Installation Instructions; Unit Structure; Important Notes; Brief Description - STIEBEL ELTRON DEL 18 Si Gebrauchs- Und Montageanweisung

2. Installation instructions

2.1 Unit structure A - M
1 Thermostat
2 Control unit
3 Display with temperature indication
4 Cover
5 Rear wall - lower part
6 Hot water screw connection
7 Cold water screw connection (3-way
isolating valve)
8 Rear wall - upper part
9 Terminal block
10 Securing screw - module carrier
(service)
11 Power electronics circuit board
12 Safety switch with reset button (blue)
13 Heating element
14 Electronics control circuit board
15 LED for operation and fault indication
(see „4. Fault rectification")
16 Plug-in position of thermostat fly-lead
connector
17 Securing screw for unit
18 Plug for thermostat fly-lead
19 Unit securing arrangement - bottom
20 Electrical lead, concealed in the lower
part of the unit
21 Dimension for „wall flush fitting"
installation
22 Electrical lead, concealed in the upper
part of the unit
23 Unit mounting bracket
24 Unit securing arrangement at top, for
new installation
25 Knock-out point for unit mounting
bracket supplied
26 Knurled knob for rear wall alignment in
the event of tiles being offset
27 Knock-out point for installed unit
mounting bracket
28 Position of the knurled knobs in the
event of fitted unit mounting bracket
29 Plug for temperature limitation
30 Water plug of the WKMD and WBMD
Stiebel Eltron fittings. In the event of
third party fittings, see „2.10 Water
connection"
31/32 Installation set for surface installation,
see „2.10 Water connection"
33 Cable grommet
12
for the qulified installer

2.2 Important notes

Air in the cold water pipe may de-
stroy the bare wire heating system of
the unit, or cause the safety system to actu-
ate.
If the water feed to the DEL
electronic LCD has been interrupted,
for example due to the risk of freezing,
work on the water mains, etc., the following
procedures must be followed before the
system is taken back into operation:
1. Remove the fuses or disconnect them.
2. Turn any hot water fittings downstream
of the unit fully on until the unit and the
cold water pipe have been bled and are
free of air.
3. Replace the fuses again, or connect them
again.
The DEL electronic LCD unit is
fitted with an air detection device,
which will largely prevent damage
to the heating system:
If air is introduced into the DEL
electronic LCD during operation, the unit
will switch the power off for a few
seconds, and so protect the heating
system.
Note: This function can also be activated
if the fitting is turned on again immedi-
ately after it has been turned off.
All the information provided in these
Instructions for Installation and Use must
be followed carefully. They provide im-
portant details regarding safety, opera-
tion, installation, and maintenance of the
unit.

2.3 Brief description

The DEL electronic LCD electronically
controlled instantaneous water heater is a
pressurised unit for the heating of cold water
in accordance with DIN 1988, with which one
or more water taps can be supplied.
If the preselected output temperature is not
achieved with the tap fully turned on, this
means that more water is flowing through the
unit than the heating elements can heat (out-
put limit 18, 21, 24, or 27 kW). In this event,
the water volume needs to be reduced ac-
cordingly at the hot water outlet.
The bare wire heating system is enclosed with
a pressure-resistant copper jacket. The heating
system is especially well-suited for water with
high limescale risk (for areas of use see Table 3).

2.4 Special fittings

For Stiebel Eltron two-handle pressure fittings
for instantaneous water heaters, see "2.15
Special Accessories".
Installation with conventional commercial
fittings is also possible.
For thermostatic fittings, see Instructions "1.7
Setting recommendations".
2.5 Regulations and provi-
sions
– Installation (water and electrical installation)
and first start-up and maintenance of this
unit may only be carried out by a qualified
installer, in accordance with these Instruc-
tions.
– Trouble-free function and operational reli-
ability and safety can only be guaranteed if
the original accessories and spare parts
intended for the unit are used.
– Regulations of the local energy supply com-
pany.
– Regulations of the water supply company
concerned
– Install the device flush-fitted to the wall in
the lower part (respect the dimension
≥ 110 mm (21)).
Also secure the unit at the bottom (19).
The following details are also to be
respected:
– The unit rating plate
– Technical data.
The specific electrical resistance of
the water must not be less than that
indicated on the rating plate. Where a pub-
lic water supply network is involved, the
lowest electrical resistance of the water is
to be taken into account (see Table 3).
Consult your water supply company for the
specific electrical resistance or electrical
conductivity of the water.
• Water installation
– Material for the cold water pipe:
steel, copper, or plastic pipe systems
– Material for the hot water pipe:
Copper or plastic tube systems *
* The electronic instantaneous water
heaters DEL can reach a temperature
upto max. 60 °C.
In case of failures temperatures can rise
up to 80 °C (max. 1.0 MPa).
The assigned plastic pipe system must
be appropriate for these conditions.
– Operation with preheated water of
more than 60°C is not permitted.
– A safety valve is not required.
– Fittings for open-outlet units are not
permitted.
– Thermostat fittings see „2.15 Special
accessories"
– A safety valve is not required.
• Electrical installation
– Electrical connection only to
permanently installed wiring.
– The unit must be capable of isolation
from the mains, for example by means
of fuses, with an isolating distance of at
least 3 mm to all poles.