Viessmann VITOCAL 151-A Installation And Service Instructions Manual page 36

Installation sequence
Connecting the secondary circuit
Preparing connections on the heating water side
Equip the heating system on site with an expansion
vessel in the heating return.
The expansion vessel must be approved to EN 13831.
Preparing the connections on the DHW side
For connecting the DHW side, observe EN 806,
DIN 1988, DIN 4753, TrinkwV Drinking Water Ordi-
nance [Germany] and DVGW (CH: SVGW regula-
tions). Observe other country-specific standards as
applicable.
C
B
E
F
D
A
Fig. 27
Expansion vessel, suitable for drinking water
A
Visible discharge pipe outlet point
B
Safety valve
C
Automatic thermostatic mixing valve
D
DHW
E
Shut-off valve
F
Flow regulating valve
G
Safety valve
The DHW cylinder must have a safety valve to protect
against unduly high pressure.
Recommendation: Install safety valve above top edge
of cylinder. This means the DHW cylinder will not need
to be drained when working on the safety valve.
CH: According to W3 "Principles for creating potable
water installations", safety valves must be drained
directly via a visible unrestricted drain or via a short
outlet line to the drain network.
36
L
G H K F F
O O
Note
With underfloor heating circuits, install a temperature
■
limiter to restrict the maximum temperature of under-
floor heating systems.
■ Ensure the minimum flow rate, e.g. by means of an
overflow valve: See "Specification".
M N F K L
Pressure gauge connection
H
Non-return valve/pipe separator
K
Cold water
L
Drinking water filter
M
Pressure reducer to DIN 1988-200:2012-05
N
Drain valve
O
Drinking water filter
According to DIN 1988-2, a drinking water filter must
be installed in systems with metal pipework. Viess-
mann also recommends the installation of a drinking
water filter when using plastic pipes to DIN 1988 to
prevent contaminants entering the DHW system.
Automatic thermostatic mixing valve
With appliances that heat DHW to temperatures above
60 °C, an automatic thermostatic mixing valve must be
installed in the DHW line as protection against scald-
ing.