Viessmann Vitocal 350-A Installation And Service Instructions Manual page 32

Preparing for installation
Function description for the system examples
DHW heating
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 ("DHWcirServ")
off during cylinder heating, so this func-
tion is not impaired.
Available booster heaters to reheat the
DHW:
■ External heat source
■ Instantaneous heating water heater
(accessory)
■ Immersion heater EHE (accessory)
The integral load manager in the heat
pump control unit decides which heat
sources to use for DHW heating. Gener-
ally the external heat source has priority
over the electric heaters.
Instantaneous heating water heater (accessory)
An electric instantaneous heating water
heater can be integrated in the heating
water flow as an auxiliary heat source.
Protect the instantaneous heating water
heater via a separate power supply con-
nection.
■ Type AWH-I:
The instantaneous heating water
heater is installed inside the appli-
ance.
■ Type AWH-O:
The instantaneous heating water
heater (with separate control module)
is installed in the heating water flow
inside the building.
32
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 heat-
ing output and actual temperature has
fallen below set temperature at the top
cylinder temperature sensor by more
than "Hyst. booster heater".
Note
The immersion heater EHE (accessory)
in the DHW cylinder and the external
heat exchanger stop as soon as the set
value at the top temperature sensor is
reached, minus a hysteresis of 1 K.
Installation instructions, instanta-
neous heating water heater
The heat pump control unit regulates this
function ("Inst.htg.water heat"). The
instantaneous heating water heater can
be enabled separately for central heating
("Heating with electro") and DHW
heating ("DHW with e heating").
(cont.)