Viessmann Vitocal 300-G BW, Installation And Service Instructions Manual

Page: 14 / 216

14
Note
The sample applications are recommendations and must be checked for complete-
ness and functionality on site. Please observe the applicable regulations and direc-
tives for design, installation and operation.
Heating circuit
Heat pumps require a minimum
throughput of heating water (see spec-
ification on page 203). Ensure that the
values specified in the relevant data-
sheet are maintained .
Accurately calculated radiator heating
systems generally have a small system
water content. With systems like these,
use a heating water buffer cylinder with
an appropriate capacity to prevent the
heat pump from being switched on and
off at frequent intervals.
Heat pumps can be shut off by the power
supply utility at peak load periods
depending on the power tariff. For this
reason install a heating water buffer cyl-
inder in rapidly cooling buildings.
The system versions with heating water
buffer cylinder do not use a secondary
pump but a separate circulation pump as
heating circuit pump. We recommend
the use of a heating circuit pump with a
slower flow rate than the secondary
pump.
Systems with large water volumes, e.g.
underfloor heating systems, can operate
without a heating water buffer cylinder.
In these heating systems install an over-
flow valve at the underfloor heating sys-
tem heating circuit distributor that is fur-
thest away from the heat pump. This
ensures that the minimum circulation
volume is provided, even in closed heat-
ing circuits.
In conjunction with an underfloor heating
system, install a temperature limiter
(accessory, order no. 7151 728 or
7151 729) (connection, see page 76).
Heating water buffer cylinder operated in parallel
Heating water buffer cylinders provide a
hydraulic separation of the 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 ther-
mostatic valves. Use of the heating water buffer cylin-
der:
■ Bridging power-OFF periods
■ Constant flow rate through the heat
pump
■ Longer heat pump operating times
Preparing for installation
Function description in connection with the system versions
5368 522 UAE