Test Symbols; Appliance Description; Heating The Dhw Cylinder - STIEBEL ELTRON WWS 20 Bedienung Und Installation

OPERATION

Appliance description

Material losses
!
Never cover the appliance. 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.
Material losses
!
Only operate the appliance when the DHW cylinder has
been filled.
Material losses
!
Keep the appliance installation site and the air draw-off
point free from air contaminated with oil or salt and from
explosive or corrosive substances (e.g. chlorine, sulphur,
ammonia).
2.4

Test symbols

See type plate. The type plate is located on the side of the ap-
pliance.
3. Appliance description
The appliance is a fully wired DHW heat pump in a hydraulic split
design. When combined with an externally connected DHW cyl-
inder, the appliance supplies DHW heating from several draw-off
points using renewable energy. Subject to the power supply and
user draw-off behaviour, the DHW cylinder is heated automatically
to the selected set temperature.
The appliance extracts heat from the ambient air at the air draw-
off point. This heat is used to heat up the water in the DHW cylinder
with added electric power. The amount of electrical energy and
time required to heat-up the DHW depend on the temperature of
the air drawn in.
Note
As the heat is drawn off from the supply air, the appliance
operates with a defined cooling capacity on the exhaust
air stream. In recirculation air mode, this can then cause
a temporary cooling of the installation room.
f When selecting the type and size of installation f
room, ensure that energy use is compensated over a
period of 24 hours and the lower application limit of
the appliance is not undershot. Please also observe
the following factors:
- Expected appliance runtime per day
- The resulting cooling energy
- Existing heat sources in the installation room
(e.g. freezer, tumble dryer, central heating)
- Heat flux from adjoining rooms
Note
When the intake air temperature drops, the appliance
output is reduced and the heat-up time is extended.
40 | WWS 20
The appliance is designed for indoor installation. It can be installed
as a recirculation air appliance and thus use the existing waste
heat from other heat sources in the installation room (e.g. wash-
ing machine, freezer). Alternatively the appliance allows you to
connect an air duct to route the supply air from another room or
to remove the exhaust air from the installation room. For times
when there is no DHW demand (compressor inactive), the fan
speed can be set separately.
Note
In heat pump mode (compressor active), the fan always
operates at a fixed rated speed set at the factory (see
chapter "Specification / Data table"), irrespective of the
fan speed set for operating without a compressor.
The appliance also extracts moisture from the ambient air, which
turns into condensate. The condensate is removed from the ap-
pliance via the condensate drain.
The appliance features an electronic control unit with LCD for set-
ting functions and operating modes.
Depending on which hydraulic cylinder connection is selected, an
immersion heater can be connected to the appliance control unit
and controlled from there.
External signal transmitters can be integrated via the built-in
switching input, for example a photovoltaic system to increase
the percentage of on-site power or an off-peak tariff signal.
Heat pump operating principle
A closed circuit within the appliance contains refrigerant (see
chapter "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 requires electrical energy. The energy (motor heat) is not lost,
but reaches the downstream condenser together with the com-
pressed refrigerant (plate heat exchanger). There, the refrigerant
indirectly transfers heat to the passing DHW. An expansion valve
then reduces the still prevalent pressure and the cycle starts again.
The appliance is fitted with a DHW primary pump at the factory.
Material losses
!
The internal primary pump should be started periodically
(every 20 hours for 3 seconds) to prevent it seizing up.
f Never interrupt the power supply to the appliance. f
f To switch off the appliance (standby mode), keep the f
power button pressed for approx. 2 seconds.
3.1

Heating the DHW cylinder

A temperature sensor captures the amount of heat in the DHW
cylinder. The water in the DHW cylinder is heated up if the amount
of heat is lower than that required to achieve the set temperature.
www.stiebel-eltron.com