2. Installation instructions
2.1 Unit structure
1 Output selector
2 Cover
3 Cover lock (cover fixing)
4 Control panel with protective foil
(delivery condition)
5 Hot water screw connection
6 Cold water screw connection(3-way
isolating valve)
7 Terminal block
8 Back wall
9 Fixing screw unit rack (service)
10 Differential pressure switch (control
valve MRC) with flow rate controller
11 Tubular heating element heating system
12 Safety temperature limiter
13 Reset button for safety temperature
limiter (in case of fault)
14 Fixing screw for unit to mounting bra-
cket
15 Unit fixing bottom
16 Electrical supply concealed
17 Electrical supply surface-mounted
18 Dimension for installation "Wall flush-
mounted"
19 Mounting bracket
20 Unit fixing holes
21 Fixing bolts with nut for rear wall
alignment in case of tile set-off
22 Strainer
23 Water plug for surface mounting with
WKMD or WBMD fitting.
Connection with foreign fittings see
"2.12 Special fittings"
24-25 Mounting set surface installation (see
"2.12 Special fittings")
25 a Copper pipe 12 mm (supplied by
customer)
26 Cable pipe
27 Fixing screw unit bottom
for the qualified installer
2.2 Brief description
The hydraulically controlled instantaneous
water heater DHF ... C compact control is a
pressurized unit for heating cold water to
DIN 1988, which can supply one or more
water taps.
The flow rate control of the control valve
compensates for pressure variations and thus
ensures a largely constant temperature. The
control valve MRC limits the flow rate and
hence guarantees a sufficient temperature
increase in the drinking water, even in winter.
The tubular heating element heating system
in pressurized copper container can be used
in water with a low lime content (Area of
use see Table 3).
2.3 Fittings
# Fittings for open units are not permitted!
# In case of low water pressure hand-held
showers with low pressure loss must be
fitted see "2.12 Special fittings".
# Stiebel Eltron twin-handle fittings for
instantaneous water heater see "2.12
Special fittings".
# One-hand mixer and thermostatic fittings
must be suitable for hydraulically
controlled instantaneous water heaters.
# Practical hints:
So that the switch-on quantities (see Ta-
ble 3) of stage ! and stage !! are safely
reached, the pressure loses of the instan-
taneous water heater, fitting, hand-held
shower, shower hose and the pipe net-
work must be taken into account upon
installation.
Typical pressure loss values for a shower
water quantity of approx. 10 l/min:
– one-hand mixer . . . . . 0.04 - 0.08 MPa
– thermostatic fittings . . 0.03 - 0.05 MPa
– hand-held shower . . . . 0.03 - 0.15 MPa
2.4 Provisions and
regulations
" Installation (water and electrical
installation), as well as the first start-up and
maintenance of this unit, may only be
carried out by a qualified installer in
accordance with these instructions.
" Faultless operation and operational safety
are only guaranteed if the original accesso-
ries and spare parts intended for the unit
are used.
" DIN VDE 0100.
" Regulations of the local energy supply
company.
" DIN 1988 / DIN 4109.
" Regulations of the relevant water supply
company.
" Install the unit flush with the wall at the
lower end (18, observe dimension
! 110 mm).
The following should also be ob-
served:
" The unit rating plate.
" Technical data.
" Water installation:
– cold water pipe material:
Steel, copper
Plastic piping systems:
For the cold water unit connection a
metal pipe of approx. 1 m long must be
installed.
– hot water pipe material:
Copper
Plastic piping systems:
The DHF ... C is not suitable for installa-
tion with plastic piping systems for the
hot water pipe!
" A safety valve is not necessary.
" Operation with pre-heated water is not
permitted!
" Thermostatic tap fittings - see "1.5 Adjust-
ment recommendation".
" Electrical installation:
" Electrical connection only to permanently-
installed cables.
" It must be possible to isolate the unit from
the main supply on all poles with an isolat-
ing distance of at least 3 mm, for example
using fuses.
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