Dhw Heating; Dhw Connection; Function Description Regarding Dhw Heating - Viessmann VITOCAL 300-G Technical Manual

Design information

3.11 DHW heating

DHW connection

Example with Vitocell 100-V, type CVW
Connection to DIN 1988.
B
A
G
C
D
E
A DHW
B DHW circulation line
C DHW circulation pump
D Spring-loaded check valve
E Expansion vessel, suitable for drinking water
F Drain
G Visible blow-off line outlet
H Safety valve
K Shut-off valve
Information on potable water filter
According to DIN 1988-2, a drinking water filter should be installed in
systems with metal pipework. We also recommend the installation of
a drinking water filter when using plastic pipes, as per DIN 1988, to
prevent contaminants entering the DHW system.
Safety valve
Protect the DHW cylinder by means of a safety valve against undue
excess pressure.

Function description regarding DHW heating

Compared to central heating, DHW heating makes fundamentally dif-
ferent demands, as almost identical amounts of heat must be provided
all the year round at the same temperature level.
In the delivered condition, DHW heating by the heat pump takes priority
over the heating circuits.
The heat pump control unit switches the DHW circulation pump off
during cylinder heating to prevent cylinder heating from being
impaired.
The max cylinder storage temperature is limited subject to the heat
pump used and the individual system configuration. With a booster
heater, storage temperatures above this limit are possible.
VITOCAL 300-G
(cont.)
H
K L M NF
F
O
K K F P
L Flow regulating valve
(installation recommended)
M Pressure gauge connector
N Non-return valve
O Cold water
P Drinking water filter
R Pressure reducer to DIN 1988-2 issue Dec,1988
S Non-return valve/pipe separator
Recommendation: Install the safety valve higher than the top edge of
the cylinder. This protects the valve against contamination, scaling and
high temperatures. The DHW cylinder does not then need to be
drained when working on the safety valve.
Available booster heaters to reheat the DHW:
■ External heat source
■ Instantaneous heating water heater (on site)
■ Immersion heater (on site)
The integral load manager in the heat pump control unit decides which
heat sources to use for DHW heating. Generally the external heat
source has priority over the electric heaters.
If one of the following criteria is met, the booster heaters begin cylinder
heating:
■ Cylinder temperature is below 3 °C (frost protection).
■ Heat pump does not provide any heating output and actual temper-
ature has fallen below set temperature at the top cylinder tempera-
ture sensor.
R K S O
VIESMANN
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