STIEBEL ELTRON LWA 252 Instruction Manual

OPERATION AND INSTALLATION
CENTRAL VENTILATION APPLIANCE
»LWA252
» LWA 252 SOL

2 |LWA 252 | LWA 252 SOL WWW.STIEBEL-ELTRON.COM
CONTENTS
OPERATION
1. General information ____________________________________________3
1.1 Document information ____________________________________________ 3
1.2 Key to symbols ______________________________________________________ 3
2. Safety ____________________________________________________________3
2.1 Intended use_________________________________________________________ 3
2.2 Safety information _________________________________________________ 3
2.3 CE designation ______________________________________________________ 3
2.4 Test symbols_________________________________________________________ 3
3. Device description ______________________________________________4
3.1 Properties____________________________________________________________ 4
3.2 Function description _______________________________________________ 4
4. Operation ________________________________________________________4
4.1 Description of the user interface ________________________________ 4
4.2 Operation ____________________________________________________________ 5
4.3 Essential facts in brief _____________________________________________ 5
4.4 Display ________________________________________________________________ 5
4.5 Operating modes (control level 1)_______________________________ 5
4.6 Equipment menu (control level 2)_______________________________ 6
4.7 Adjustments at control level 2 ___________________________________ 6
4.8 Remote control RC 1 ______________________________________________12
5. Maintenance and care________________________________________ 12
6. What to do if... _______________________________________________ 12
6.1 . . . no hot water is available____________________________________ 12
6.2 . . . the safety valve of the cold water supply line is dripping
________________________________________________________________________ 12
6.3 . . . the condensate drain drips _________________________________ 12
6.4 . . . the red indicator in the fascia illuminates_______________ 12
6.5 . . . other faults occur_____________________________________________ 12
INSTALLATION
7. Safety __________________________________________________________ 13
7.1 General safety instructions ______________________________________ 13
7.2 Instructions, standards and regulations ______________________ 13
7.3 Ventilation system_________________________________________________ 13
8. Device description ____________________________________________ 14
8.1 Function _____________________________________________________________ 14
8.2 Design operation __________________________________________________ 14
8.3 Standard delivery__________________________________________________ 14
8.4 Special accessories________________________________________________ 14
9. Installation ____________________________________________________ 15
9.1 Installation conditions ____________________________________________ 15
10. Installation ____________________________________________________ 15
10.1 Handling_____________________________________________________________ 15
10.2 DHW connection __________________________________________________ 15
10.3 Condensate drain__________________________________________________ 16
10.4 Solar connection (LWA 252 SOL)________________________________ 16
10.5 Installing extract air and discharge air pipes________________ 16
10.6 Power supply _______________________________________________________ 17
11. Commissioning________________________________________________ 19
11.1 Checks before commissioning __________________________________ 19
11.2 Commissioning overview, control unit LWM ________________ 20
11.3 Commissioning the LWM control unit _________________________ 21
11.4 Commissioning report____________________________________________ 23
12. Troubleshooting_______________________________________________ 24
13. Maintenance, cleaning and safety equipment_____________ 24
13.1 Maintenance________________________________________________________ 24
13.2 Cleaning _____________________________________________________________ 24
13.3 Safety equipment__________________________________________________ 24
14. Specification___________________________________________________ 26
14.1 Wiring diagram ____________________________________________________ 26
14.2 Specification________________________________________________________ 27
14.3 Fan curve____________________________________________________________ 28
14.4 Setting air volume flow __________________________________________ 28
14.5 Connection dimensions and variations _______________________ 29
GUARANTEE
ENVIRONMENT AND RECYCLING

OPERATION
GENERAL INFORMATION
ENGLISH
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1. General information
1.1 Document information
The chapter Operation is intended for the appliance user and the
heating contractor.
The chapter Installation is intended for heating contractors.
Please read
Read these instructions carefully before using the
appliance and retain them for future reference. If the
appliance is passed on to a third party, please hand
these instructions to the new user.
1.2 Key to symbols
Symbols in this documentation:
In these instructions you will come across symbols and highlights.
These have the following meaning:
Risk of injury
Information concerning possible risk of injury.
Danger of electrocution!
Risk of scalding or burning
!Possible damage
Information concerning damage to the appliance,
environmental damage or material losses.
Please read
Text next to this symbol is particularly important.
» The "»" symbol indicates that you should do something. The
action you need to take is described step by step.
2. Safety
2.1 Intended use
The appliance is a complete system with heat recovery for
centralised ventilation and extraction, as well as for centralised
DHW heating.
Any other use beyond that described shall be deemed inappropriate.
Observation of these instructions is also part of the correct use of
this appliance. Any modifications or conversions to the appliance
void all warranty rights.
2.2 Safety information
Observe the following safety information and regulations.
All steps up to the complete commissioning of this appliance must
only be carried out by qualified contractors.
Contractors are responsible for adherence to all currently
applicable regulations during installation and commissioning.
Operate the appliance only when fully installed and with all safety
equipment fitted.
Never adjust the ventilation and extract air valves inside the
rooms. These have been adjusted during commissioning.
Never make any modifications to the internal equipment electrics
or controls.
Risk of scalding
There is a risk of scalding at outlet temperatures in
excess of 43 °C.
Risk of injury
Where children or persons with limited physical,
sensory or mental capabilities are allowed to control
this appliance, ensure that this will only happen
under supervision or after appropriate instruction by
a person responsible for their safety.
Children should be supervised to ensure that they
never play with the appliance.
Danger of electrocution!
Never splash the appliance with water or other liquids.
!Please note
Never change any system-specific settings at the
control unit. Your contractor has set the control unit
to match the local conditions for your building and
your individual requirements. The system-specific
parameters are protected by a CODE check so they
cannot be unintentionally modified.
The parameters that serve to match the appliance to
your personal requirements are not protected by a
CODE check.
2.3 CE designation
The CE designation shows that the appliance meets all essential
requirements:
— Electromagnetic Compatibility Directive
(Council Directive 89/336/EEC)
— Low Voltage Directive (Council Directive 73/23/EEC)
2.4 Test symbols
See type plate
The type plate is located an the l.h. side of the appliance.

OPERATION
DEVICE DESCRIPTION
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3. Device description
3.1 Properties
The air|water heat pump recovers waste heat from the extracted
air via a duct system. This energy is transferred to the DHW. The
cooled air is discharged to the outside.
Outside wall valves channel in fresh air, that replaces air expelled
by the heat pump.
Special features of the LWA 252 SOL
This appliance version has an additional indirect coil integrated
into the DHW cylinder that is designed for DHW heating with solar
energy.
3.2 Function description
3.2.1 Heat pump operation
This is the standard operating mode, to which the limits of scope
of the heat pump apply (see: Specification). To heat or reheat
the cylinder content of approx. 300 litres of water from 15 °C to
55 °C, in accordance with EN 255 part 3, the appliance requires
the following:
WHeat-up WReheat -Extract air Frel Vair
11 h 5 . 5 h 2 0 °C 4 0 % 1 25 m 3/h
10 h 5 . 0 h 2 0 °C 4 0 % 2 5 0 m 3/h
Electric booster heater
When there is a higher DHW demand or when the appliance
heat pump has been switched OFF for a longer period, and you
require hot water quickly, you can accelerate the heat-up process
by means of an electric booster heater. For this, adjustments are
required at the third operating level. These must only be carried
out by a heating contractor.
To save energy, the electrical booster heater only heats the top
third of the cylinder (approx. 100 litres). This takes approx. 3 hours.
3.2.2 Ventilation operation
The appliance fan starts when the mains plug is inserted into
the socket. It cannot be switched off separately at the appliance.
3.2.3 Operation outside the scope of applications
Extract air temperature below 15 °C:
Subject to the relative humidity and the flow rate, the evaporator
begins to build up hoar frost at an ambient temperature of below
15 °C.
The appliance is stopped by a frost protection function.
The appliance will restart automatically after expiry of the defrost
time.
Extract temperature in excess of 30 °C:
The heat pump will be stopped by safety equipment at extract air
temperatures in excess of approx. 30 °C. The heat pump will be
re-started automatically after a brief cooling down period. The
heat pump will be stopped again, if the extract air temperature
is still higher than 30 °C.
!Please note
Take appropriate steps to prevent the extract air temperature
rising above 30 °C.
4. Operation
4.1 Description of the user interface
Room temperature
Operating modes/ventilation
DHW temperature
Solar temperatures
Day/time
Holiday/party program
Info temperatures
Ventilation program
DHW program
Commissioning
VENTILATION
12456 3
26_04_01_0436
1 Rotary selector
2 Rotary selector Reset / Auto
3 Appliance menu
4 Programming key
5 Programming indicator
6 Control flap (open)
System status display
VENTILATION
26_04_01_0437
1
2
5
63
4
1 Heat pump operation
2 Fan operation
3 Defrosting
4 DHW booster heater
5 Solar circuit pump
6 Maximum cylinder temperature

OPERATION
OPERATION
ENGLISH
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4.2 Operation
The operation is split over three control levels. Control levels 1
and 2 are accessible to users and contractors alike. Control level
3 is reserved for qualified contractors:
Control level 1 (control flap closed)
Here, the operating mode, such as standby operation, programmed
operation, constant day and setback operation of the DHW program
can be adjusted.
Control level 2 (control flap open)
Here, system parameters, such as DHW temperatures, etc. can
be adjusted.
Control level 3 (for contractors only)
This level is access protected by a code and should only be used
by a contractor. Here, you can determine the specific details
regarding the heat pump and the heating system.
4.3 Essential facts in brief
Settings
All settings follow the same pattern:
Opening the control flap toggles the manager into programming
mode. An indicator symbol is shown at the bottom of the display
at system parameter ROOM TEMP. Turning the rotary selector
allows you to move the indicator to the system parameter you
want to change.
To change the system parameter, press . Whenever the red
indicator above illuminates, you can modify the current value
by turning rotary selector . Press again, the indicator then
extinguishes and the new set value has been saved. You can
modify further values for this parameter by pressing , if the red
indicator above has not been extinguished after saving. The
programming step can only be terminated when the red indicator
has gone out.
Terminating the programming process
You can terminate the programming process after entering
and saving the required parameter changes by closing the
control flap. However, if you want to make further changes,
turn the rotary selector until the display shows BACK,
then press . This will return you to the previous level.
Closing the control flap with illuminated indicator above
returns the manager to its original position. The modified value
will then not be saved.
Please read
During commissioning, a system check will be
implemented, e.g. all sensors that are currently
connected are displayed upon request. Sensors
not connected before the system went 'live' are not
registered by the manager and are therefore not
displayed. The indicator symbol skips such system
parameters.
Example: The system parameter SOLAR TEMP will be skipped if,
at commissioning, the solar collector sensor was not connected.
Values for these parameters, therefore, cannot be programmed.
4.4 Display
7
4
26_03_01_0434
24
12
18 6V
C
C
2986531
14 13 12 11 10
1 Heating times for DHW (black)
2 14-digit plain text display
3 Day mode
4 Fan running
5 Compressor running
6 Fan stages (control level 1)
Switching time pair for ventilation and DHW operation
(control level 2)
7 Booster in operation
8 Defrosting
9 Setback mode
10 Constant setback mode
11 Constant day mode
12 Automatic mode
13 Standby mode
14 Fault message (flashing)
4.5 Operating modes (control level 1)
The operating modes are changed by turning the rotary selector
with the control flap closed.
Standby mode
Frost protection is activated for DHW operation. The display
indicates frost protection when the flap is closed. Ventilation runs
in setback mode.
Application: During holidays.
At control level 2 under parameter VENTILATION, ventilation can be
completely stopped. For this, adjustments are required on the
third operating level. These must only be carried out by a heating
contractor.

OPERATION
OPERATION
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Automatic mode
DHW heating in accordance with a time switch program.
Changeover between day temperature and setback temperature.
When flashing, the heat pump idle time is counting down.
Application: To reduce the DHW temperature during the day,
so that the maximum solar yield can be achieved with the solar
version.
Constant day mode
DHW heating is held constantly at the day temperature.
Application: For maximum DHW convenience.
Constant setback mode
DHW heating is held constantly at the setback temperature.
Fault message (flashing)
Indicates faults in the system.
4.6 Equipment menu (control level 2)
Select the required parameter with the rotary selector.
Example: VENTILATION
VENTILATION
Under parameter ROOM TEMP you can check the current
temperature of the assigned reference room on the display subject
to the connection of remote control RC 1 with room temperature
sensor.
With parameter VENTILATION, you can adjust the operating modes
for ventilation operation.
With parameter DHW TEMP, you can allocate a set day and night
temperature to the temperature inside the DHW cylinder.
With parameter SOLAR TEMP you can assign the temperatures for
solar operation.
You can adjust the time and summertime with the parameter
TIME/DATE menu item. At the factory, summertime is set to begin
on 25 March and to end on 25 October.
You can set holiday programs with the HOLIDAY parameter. In the
holiday program, the heat pump system operates in setback mode.
You can extend the day mode by a few hours with the PARTY
parameter.
In parameter TEMPERATURES, you can scan the sensor temperatures
of the ventilation and heat pump system, comparing set with
actual temperatures.
In parameter VENTILAT PROG you can adjust the times for the day
and setback temperatures for the ventilation program.
In parameter DHW PROGRAM you can adjust the times for the day
and setback temperatures for DHW heating.
During COMMISSIONING, you need to determine the settings of control
level 2 and the system-specific parameters. These parameters are
adjusted at control level 3 by your heating contractor, access to
which is protected by code.
Your contractor needs to check all parameters in sequence, and
enter all selected values into the column (system value) provided
in the commissioning report.
4.7 Adjustments at control level 2
To make any adjustments at control level 2, you must open the
control flap.
4.7.1 Room temperature
Under parameter ROOM TEMP the current temperature of the
assigned reference room is displayed, subject to the connection
of the remote control RC 1 with the room temperature sensor. The
ROOM TEMP parameter will only be displayed if the remote control
RC 1 is connected.
ROOM TEMP
ACTUAL ROOM T
BACK
NIGHT COOLING
Connecting the remote control RC 1 and the outside temperature
sensor AFS 2 enables you to cool down your residence over night.
For this, your contractor needs to set parameter NIGHT COOLING at
control level 3 to ON.

OPERATION
OPERATION
ENGLISH
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4.7.2 Ventilation
With parameter VENTILATION, you can adjust the operating modes
for ventilation operation.
When the required operating mode is shown, press PRG; the
operating mode is then set.
PRG
PRG
PRG
PRG
24
12
18 6
24
12
18 6
24
12
18 6
24
12
18 6
24
12
18 6
PRG
PRG
PRG
VENTILATION
OPERATION MODE
STANDBY
AUTOMATIC
DAY MODE
SETBACK MODE
party
OPERATION MODE
BACK
4.7.3 DHW temperature
With parameter DHW TEMP, you can allocate a set day and night
temperature to the temperature inside the DHW cylinder.
DHW TEMP




ACTUAL DHW T
BACK

OPERATION
OPERATION
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4.7.4 Solar temperatures
You can set the parameters for solar operation under the
SOLAR TEMP parameter.
A sensor is installed in the appliance that measures the temperature
in the lower region of the DHW cylinder. This actual value will be
taken into consideration for the start condition of the solar circuit
pump.
Parameter SOLAR DIFFEREN determines by what amount the
collector temperature must be above the water temperature in
the lower region of the cylinder to start the solar circuit pump. If
the water temperature in the lower region of the cylinder reaches
the value selected under MAX SOLAR TEMP, then the solar circuit
pump starts.
PRG
PRG
SOLAR TEMP
SOLAR DIFFEREN
SOLAR DIFFEREN
MAX SOLAR TEMP
BACK
MAX SOLAR TEMP
4.7.5 Time and date
You can adjust the time and summertime with the TIME/DATE
parameter.
At the factory, summertime is set to begin on 25 March and to
end on 25 October.
SET CLOCK
TIME
TIME
YEAR
MONTH
DAY
SET CLOCK
SUMMER TIME
BACK
TIME/DATE

OPERATION
OPERATION
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4.7.6 Holiday and party program
In the holiday program, the heat pump system runs in setback
mode, and frost protection for DHW heating is enabled. Holiday
mode is displayed when the flap is closed. The holiday program is
set under the HOLIDAY parameter. For the start of the holidays, the
year, month and day are entered; also enter the year, month and
day for the end of the holidays. The start time is always 00:00 h and
the end time 23:59 h of the date entered. After the holiday period
has expired, the heat pump system operates again in accordance
with the previous heating and DHW program.
You can extend the day mode by a few hours with the PARTY
parameter. Party mode is displayed when the flap is closed.
For example, if the heating program would normally switch to
setback mode at 22:00 h and you have set party mode for 2 hours,
then setback mode would not start until midnight.

HOLIDAY
YEAR START
MONTH START
DAY START
YEAR END
MONTH END
DAY END
HOLIDAY
PARTY
BACK
4.7.7 TEMPERATURES
Under parameter TEMPERATURES, you can scan the sensor
temperatures of the ventilation system.
TEMPERATURES
OUTSIDE TEMP
BACK
Actual or set temperatures will not be displayed if the corresponding
sensor is not connected.

OPERATION
OPERATION
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INFO LWM Description
OUTDOOR TEMP Outside temperature
(will only be displayed if an outside temperature
sensor is connected)
ROOM TEMP Actual room temperature
(will only be displayed if the remote control RC 1
is connected)
ACTUAL DHW T Actual DHW temperature
SET DHW TEMP Set DHW temperature
EVAPOR TEMP Actual evaporator temperature
EVAPOR MIN Evaporator frost protection temperature
COLLECTOR Solar collector temperature
(operation with differential controller)
CYLINDER BELOW DHW cylinder temperature, bottom
(operation with differential controller)
CYLINDER MAX Maximum DHW cylinder temperature
(operation with differential controller)
4.7.8 Ventilation program
Under parameter VENTILAT PROG, you can set the times for
VENTILATION.
You can adjust the VENTILATION as follows:
— For each individual day of the week (Monday, ..., Sunday)
— Monday to Friday (Mo - Fr)
— Saturday and Sunday (Sa - Su)
— The whole week (Mo - Su)
You can adjust three switching time pairs (I, II, III) for each of
these options.
Exception: You will need two switching time pairs, if you want to
ventilate from 22:00 h until 06:00 h the following day.
This determines when and how often the appliance should operate
in ventilation mode. You will already have set the corresponding
operating mode for the ventilation program under system
parameter VENTILATION.
Example:
You want to ventilate your residence daily at three different times,
i.e. from 05:15 h until 08:00 h and then from 10:45 h to 14:00 h,
finally from 17:30 h to 21:45 h.
PRG
24
12
18 6
24
12
18 6
24
12
18 6
24
12
18 6
24
12
18 6
24
12
18 6
PRG
PRG
PRG
PRG
PRG
PRG
PRG
VENTILAT PROG

START
STOP
START
STOP
START
STOP

BACK

OPERATION
OPERATION
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4.7.9 DHW program
Under parameter DHW PROGRAM you can adjust the times for the
day and night temperatures for DHW heating.
You can adjust your DHW heating as follows:
— for each individual day of the week (Monday, ..., Sunday)
— Monday to Friday (Mo - Fr)
— Saturday and Sunday (Sa - Su)
— the whole week (Mo - Su)
You can adjust three switching time pairs (I, II, III) for each of these
options. Exception: You will need two switching time pairs, if you
want to heat DHW from 22:00 h until 06:00 h the following day.
This determines when and how often the appliance should heat
DHW. You will already have selected the corresponding set values
for day and night mode under the DHW TEMP system parameter.
Example:
You want to heat up DHW daily at two different times, i.e. from
22:00 h until 06:00 h the following day, and then again from 08:00 h
until 09:00 h.
The day begins at 00:00 h; therefore begin programming for this
example at 00:00 h. The first switching times pair runs from 00:00
until 06:00 h. The second switching times pair runs from 08:00 h
until 09:00 h. The third switching times pair runs from 22:00 h
until 23:59 h.
DHW PROGRAM

DHW START
DHW STOP
DHW START
DHW STOP
DHW START
DHW STOP

back
DHW PROGRAM

OPERATION
MAINTENANCE AND CARE
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4.8 Remote control RC 1
26_04_01_0444
The room temperature is captured by the remote control RC 1 .
A night cooling can be programmed at control level 3 subject to
connection of an outside temperature sensor AFS 2.
The fan stages can also be changed manually.
IContinuously fan stage 1
Programming mode
III Continuously fan stage 3
5. Maintenance and care
!Risk of damage
Maintenance work, such as checking the electrical
safety, must only be carried out by a heating
contractor. Protect the appliance from dust and dirt
ingress during building work.
A damp cloth is sufficient for cleaning all plastic and sheet steel
parts. Never use abrasive or corrosive cleaning agents.
Check the condensate drain at least once every month (visual
inspection). Remove contaminants and blockages immediately.
6. What to do if...
6.1 . . . no hot water is available
» Check the fuse/circuit breaker in your fuse box. If it has blown/
tripped, replace/reset the fuse/MCB. Notify your contractor if the
fuse/MCB blows/trips again.
» Check whether the air inlet and air discharge are unobstructed
or whether a filter is blocked that may be incorporated.
The thermoswitch trips out or the safety pressure limiter switches
the compressor OFF if the compressor is overloaded due to
excessive ambient temperature, excessive extract temperature
(>30 °C), or because of a fault in the refrigerant circuit. The
thermoswitch automatically switches itself ON again.
!Risk of damage
The safety pressure limiter must only be reset by
your contractor after he has removed the cause of
the relevant fault.
6.2 . . . the safety valve of the cold water supply
line is dripping
This may occur during the heat-up phase and is completely normal
as water expands when heated.
6.3 . . . the condensate drain drips
After the initial commissioning or after prolonged idle times it
may occur that air is sucked in through the condensate drain. If
the pump runs for a few hours, the siphon in the condensate drain
will fill with condensate, which prevents an ingress of air.
6.4 . . . the red indicator in the fascia illuminates
In this situation the safety pressure limiter has responded and
may only be reset by your contractor.
6.5 . . . other faults occur
Telephone your contractor. To facilitate and speed up your enquiry,
please provide him with the number from the type plate (no.
000000-0000-000000). The type plate is located on the front at
the top on the right or left hand side of the casing.

ENGLISH
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INSTALLATION
SAFETY
7. Safety
7.1 General safety instructions
All required steps up to and including commissioning must be
carried out by a qualified contractor. During this process, these
installation instructions must be observed.
We guarantee trouble-free operation and operational reliability
only if the original accessories and spare parts intended for the
appliance are used.
Observe local building regulations, commercial and fire regulations
as well as regulations and laws concerning emissions.
For example in Germany these are:
TA-Lärm: Technical instructions to protect against noise emissions
EnEV: Energy Savings Order
Observe the requirements of the local water supply utility.
7.2 Instructions, standards and regulations
7.2.1 Electrical installation
!Risk of damage
The specified voltage must match the mains voltage.
Observe the type plate.
Danger of electrocution!
Carry out all electrical connection and installation
work in accordance with national and regional
regulations.
Danger of electrocution!
Always switch OFF the power to the appliance before
cleaning and maintenance.
DIN VDE 0100: Regulations for the installation of HV systems with
rated voltages up to 1000 V.
VDE 0701: Regulations regarding the repair, modification and
testing of used electrical equipment.
DIN-EN 60335 part 2-40: Safety of electrical equipment for
domestic use and similar purposes.
VDE 0298-4: Recommended values for the electrical capacity
of cables and leads for fixed routing in and to buildings and of
flexible cables.
TAB: Technical connection conditions for connections to the LV
mains.
7.2.2 Water installation
DIN 1988, DIN EN 806: Technical rules for DHW installations
TRD 721 - Safety equipment to prevent excess pressure - safety
valves.
We approve steel, copper or plastic pipework for the cold water
line.
7.2.3 Ventilation installation
DIN 1946 T1, T6 - Ventilation and air conditioning
DIN EN 779 - Particle air filter for general ventilation and air
conditioning
VDI 2087 - Air ducts
7.2.4 Refrigerant circuit
EN 378: Safety and environmental requirements, or local
regulations.
Safety datasheet of the refrigerant.
7.3 Ventilation system
Safety information
If the building contains combustion equipment (tiled stoves,
fireplaces, wall mounted gas boilers etc.), ensure that such
combustion equipment is supplied with combustion air separate
from the ventilation equipment (check with your local flue gas
inspector, as requirements vary across regions and countries).

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INSTALLATION
DEVICE DESCRIPTION
8. Device description
8.1 Function
Extract air is drawn in by the extract air fan and channelled
through the evaporator to the outside.
The energy made available by the heat pump is transferred in a
separate condenser to the DHW system.
Where there is a high DHW demand, the DHW is heated by an
electric immersion heater.
26_03_01_0254
1 Extract fan
2 Compressor
3 Immersion heater
4 Heat exchanger
5 Condenser
6 DHW cylinder
7 Non-return valve
8 Filter dryer
9 Evaporator
10 Expansion valve
I Extract air
II Discharge air
III Discharge air (optional)
IV DHW
V Circulation
VI Cold water
8.2 Design operation
This appliance is designed for ventilation in apartments and
detached houses as well as centralised DHW heating for several
domestic draw-off points.
Never:
— Use extracted air loaded with grease, explosive gases, dust or
adhesive aerosols
— Connect cooker hoods to the ventilation system
— Heat liquids other than potable water
Never install the appliance:
—Outside
— In rooms where there is a risk of frost
— In wet rooms, such as bathrooms
Never operate the appliance:
— Without discharge air and extract air ducts
— Without decentralised inlet air elements
— Without ventilation function
— With an empty cylinder
— Whilst building work is in progress
8.3 Standard delivery
— Operating and installation instructions
— PT 1000 solar collector sensor (only with the LWA 252 SOL)
Part no. 165818
8.4 Special accessories
Description Part no.
Outside temperature AFS 2 165339
Remote control with room sensor RC 1 170328
External wall air outlet 073184

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INSTALLATION
INSTALLATION
9. Installation
9.1 Installation conditions
The system may be installed in any rooms apart from wet areas.
The room in which the appliance is to be installed must meet the
following conditions:
— The room must be free from the risk of frost.
— The floor must have sufficient load-bearing capacity. On top of
the weight of the appliance, there will be 300 l of water.
— The substrate must be solid and permanent.
— When installing the appliance inside a boiler room, ensure
that the boiler operation will not be impaired.
— The available floor area in the installation room must be at
least 2 m² because of the volume of refrigerant. The volume
must not be less than 4 m³.
— Never operate the appliance in rooms at risk from explosion
due to dust, gases or vapours.
— The extract air supplied to the equipment must not be lower
than +15 °C, otherwise the evaporator would ice-up. Also, the
lower the extracted air temperature, the lower the heat pump
efficiency.
Never restrict the available space around the appliance through
walls or ceilings closer than shown in the diagram.
Dimensions in mm
26_04_01_0251
10. Installation
10.1 Handling
To protect the appliance against damage, it should be transported
vertically inside its packaging. Where space is restricted, you may
also move the equipment tipped backwards at an angle.
10.1.1 Positioning
» Undo the four screws from the non-returnable pallet.
» Remove the washers.
» Before removing the appliance from the pallet, remove the anti-
vibration mounts from the pack supplied, and insert into the
appliance.
» Level the appliance horizontally by adjusting the anti-vibration
mounts.
10.2 DHW connection
The appliance is supplied (in the pack bag) with elbow plug-in
fittings to facilitate an easy connection to the DHW system.
Fitting the plug-in connector
The plug-in connectors are equipped with a retainer with stainless
steel serrations and an O-ring for sealing. In addition, they are
designed with the "Twist and secure" function. By simply turning
the screw cap manually, the pipe is secured in the connector, and
the O-ring is pushed against the pipe to seal it.
Making the connection
The fitting must be in its relaxed state before inserting the pipe.
In this position, there is a small gap between the screw cap and
fitting body.
Gap between the screw cap and the
body (relaxed position)
Push the pipe past the O-ring until it bottoms out inside the
connector. Tighten the screw cap until it meets the casing. This
presses the O-ring against the pipe and secures the connector.

16 |LWA 252 | LWA 252 SOL WWW.STIEBEL-ELTRON.COM
INSTALLATION
INSTALLATION
Releasing the connection
Turn the screw cap back until a small gap appears. Turn the
retainer back by hand and hold it in position. The pipe can now
be pulled out again.
If the elbow plug-in fittings are not used, make the connection
with flat gaskets for anti-corrosion reasons. The use of hemp on
connections is not acceptable.
Insulate the DHW line in accordance with local regulations.
Accurately maintain the order of fittings on the cold water side.
Flush the line prior to installation.
2326 5 4 1
7
26_04_01_0456
1 Drain & fill valve
2 Straight-through shut-off valve
3 Pressure gauge test connector
4 Non-return valve
5 Inspection valve
6 Pressure reducing valve
7 Safety valve
Install a drain valve at the lowest point of the cold water supply
line.
Install a pressure reducing valve when the water pressure is
higher than 0.48 MPa.
Special measures are required at a water pressure in excess of
1 MPa.
A 0.6 MPa safety valve must be installed on site.
Blow-off line:
— Size the blow-off line for a fully opened safety valve. The
blow-off aperture of the safety valve must remain open to the
atmosphere.
— The safety valve's blow-off line should be installed with a
constant downward incline.
— Observe the information in the "Safety valve" installation
instructions.
DHW circulation line
The heat losses incurred in the circulation line and the electrical
power consumption of the circulation pump reduce the efficiency
of the system. The cooled water in the circulation line mixes with
the cylinder content.
Where possible, avoid installing a circulation line. Where that is
not possible, control the DHW circulation pump thermally or by
time switch.
10.3 Condensate drain
For the condensate drain, a hose is fitted to the defrost pan
connector.
!To ensure the condensate drains perfectly, never kink
the hose. If necessary, create a loop. Route the hose
with an adequate slope.
After installing, check the condensate line for function and
tightness.
Route the condensate into a drain. When doing so, ensure the
drain is adequately ventilated (e.g. free outlet into a siphon). Use
a condensate pump if there is insufficient fall.
10.4 Solar connection (LWA 252 SOL)
Pipe bends with union nuts are supplied with the appliances that
are fitted with internal coils, to enable an easy connection to the
solar thermal system.
10.5 Installing extract air and discharge air pipes
In line with DIN 24145, folded spiral pipes NW 160 are envisaged
for connection to this appliance.
Insulate the extract air line to prevent heat loss in case it is routed
through rooms that are colder than those from which the air is
extracted (e.g. attics, cellars, garages and false ceilings). Fit the
extract air pipe to the connector on the l.h. side of the appliance
so that it is neither subject to stresses nor torque.
Fit the discharge air pipe either to the r.h. side or the top of the
equipment so that neither stresses nor torque are applied to the
equipment. Insulate the discharge air duct against condensation
with a vapour-proof layer.

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INSTALLATION
INSTALLATION
The discharge air connector is located at the top of the equipment
as standard. The following steps are necessary for conversion:
» Isolate the appliance from the power supply by pulling the power
plug.
26_04_01_0443
» Removing the cover from the top of the appliance.
» Undo the 6 self-tapping screws from the r.h. upper side panel.
» Tip the side panel approx. 10 degrees to the side and remove
the EPS profile that faces to the front of the appliance upwards.
» Pull the second EPS profile about 20 mm in the direction of the
appliance front and then remove it upwards by tipping the side
panel by approx. 10 degrees.
» Remove the cover panel from the side panel.
» Remove the discharge air connector from the appliance cover.
» Fit the cover panel to the appliance cover.
» Fit the discharge air connector from the inside to the side panel.
» Install the EPS profiles in reverse order, so that the airway now
points towards the appliance side panel.
» Secure the r.h. top side panel with 6 self-tapping screws.
» Fit the appliance cover with 4 self-tapping screws.
For anti-vibration separation and service reasons, connect the
LWA to extract and discharge air ducts with about 1 m length of
flexible pipe each.
Also insulate these lines.
!Risk of damage
When operating a dryer or a cooker hood that extracts
air, ensure also, that a sufficiently large air flow rate
is supplied to that equipment, independent of the
ventilation equipment.
10.6 Power supply
The appliance is supplied fully wired, and should be plugged into
an accessible earthed mains power socket.
Danger of electrocution!
Isolate the appliance from the power supply by pulling
the power plug prior to commencing work on the
control panel.
Only qualified electricians must carry out the connection work.
Route power supply and control cables separately.
Observe VDE 0100 [or local regulations] and the regulations of your
local power supply utility.
The terminals are located beneath the lower front fascia, top right
hand side. When removing the front fascia ensure that the earth
cable is not ripped off the front fascia. If necessary, remove the
cable from the blade terminal.
26_04_01_0446
14
13
4
3
2
1
PE
X1
5
6
7
L
8
N
9
10
11
12
N
L
Solarkreis-
pumpe

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INSTALLATION
INSTALLATION
26_04_01_0447
Kleinspannung
Fernb. 1
Fernb. 2
T-Kollek.
T-Kollek.
T-Außen.
T-Außen.
26_04_01_0249
26_04_01_0250
When replacing the front fascia ensure that the earth cable is
correctly connected.
Route all connecting cables and sensor leads through the entries
in the back panel (see chapter "Connection dimensions and
variation in sizes").
10.6.1 Connection, remote control RC 1
1 2 3
REM CON. 1 REM CON. 2
26_04_01_0464
Fitting outside temperature sensor AFS 2
The outside temperature sensor should be freely
exposed to the elements. Never fit it above windows,
doors, light wells or air ducts, and never subject it
to direct insolation.
Install the outside temperature sensor on a north
or north-eastern wall.
The minimum height above the ground is 2.5 m,
and 1 m to the side of windows and doors.
» Remove the cover of the sensor enclosure.
» Secure the sensor enclosure to the wall using the screw provided.
» Route the sensor cable through the cable entry located on the
upper edge of the back panel.
» Connect the sensor lead to the outside temperature sensor.
» Place the cover on the sensor enclosure so that it clicks audibly
into place.
10.6.2 Fitting the collector sensor
The collector sensor is included in the separate pack
for LWA...SOL appliances.
Dimensions: Diameter 6 mm, lead length 2 m
(silicone lead)
Insert the collector sensor into the collector
sensor well.
The correct connection of the collector sensor is crucial to the
correct function of a solar thermal system. The sensor on our
collectors is installed on the last collector, viewed in the flow
direction of the heat transfer medium.
» Fit and seal-in the collector sensor well on the collector.
» Coat the collector sensor with heat conducting paste and insert
it into the sensor well until it bottoms out.
Provide thermal insulation for the collector sensor well and the
roof outlet, which must be tightly sealed and UV resistant.

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INSTALLATION
COMMISSIONING
Fitting the collector sensor
1
3
5
4
2
26_03_01_0192
1 Heat conducting paste
2 Temperature sensor
3 Sensor well
4 Thermal insulation
5 Flow direction of the heat transfer medium
Sensor resistance values
The sensors integrated in the appliance, the sensors provided and
the outside temperature sensor are PTC sensors. The collector
sensor is a PT 1000 sensor.
PTC sensor resistance values
Temperature in °C Resistance in Ω
– 20 1367
– 10 1495
01630
10 1772
20 1922
25 2000
30 2080
40 2245
50 2417
60 2597
70 2785
80 2980
90 3182
100 3392
PT 1000 sensor resistance values
Temperature in °C Resistance in Ω
– 30 843
– 20 922
– 10 961
01000
10 1039
20 1078
30 1117
40 1155
50 1194
60 1232
70 1271
80 1309
90 1347
100 1385
110 1423
120 1461
!When measuring with a multimeter, the resistance
values serve only to identify faulty or incorrect
sensors. Measuring with a multimeter is too imprecise
to test for accuracy.
11. Commissioning
!Only approved contractors may commission this
equipment and instruct the operator in its use.
» Commission the system in accordance with these operating
and installation instructions. Our customer service can provide
commissioning support, which is chargeable.
11.1 Checks before commissioning
Ventilation system
— Have the air ducts been installed and insulated correctly?
Cylinder
— Has the cylinder been filled (hot tap open until water flows
out)?
— Has a pressure reducing valve been installed if the water
pressure is above 5 bar?
Temperature sensor
— Have all temperature sensors been correctly placed and
connected?
!Operating the ventilation appliance is not permitted
whilst building work is still in progress.

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INSTALLATION
COMMISSIONING
11.2 Commissioning overview, control unit LWM
(Control level 3)
No. Parameter (shown in the display)
COMMISSIONING
1ENTRY CODE
2CHANGE CODE
3LANGUAGE GERMAN --- ENGLISH
4CONTRAST
5DISPLAY OUTDOOR TEMP DAY DHW TEMP
6EVAPOR MIN
7DHW ONCE ON / OFF
8PASTEUR TEMP
9PASTEURISATION 00 / 01 / 02
10 DHW HYSTERESIS
11 FLOW RATE STANDBY SETBACK STANDARD PARTY MINIMUM
12 FROST PROTECT BACK
13 NIGHT COOLING ON / OFF
14 QUICK START
15 RELAY TEST SOLAR PUMP IMM HEATER
16 LCD TEST
17 LWM SOFTWARE
18 ANALYSIS
19 HP RESET ON / OFF
20 RUNTIME COMP
21 STARTS COMP
22 RUNTIME POWER
23 STARTS POWER
24 RUNTIME SOLAR
25 STARTS SOLAR
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