Viessmann Vitocal 222-S Installation And Service Instructions For Contractors page 29

Connecting the secondary circuit
Preparing the connections on the DHW side
For connecting the DHW side, observe DIN 1988 and
DIN 4753 (CH: SVGW regulations).
C
B
A D
G
F
E
H
Fig. 25
Expansion vessel, suitable for drinking water
A
Visible discharge pipe outlet point (tundish)
B
Safety valve
C
DHW circulation pump
D
Spring-loaded check valve
E
Automatic thermostatic mixing valve
F
DHW
G
Heat pump terminal area (plan view)
H
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.
Drinking water filter
According to DIN 1988-2, a drinking water filter must
be installed in systems with metal pipework.
Viessmann also recommends the installation of a
drinking water filter when using plastic pipes to
DIN 1988 to prevent contaminants entering the DHW
system.
(cont.)
P
K L M N K
O
K R S K N P
O
Shut-off valve
K
Flow regulating valve
L
Pressure gauge connection
M
Non-return valve/pipe separator
N
Drain valve
O
Cold water
P
Drinking water filter
R
Pressure reducer
S
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.
Installation sequence
29