Hydraulic Connection, Primary Store System - Viessmann VITOCAL 300-G Technical Manual

Design information
Note
The immersion heater in the DHW cylinder and the external heat
source stop as soon as the set value at the top temperature sensor is
reached, minus a hysteresis of 1 K.
When selecting the DHW cylinder ensure that its indirect coil surface
area is large enough for the purpose.

Hydraulic connection, primary store system

Cylinder with external heat exchanger (primary store system)
DHW
eU
3
eW
eP
KW
W DHW interface (see system examples)
X Solar interface or external heat source (see system examples)
Required equipment
Pos. Description
eP DHW cylinder
eW Cylinder temperature sensor
eE
Cylinder primary pump (DHW side)
eR Plate heat exchanger
eT Flow limiter
eZ Motorised two-way valve, normally closed
eU
DHW circulation pump
VIESMANN
50
(cont.)
eT
M
eZ
eE
X eR
DHW heating should ideally take place during the night after 22:00 h.
This has the following advantages:
■ The heat pump heating output is available for central heating during
the daytime.
■ Night tariffs can be utilised to the full.
■ DHW cylinder heating and simultaneous drawing can be avoided.
When using an external heat exchanger, the system may not always
achieve the required draw-off temperatures because of the system
design.
W
KW Cold water
WW Domestic hot water
VITOCAL 300-G