" once to access the "Set temper-
ature 1" menu.
The "set temperature1" symbol appears.
Adjust set temperature1 from 20°C to
65°C using the “Plus” and “Minus” keys.
Note
Another way to adjust set temperature1 is to press the
"Plus" or "Minus" keys from within the default display
(mixed water volume).
Frost protection
Only frost protection remains active if
you set the set temperature to below
20°C using the "Minus" key. The display
shows "--°C".
 Set temperature 2
Note
For hygiene reasons, never set the DHW temperature
below 50°C.
Set temperature2 is the DHW temperature to which the appliance
regulates if an external signal transmitter is connected and active.
In the "Set temperature1" menu, press
"Menu" once to access the "Set temper-
ature2" menu.
The "External signal transmitter" symbol
appears.
Adjust set temperature2 from 20°C to
65°C using "Plus" and "Minus".

OPERATION
Settings
10|WWK 221-301 electronic www.stiebel-eltron.com
Operation with external signal transmitter
!
Material losses
See "Permissible voltage range for external signal trans-
mitters" in the "Specification/data table" chapter.
As standard, the appliances feature the ability to assign a spe-
cific, individual set DHW temperature ("set temperature2") to a
connected external signal transmitter, such as a PV system or a
low tariff transmitter.
This set temperature 2 is activated if the terminal connected to
the external signal transmitter receives a signal (see "Electrical
connection/external signal transmitter connection option" chap-
ter). While activated, set temperature2 replaces the standard set
DHW temperature (set temperature1).
If set temperature2 is activated by the external signal transmitter,
this set temperature will then be active for at least 20minutes.
If the external signal remains active after these 20minutes have
passed, the compressor will run until the external signal drops
out. If not, the selected set temperature1 is re-enabled.
When the relevant DHW set temperature has been reached, the
compressor switches off and remains off for a minimum idle time
of 20minutes.
The following diagram illustrates the connections by means of a
sample signal sequence from an external signal transmitter.
Example:
- Water temperature = 55°C
- Set temperature 1 = 50°C
- Set temperature 2 = 65°C
A
1
0
0510 15 20 25 30 35 40 45 50 55 60 65 70 75 t [min]
B
1
1
0 2
0510 15 20 25 30 35 40 45 50 55 60 65 70 75 t [min]
D0000034613
A External signal
B Compressor
1 20 min. minimum runtime, set temperature2
2 20 min. minimum compressor idle time
Note
An external signal must be present for at least 60sec-
onds before the control unit responds to it. This will for
example prevent a brief burst of sunshine from triggering
a heat-up process, which due to a lack of further insola-
tion can then not be supplied with PV power generated
on site.
 Fan speed
The current set fan output appears, iden-
tified by a preceding F.
Note
Do not change the fan output. Your qualified contractor
has set this value during commissioning.
 Air intake temperature display
An "A" appears as the intake temperature
symbol.
The current air intake temperature is
displayed.
The air intake temperature is only dis-
played while the appliance fan is run-
ning. If it is not possible to establish an
air intake temperature, two dashes are
shown.
 Enabilng the "runtime-dependent rapid heat-up" function
Note
Only use runtime-dependent rapid heat-up when re-
quired, and only at low intake temperatures, e.g. with
outdoor air operation in winter and in spring/autumn if
appropriate. Avoid using runtime-dependent rapid heat-
up at intake temperatures for which heating without the
electric emergency/booster heater normally covers the
prevailing demand. In such cases, selecting too short a
runtime leads to unnecessary electricity bills. The facto-
ry-preset runtime is 8hours and should not be less than
this with the function activated continuously.
To prevent excessive power consumption, disable the
function in summer and in spring/autumn if at all pos-
sible.
For improved comfort, the appliance offers runtime-dependent
rapid heat-up. If the selected set temperature is not reached by the
heat pump after a user-defined period, the appliance switches on
the electric emergency/booster heater in parallel to back up the
heat pump (subject to this function being enabled). Once the set
value has been reached, the electric emergency/booster heater
remains inactive until the set time has elapsed again following a
heat demand. As a factory default, this function is disabled.
In the case of installation with outdoor air intake, we recommend
enabling "runtime-dependent rapid heat-up" during the winter
months and as required in spring/autumn when outside temper-
atures are low. This prevents any loss of comfort if, say, the heat
pump output falls as a result of the outside temperature dropping
when taking in outdoor air, and the heat-up time is thus extended.
The period after which the electric emergency/booster heater
provides automatic back-up needs to be selected individually by
the user based on local conditions. DHW consumption and the
expected intake temperatures need to be considered.
This function is set in two stages. First enable the function and set
the runtime in the second parameter.

OPERATION
Settings
ENGLISH
www.stiebel-eltron.com WWK 221-301 electronic|11
The tHE0 setting disables the "runt-
ime-dependent rapid heat-up" function.
This function is enabled via setting tHE1.
The function is disabled at the factory.
Switch between the tHE0 and tHE1 set-
tings using the "Plus" and "Minus" keys.
The tHE1 setting allows the electric
emergency/booster heater to cut in if
the set temperature is not reached after
expiry of the runtime selected below.
 Time input for the "runtime-dependent rapid heat-up"
function
Set the runtime using the "Plus" and
"Minus" keys. After the set number of
hours, the appliance checks whether the
set temperature has been reached. If this
is not the case, the appliance switches on
the electric emergency/booster heater.
The factory default is 8hours.
thE1
tE08
thE0
t
D0000052266
1
2
1 Heat pump symbol
2 Electric emergency/booster heater symbol
tHE0 Runtime-dependent rapid heat-up disabled
tHE1 Runtime-dependent rapid heat-up enabled
tE08 Adjustable number of hours (e.g. 8 in this case) during
which heating is only provided by the heat pump
 Changing units
You can select whether the temperatures and the volume details
are displayed in SI units or US units. If you select 1, the values are
displayed in degrees Celsius and litres. If you select 0, the values
are displayed in degrees Fahrenheit and gallons.
Press the "Menu" key until "SI" appears
in the display.
Using the "Plus" and "Minus" keys, set
whether the display should use SI units
(1) or US units (0).
 Fault code
If the "Service/fault" symbol illuminates
or flashes, you can query the fault code
using the "Menu" key. This menu remains
disabled if no fault has arisen.
See chapter "Troubleshooting/ Fault codes".
 E fault code
A fault code preceded by E appears if the fault relates to the re-
frigerant circuit. Notify a qualified contractor.
4.3 "Quick heat-up" key
Press the "Quick heat-up" key.
The "heat pump" and "electric emergen-
cy/booster heater" symbols appear.
4.3.1 Quick/comfort heat-up
Normally, the "Rapid heat-up" key is used to enable rapid/comfort
heating, which enables you to cover unexpectedly high DHW de-
mands without changing any of the appliance's standard settings.
If quick/comfort heat-up is activated manually by pressing the
relevant key, the heat pump and the electric emergency/boost-
er heater will start in parallel, irrespective of the selected set
temperature, and will remain active until the DHW temperature
in the cylinder has reached 65°C. To save energy, the electric
emergency/booster heater switches off early, as soon as a tem-
perature of 65°C has been achieved in the upper cylinder section
(quick heat-up). The rapid/comfort heating function remains active
until a temperature of 65°C has been achieved throughout the
DHW cylinder (comfort heating). The appliance then automatically
switches back to the previously set parameters.
Note
The "electric emergency/booster heater" and "heat pump"
symbols are displayed until the rapid/comfort heating
terminates.
During rapid/comfort heating, the "electric emergency/
booster heater" symbol is displayed until the heat pump
has heated the entire cylinder content to 65°C and the
function terminates. The electric emergency/booster
heater already switches off when the 65°C has been
achieved in the upper cylinder section.
Note
If the quick/comfort heat-up has been activated unin-
tentionally, you can cancel the function by lowering the
set temperature.
 Hold down the "Minus" key, until you hear a clicking
noise caused by the heat pump and emergency/
booster heater switching off. At the same time, the
set temperature also reverts to the value that was
selected before quick/comfort heat-up was enabled.

OPERATION
Maintenance and care
12|WWK 221-301 electronic www.stiebel-eltron.com
4.3.2 Emergency mode
If the appliance is faulty, you can use the emergency mode to
activate the electric emergency/booster heater.
The compressor shuts down if, following a DHW demand, no tem-
perature increase is captured for 13 hours (52 intervals of 15min-
utes each, during which the temperature increase is <0.25°C re-
spectively). The "service/fault" symbol flashes on the display and
a fault code indicates that the appliance is not heating.
In this case you can activate emergency mode by pressing the
"Quick heat-up" key. After the "Quick heat-up" key has been
pressed, the indicated fault code increments by a value of 256,
as the fault codes are added together (see fault code table in
the "Troubleshooting" chapter). "Service/fault" symbol continues
flashing. The electric emergency/booster heater is activated.
The current set temperature (set temperature1 or set tempera-
ture2) is ignored. In emergency mode, the appliance operates
with a fixed set temperature of 40°C. Following one-time enabling
of this function by means of the "Quick heat-up" key, this function
remains enabled for 7days.
Following 7days of emergency operation the electric emergency/
booster heater is disabled. The fault code shown on the display
decrements by256.
If you press "Rapid heat-up" again within the 7days of emergency
heating mode, the 7-day runtime for emergency heating mode
will restart.
If the 7-day runtime for emergency heating mode has expired,
you can restart emergency heating mode for a further 7days by
pressing "Rapid heat-up".
Pressing the "Quick heat-up" key only enables emergency mode if
an error with fault code8 occurred previously. In standard mode
pressing the "Quick heat-up" key only triggers one-time heat-up
of the DHW cylinder.
Emergency mode is disabled by an interruption of the power sup-
ply. The appliance tries again to heat with the heat pump. Fault
code8 is only set after 13hours. Only then can emergency mode
be manually re-enabled via the "Quick heat-up" key.
4.4 Emergency shutdown
In the event of an emergency, carry out the following steps:
 Interrupt the power supply by unplugging the appliance from
the mains or by tripping the MCB.
 Shut off the cold water supply.
 Immediately notify a qualified contractor, as the appliance
is not protected against corrosion while the power supply is
interrupted.
5. Maintenance and care
WARNING Electrocution
-Only clean the exterior of the appliance.
-Never open the appliance.
-Do not insert objects through the grille into the in-
terior of the appliance.
-Never spray the appliance with water.
-Never spray water into the appliance.
!
WARNING Injury
Maintenance work, such as checking electrical safety,
must only be carried out by a qualified contractor.
Appliance
components
Care and maintenance tips
Casing Use a damp cloth to clean the casing sections. Never use
abrasive or corrosive cleaning agents.
Air intake
grille/ air dis-
charge grille
Clean the air intake grille and air discharge grille every six
months. Cobwebs or other kinds of contamination can re-
strict the air supply to the appliance.
DHW cylinder The DHW cylinder is equipped with a maintenance-free im-
pressed current anode to safeguard it against corrosion. The
power supply must not be interrupted while the appliance is
filled with water to enable the impressed current anode to
provide protection. Otherwise there is a risk of corrosion.
Electric emer-
gency/booster
heater
Have the electric emergency/booster heater descaled from
time to time. This will extend the service life of the electric
emergency/booster heater.
Appliance Have the safety assembly and the evaporator checked regu-
larly by a qualified contractor.
Condensate
drain
Undo the condensate drain. Check that the condensate drain
is clear and remove any dirt from the condensate drain
connection.
Scaling
Almost every type of water will deposit limescale at high tem-
peratures. This settles inside the appliance and affects both the
performance and service life. A qualified contractor who knows
the local water quality will tell you when the next service is due.
 Check the taps regularly. Limescale deposits at the tap out-
lets can be removed using commercially available descaling
agents.
 Regularly activate the safety valve to prevent it from becom-
ing blocked, e.g. by limescale deposits.
6. Troubleshooting
Problem Cause Remedy
The compressor
is operational,
but the fan is
off.
If the appliance is in defrost
mode, it may take up to an
hour for the fan to switch on
again. The defrosting process
is shown on the display.
No action required. If this
problem continues for more
than one hour, please consult
a qualified contractor.
No hot water is
available.
No power at the appliance. Check that the appliance
is connected to the power
supply.
A fuse/MCB in the fuse box has
blown/tripped.
Check whether the fuses/
MCBs in your fuse box have
blown/tripped. If required,
disconnect the appliance from
the power supply and replace
the fuses/reset the MCBs.
Contact your qualified con-
tractor if the fuse/MCB blows/
trips again after the appliance
is re-connected to the power
supply.
The air intake or air discharge
of the appliance is blocked.
Check the air intake grille and
air discharge grille for dirt
accumulations. Remove any
dirt (see the "Maintenance
and care" chapter). Do not
hang towels over the air in-
take or discharge.

OPERATION
Troubleshooting
ENGLISH
www.stiebel-eltron.com WWK 221-301 electronic|13
Problem Cause Remedy
The appliance reduces the
set value temporarily to the
current actual value on the in-
tegral sensor subject to the in-
take temperature and the hot
gas temperature, as required.
No action required. The ap-
pliance displays the "Set tem-
perature adjustment" symbol
and blocks DHW heating until
the actual temperature cap-
tured by the integral sensor is
6K below the temporary set
temperature. DHW heating is
then re-enabled and the orig-
inally selected set tempera-
ture is again applied.
The air intake temperature
exceeds the upper application
limit (see "Specification/ Data
table" chapter). The appli-
ance safety equipment has
responded and the appliance
has switched off automatically.
Wait for the appliance to cool
down. Call a qualified con-
tractor if the appliance does
not restart automatically.
The air intake temperature
falls below the lower applica-
tion limit (see "Specification/
Data table" chapter). The
evaporator is being defrosted
intermittently.
Wait until the appliance re-
starts automatically.
The appliance output data are
calculated according to stand-
ard, using the intake temper-
ature specified in the data
table. Below this temperature
the appliance efficiency and
output decrease. The heat-up
time is extended.
Use runtime-dependent rapid
heat-up if necessary.
If the water does not heat up
or the heat pump runtime is
very long, this may be due to
an excessively low intake tem-
perature.
No action required. Use runt-
ime-dependent rapid heat-up
if necessary.
The appliance
is not heating
the DHW cylin-
der, although
the "heat
pump" symbol
is illuminated.
The compressor lockout time
has not yet elapsed. Once the
compressor has been switched
off, it will only be switched
back on again after the
20minute compressor lockout
time has elapsed.
No action required.
The safety valve
of the cold
water supply
line is dripping.
The appliance is under mains
water pressure. During the
heat-up process, expansion
water will drip from the safety
valve.
Notify a qualified contractor if
water continues to drip when
heat-up has been completed.
The condensate
drain drips.
The surface temperature of
the evaporator is lower than
the dew point temperature of
the ambient air. Condensate
forms.
The amount of condensate
depends on the humidity
level of the ambient air.
The room tem-
perature drops
too low.
Operation of the appliance
can cause the room temper-
ature to fall by 1 to 3°C. If
the room temperature falls
by more than 5°C, check the
room size (see the "Specifi-
cation/Data table" chapter).
Increasing the room size by
opening a door to another
room will remedy this.
High power
consumption
The lower the intake tempera-
ture, the lower the heat pump
efficiency.
Avoid low intake tempera-
tures if at all possible.
Runtime-dependent rapid
heat-up is activated.
Only activate this function if
really necessary or increase
the runtime during which the
heat pump operates alone
and the electric emergency/
booster heater is blocked via
your selected parameters.
Problem Cause Remedy
Service/fault
symbol is per-
manently on.
See the “Fault codes” chapter. Notify a qualified contractor.
Service/fault
symbol flashes
and the water
does not heat
up.
See the “Fault codes” chapter. It is imperative that you notify
a qualified contractor quickly.
A flashing "service/fault"
symbol indicates that a fault
has occurred and the heat
pump is no longer heating.
Defrost symbol
is shown.
The appliance is in defrost
mode.
No action required.
The heat pump
symbol is flash-
ing.
The lower application limit
of the heat pump has been
undershot.
No action required. The
electric emergency/booster
heater takes over the DHW
heating.
There is a heat demand, but
the compressor is locked out.
No action required. The com-
pressor restarts automatically
after the compressor lockout
time has elapsed. The com-
pressor lockout time lasts
20minutes once the com-
pressor has been shut down.
The symbol stops flashing
automatically.
The electric
emergency/
booster heater
symbol is flash-
ing.
A temperature controller has
switched off the electric emer-
gency/booster heater during
rapid heat-up.
No action required. The ap-
pliance continues the quick
heat-up process using the
heat pump. The symbol stops
flashing when the controller
re-enables the electric emer-
gency/booster heater. The
symbol extinguishes when
the temperature throughout
the DHW cylinder reaches the
set temperature of 65°C.
The "electric
emergency/
booster heater"
symbol illu-
minates even
though the ap-
pliance is with-
in the applica-
tion limits and
"rapid heat-up"
has not been
pressed.
The “runtime-dependent rapid
heat-up” function is enabled
and currently in use.
No action required.
The electric
emergency/
booster heater
symbol is illu-
minated but the
electric emer-
gency/booster
heater is not
operational.
The electric emergency/
booster heater lights up when
there is a demand. The inter-
nal controller of the electric
emergency/booster heater
may have ended electric
heating. A possible cause
may be a fault in the electric
emergency/booster heater. A
possible cause may be that the
high limit safety cut-out has
responded.
Have a qualified contractor
check whether the controller
of the electric emergency/
booster heater is set correct-
ly. The controller must be
turned fully clockwise. Have a
qualified contractor check the
high limit safety cut-out.

OPERATION
Troubleshooting
14|WWK 221-301 electronic www.stiebel-eltron.com
Fault code
You can call up a fault code if the Service/fault symbol is flashing
or continuously lit on the display.
Keep pressing "Menu" until the fault code
appears.
Fault
code
Service/
fault
symbol
Fault description Remedy
2 permanent-
ly on
The sensor at the cylinder top is
faulty. The actual temperature
display changes over to the
integral sensor. The appliance
continues to deliver heat. The
amount of mixed water shown
is always less than 10 litres.
4 permanent-
ly on
The integral sensor is faulty.
In the event of a faulty integral
sensor, the integral sensor is
set to the value at the cylinder
top sensor and amount of
mixed water is calculated using
this value. The appliance con-
tinues to deliver heat.
Notify a qualified con-
tractor.
6 flashes The sensor at the cylinder top
and the integral sensor are
faulty. The appliance no longer
delivers heat.
Notify a qualified con-
tractor.
8 flashes The appliance has ascertained
that the DHW cylinder has not
been heated for 13hours, de-
spite there being a demand.
You can continue to
use the appliance by
activating emergency
mode. See chapter
"Emergency mode".
16 permanent-
ly on
Short circuit impressed current
anodeor protective anode
faulty
Immediately notify a
qualified contractor,
as the appliance is not
protected against cor-
rosion if the impressed
current anode is faulty.
32 flashes
The appliance is operating with
an empty cylinder or the appli-
ance is not delivering heat.
Fill the appliance. The
fault code disappears
and the appliance
starts.
The anode current is inter-
rupted. The appliance does not
heat up.
The qualified contrac-
tor needs to check the
impressed current
anode and the wiring.
64 flashes After an hour of defrosting, the
evaporator temperature has not
yet reached 3 °C. The compres-
sor is faulty.
The fault is reset once
the evaporator temper-
ature rises to 3 °C. If
the fault is continuous-
ly displayed, a solenoid
diverter valve fault may
be the cause. Notify a
qualified contractor.
128 permanent-
ly on
No communication between
controller and programming
unit. The most recently selected
set values are active.
256 flashes Manually activated emergency
mode (only electric emergency/
booster heater enabled)
See chapter "Appliance
description/ Emergen-
cy mode".
If several faults occur, the fault codes are added up.
Example: If both the sensor at the cylinder top and the integral
sensor are faulty, the display shows fault code6(= 2+4).
Application scenarios for emergency mode
If the appliance shows fault code8, you can manually activate
emergency mode. If a different fault occurred previously, but did
not cause the appliance to switch off, the display will show a fault
code that is the result of several faults added together.
Listed below are the fault codes which will allow you to enable
emergency mode.
Fault code displayed
8 8
10 Fault code 8 + fault code 2
12 8+4
24 8+16
26 8+2+16
28 8+4+16
138 8+2+128
140 8+4+128
152 8+16+128
154 8+2+16+128
156 8+4+16+128
When the appliance is operating in emergency mode, the fault
code shown is incremented by 256.
E fault code
Press "Menu" repeatedly. If a fault code preceded by E is dis-
played, please notify a qualified contractor. The fault code gives
the qualified contractor information about the cause of the fault
(see "Troubleshooting" chapter).
Notifying a qualified contractor
If you cannot remedy the fault, notify your qualified contractor.
To facilitate and speed up your request, provide the number from
the type plate (000000-0000-000000). The type plate can be found
on the left, above the DHW outlet connection.
Sample type plate
000000-0000-000000
D0000040661
1
1 Number on the type plate

ENGLISH
www.stiebel-eltron.com WWK 221-301 electronic|15
INSTALLATION
Safety
INSTALLATION
7. Safety
Only a qualified contractor should carry out installation, commis-
sioning, maintenance and repair of the appliance.
7.1 General safety instructions
We guarantee trouble-free function and operational reliability only
if original accessories and spare parts intended for the appliance
are used.
7.2 Instructions, standards and regulations
Note
Observe all applicable national and regional regulations
and instructions.
Take note of the appliance type plate and chapter "Specification".
8. Appliance description
The thermal output of the heat pump depends on the temperature
of the intake air and the selected set DHW temperature.
The DHW sizing of the appliance should consider the appliance
output dependent on the temperature of the intake air and the
resulting heat-up time.
If the heating output is low and the "runtime-dependent rapid
heat-up" function is enabled, DHW heating is backed up by the
electric emergency/booster heater. Note that DHW heating with
the electric emergency/booster heater uses more power than just
using the heat pump. To prevent excessive power consumption,
disable the function in summer and in spring/autumn if at all
possible. The function is deactivated in the delivered condition.
8.1 Standard delivery
Note
Accessories are located in the corners of the packaging.
Remove the accessories before disposing of the pack-
aging.
D0000046701
1
1 Corners of the packaging
The following are delivered with the appliance:
- Condensate drain bend
- For the "Cold water inlet" and "DHW outlet" connections: 2
insulated screw fittings comprising a flanged pipe, a gasket,
a union nut and an insulating sleeve
- 2 reducers (DN 200 to DN 160) for the side air intake and dis-
charge connections
8.2 Required accessories
Various safety assemblies are available that are selected according
to supply pressure. These type-tested safety assemblies protect
the appliance against unacceptable excess pressure.
8.3 Additional accessories
- Condensate pump (if the condensate cannot be drained off
with a naturally occurring fall)
- Accessories set for diverting the air flow routed horizontally
on site in a vertical direction (DN 160). This enables a vertical
air routing for the air intake and/or air discharge.
- Air duct accessories such as insulated flexible tubing, folded
spiral-seam tube and profiles, wall ducts with weather grille
9. Preparations
9.1 Transport
!
CAUTION Injury
 Observe the weight of the appliance.
 Use suitable transport aids (e.g. a sack truck) and
enough personnel for transportation.
!
Material losses
The appliance has a high centre of gravity and low over-
turning moment.
 Safeguard the appliance against falling over.
 Only set the appliance down on an even base.
!
Material losses
The appliance casing is not designed to withstand strong
forces. Incorrect handling can lead to material losses of
considerable extent.
 Observe the information on the packaging.
Only remove the packaging shortly before the installation.
Where possible, do not unpack the appliance until it has arrived
in the installation room. For transport and handling leave the ap-
pliance in its packaging and on the pallet. This enables brief hori-
zontal transport and provides places to hold onto during transport.
If the appliance has to be unpacked before transportation, we
recommend using a sack truck. Pad the contact surfaces to avoid
damaging the appliance.
Secure the appliance to the sack truck using a strap. Pad between
the strap and the appliance and avoid overtightening the strap.
Where stair wells are narrow, you can carry the appliance by the
handles on the sack truck and the foot of the appliance.

16|WWK 221-301 electronic www.stiebel-eltron.com
INSTALLATION
Preparations
Vehicular transport
!
Material losses
The appliance must generally be stored and transported
vertically.
The appliance may be transported horizontally for brief periods,
over a maximum distance of 160km and on made-up roads.
Strong shocks are not permissible.
!
Material losses
If transported horizontally, the appliance must always be
laid on the shaded side of the box.
The appliance must not remain in a horizontal position
for more than 24hours.
If the appliance was transported horizontally, leave it to
rest in a vertical position for at least one hour before
commissioning.
 Observe the information on the packaging.
D0000034797
1
1 Recessed grips
Transport from vehicle to installation room
The cardboard box has reinforced recessed grips along the top.
You can use these recessed grips, as well as the pallet at the lower
end, to carry the appliance into the installation room. Take note
of the weight of the appliance and ensure a sufficient number of
personnel is available for handling the appliance.
9.2 Storage
If it is necessary to store the appliance for a prolonged period
before installation, observe the following information:
- Only store the appliance in a vertical position. Never store
the appliance horizontally.
- Store the appliance in a location that is dry and largely
dust-free.
- Protect the appliance from coming into contact with corrosive
substances.
- Ensure the appliance is not subjected to shocks or vibrations.
9.3 Installation site and location of air extraction
or air intake
!
Material losses
Observe the lower application limit for the appliance. The
temperature of the air discharged from the appliance may
be lower than this value. This may arise if DHW is drawn
off intensively, for example, i.e. in excess of usual house-
hold consumption. If cold air is admitted into rooms in
the building, this can lead to frost damage, e.g. on water
pipes.
!
Material losses
Please observe the installation site requirements listed
below and the air extraction or intake locations. Failure
to observe this point puts the appliance at risk of damage.
- The appliance is not approved for outdoor installation.
- If outdoor air is used as a heat source when outside temper-
atures are low, condensate may form on the appliance if the
relative humidity is unusually high, i.e. in excess of 75% and
with a room temperature of 22°C. Such high relative humid-
ity levels will damage the fabric of the building and must be
prevented by ventilation.
- The installation site must be free from flammable, highly
combustible gases and substances, as well as high levels of
dust.
- The installation room must be free from the risk of frost.
Please note that the temperature in the installation room, or
in the room into which the air is admitted, can fall below 0°C
during the appliance runtime.
- The ambient temperature of the appliances and the air intake
temperature must be within the permissible application lim-
its (see "Specification/ Data table" chapter).
- The floor of the installation room must be level and have suf-
ficient load bearing capacity. Take note of the weight of the
appliance with a full DHW cylinder (see "Specification/ Data
table"). A floor with insufficient load bearing capacity is in
danger of collapse. If the appliance is not level, there may be
a risk of appliance damage.
- The size of the installation room must correspond to the
appliance application limits (see "Specification/ Data table"
chapter).
- Observe the safety clearances and protection zones.
- Always leave sufficient space to provide access for installa-
tion, maintenance and cleaning. Observe the minimum clear-
ances (see "Preparations/ Siting the appliance").
- Ensure the operation of other equipment in the installation
room is not impaired.
- To keep the duct lengths as short as possible, we recommend
installing the appliance close to the kitchen or bathroom.
- To prevent adverse effects from operating noise, never install
the appliance close to bedrooms.

ENGLISH
www.stiebel-eltron.com WWK 221-301 electronic | 17
INSTALLATION
Preparations
Examples of unacceptable
installations
atmospheres containing ammonia sewage works, pigsties
substances which block the evap-
orator
air containing oil or fat, dust (cement,
flour, etc.). Note: If the air contains hair-
spray (e.g. in hairdressing salons), the
appliance should be operated at shorter
maintenance intervals.
saline environments Coastal installations (< 200m from the
coast) can reduce component service life.
atmospheres containing chlorine
or chloride
swimming pools, salt works
atmospheres containing thermal
water
Areas in proximity to high frequen-
cy machines
inverters for large motors, radar, etc.
Note
The appliance output data are calculated according to
standard, using the intake temperature specified in the
data table. Below this temperature the appliance efficien-
cy and output decrease. The heat-up time is extended.
Sound emissions
The sound emissions are louder on the air intake and air discharge
sides of the appliance than on the closed sides.
 Never direct the air intake or air discharge towards
noise-sensitive rooms of the house, e.g. bedrooms.
Note
For details on sounds emissions, see chapter "Specifica-
tion/ Data table".
Note
The fan speed affects noise emissions.
Never set the fan speed higher than necessary.
See chapter "Commissioning/ Fan setting subject to pres-
sure drop".
9.4 Siting the appliance
Note
Accessories are located in the corners of the packaging.
Remove the accessories before disposing of the pack-
aging.
 Carefully undo the cardboard packaging at the clips.
D0000034797
1
1 Cardboard packaging clips
The appliance is secured to the pallet with metal brackets and
screws. The metal brackets are hooked on to the feet underneath
the floor plate of the appliance.
1. 2.
D0000034798
1
1 Metal bracket fixing screw
 Remove the fixing screws of the metal brackets from the
pallet.
 Push the metal brackets a little towards the cylinder centre to
unhook them from the appliance feet.
 Pull the metal brackets out from underneath the appliance.
!
Material losses
Take note of the appliance's weight and centre of gravity.
 Slightly tip the appliance and carefully roll the appliance off
the pallet.
 Position the appliance in the final installation site.

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INSTALLATION
Installation
Minimum clearances
≥350≥350≥500≥350
≥400
≥400
≥350
≥350
≥350
≥350
≥350
≥350
D0000040627
 Maintain the minimum clearances.
!
Material losses
The appliance must be positioned vertically to avoid
damage.
The appliance has height-adjustable feet.
 Level the appliance horizontally using the height-ad-
justable feet.
D0000040663
10. Installation
!
WARNING Injury
Incorrect installation can lead to serious injury or materi-
al damage. Before any work, ensure sufficient clearances
for the installation.
Handle sharp-edged components carefully.
!
Material losses
Observe the lower application limit for the appliance. The
temperature of the air discharged from the appliance may
be lower than this value. If this air is admitted into the
building, this can lead to frost damage, e.g. on water
pipes.
You can operate the appliance in recirculation air mode or with
an air duct connection. You can have horizontal air routing (with a
side air intake and discharge), vertical air routing (with air intake
and discharge in the appliance cover) or a combination of the two,
thus ensuring flexible installation options and configurations in
the installation room. Accessories are required for the vertical air
intake and/or air discharge.
10.1 Air duct (optional)
Option: Fit the reducer to the side air connector
The side air duct connectors have a diameter of DN200 when
delivered. Standard delivery includes reducers for the air intake
and discharge should you wish to connect an air duct with a di-
ameter of DN160.
D0000040660
 Fit the reducer to the air connector by engaging the locking
hooks on the back of the reducer in the openings provided in
the air connector.
 Grip the small vanes on the reducer with your fingers.
 Turn the reducer clockwise until it audibly engages.
Air duct connection
Note
Connect the appliance and the air duct system using a
flexible method, e.g. a flexible ventilation pipe, to reduce
noise and vibrations.
 Connect a flexible 500 cm hose to the air duct.
The installation of a thermally insulated air hose is de- scribed as an example.

ENGLISH
www.stiebel-eltron.com WWK 221-301 electronic | 19
INSTALLATION
Installation
D0000047030
3
2
1
1 Air connector
2 Internal hose
3 External hose
 Pull the internal hose of the air hose slightly out of the exter-
nal hose and thermal insulation.
D0000047031
 Invert the internal hose halfway down the connector.
D0000047032
 Seal the transition from the internal hose to the connector
with self-adhesive thermal insulation tape.
D0000047033
 Pull the external hose and the thermal insulation below it
over the connector.
 Tuck the thermal insulation into the outer hose in such a way
that the thermal insulation is no longer visible.
D0000047034
 Seal the transition from the external hose to the connector
with self-adhesive thermal insulation tape.
D0000047035
 Secure the external hose with the hose clip to the connector.
D0000047036
 The air hose tends to sag because of its flexibility. Secure it
at intervals of approx. 1m.
 Insulate the air duct and all connections in line with insula-
tion standards if used for waste heat or outside air to prevent
condensation on these components.
!
Material losses
If the air duct and its connections are not insulated,
condensate may form on the air duct depending on the
appliance operating mode. Condensate can damage the
appliance. Dripping condensate can damage furniture or
floor coverings.
 Insulate the air duct, including the air connector to
the appliance, so that it is vapour diffusion-proof.

20|WWK 221-301 electronic www.stiebel-eltron.com
INSTALLATION
Installation
10.2 Water connection
!
Material losses
Carry out all water connection and installation work in
accordance with regulations.
!
Material losses
The corrosion protection provided by the anode can only
be guaranteed when the electrical conductivity of the do-
mestic hot water is within the limits stated in the chapter
"Specification/ Data table".
The following material combinations are approved for metal pipe-
work installations:
Cold water inlet DHW outlet
Copper pipe Copper pipe
Steel pipe Steel pipe or copper pipe
 Thoroughly flush the pipework before connecting the ap-
pliance. Foreign bodies, such as welding pearls, rust, sand
or sealant can impair the operational reliability of the
appliance.
!
Material losses
To protect the connections against corrosion the water
connection must be made with flat gaskets. The use of
hemp on connections is not permissible.
The insulated screw fittings included in the standard
delivery serve to prevent and insulate against cathodic
scaling due to highly conductive water.
D0000057018
2 31 4
1 Union nut
2 Insulating sleeve
3 Flanged pipe
4 Gasket
 Using the gaskets, insulating sleeves and union nuts provid-
ed, connect the flanged pipes included in the standard deliv-
ery to the "Cold water inlet" and "DHW outlet" connections.
 Check the insulated screw fitting for tightness.
Safety valve
The appliance is a sealed unvented DHW cylinder. Provide the
appliance with a pressure relief valve.
 Install a type-tested safety valve in the cold water supply
line. The response pressure of the safety valve must be below
or equal to the permissible operating pressure of the DHW
cylinder.
The safety valve protects the appliance against unacceptable ex-
cess pressure. The diameter of the cold water supply line must be
no greater than the diameter of the safety valve.
 Ensure that the expansion water escaping from the safety
valve can drip into a drain, e.g. a tank or funnel.
Ensure the drain cannot be shut off.
 Size the drain so that water can drain off unimpeded when
the safety valve is fully opened.
 Ensure that the discharge pipe of the safety valve is open to
atmosphere.
 Fit the discharge pipe of the safety valve with a constant
downward slope and in a room free from the risk of frost.
Pressure reducing valve
The maximum pressure in the cold water supply line must be at
least 20% below the response pressure of the safety valve. If the
maximum pressure in the cold water supply line is higher, install
a pressure reducing valve.
Drain valve
 Install a suitable drain valve at the lowest point in the cold
water inlet line.
DHW circulation
The heat losses incurred in the DHW circulation line and the elec-
trical power consumption of the circulation pump reduce the effi-
ciency of the system. The cooled water in the DHW circulation line
mixes with the cylinder content. Where possible, avoid installing
a DHW circulation line. Where that is not possible, the DHW cir-
culation pump must be controlled thermally or by time switch.
Thermal insulation
 Insulate the DHW line and valves against heat loss and to im-
prove energy efficiency in accordance with locally applicable
regulations.
 Insulate the cold water supply line to prevent condensate
forming.
10.3 WWK301 electronicSOL: Connection of an
external heat generator
!
Material losses
Even if an external heat generator is connected, do not
disconnect the appliance from the power supply as oth-
erwise it is not protected against frost and corrosion. The
power supply must not be interrupted even in winter,
when it is possible that DHW heating is only being pro-
vided via the external heat generator.