Dhw Heating - Viessmann VITOCAL 300-A Installation And Service Instructions Manual

Preparing for installation
Function description for the system versions
Heating water buffer cylinder operated in parallel
Use of the heating water buffer cylin-
der:
& Bridging power-OFF periods:
At peak times, heat pumps may be
switched off by your local power
supply utility, subject to your electri-
city tariff. During the power-OFF
period, a heating water buffer cylin-
der with its stored heat content pre-
vents the building cooling down.
& Constant volume flow through the
heat pump:
Heating water buffer cylinders pro-
vide hydraulic separation of the
volume flow in the heat pump and
heating circuits. For example, the
flow rate in the heat pump circuit
remains constant, even if the heat-
ing circuit flow rate is reduced by
thermostatic valves.
& Longer heat pump operating times
Systems without heating water buffer cylinder
To safeguard the minimum heating
water volume flow (see specification
page 204), do not install a mixer.

DHW heating

In the delivered condition, DHW heat-
ing through the heat pump takes prior-
ity over the heating circuit.
Instantaneous heating water heater (accessory)
An instantaneous heating water hea-
ter (accessory) can be installed.
36
(cont.)
Because of the increased water
volume of the heat source and the fact
that it may have a separate shut-off
facility, an additional (or larger)
expansion vessel should be provided.
Protect the heat pump in accordance
with EN 12828 [or local regulations].
The control unit switches the DHW cir-
culation pump ("Wtimer DHW Circ.")
off during cylinder heating, so this
function is not impaired.
Installation instructions, instan-
taneous heating water heater