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

Function description for the system versions

Heating circuit

Minimum volume flow
Heat pumps require a minimum heat-
ing water volume flow (see specifica-
tion on page 204). Maintain the values
shown in the technical guide at all
times. To ensure the minimum
volume flow, install an overflow valve.
Systems with small water volumes
For systems with small water volumes
(for example, heating systems with
radiators), use a heating water buffer
cylinder to prevent excessive heat
pump cycling (starting/stopping).
Systems with large water volumes
Systems with large water volumes (for
example, underfloor heating systems)
can operate without a heating water
buffer cylinder. In these heating sys-
tems install an overflow valve at the
heating circuit distributor of the under-
floor heating system that is furthest
away from the heat pump. This safe-
guards the minimum volume flow,
even in closed heating circuits.
Preparing for installation
(cont.)
In conjunction with an underfloor
heating system, install a temperature
limiter (accessory, order no. 7151 728
or 7151 729) (for connection, see
page 84).
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