Installation manual
176
8.3.2
8.3.2 Temperature spread in relation to the heat source temperature
The heat output of the heat pump depends on the heat source
temperature. This is especially the case, when the outside air is
used as the heat source.
The maximum temperature spread in relation to the heat source
temperature can be found in the following tables.
Air-to-water heat pump
Table 8.1: Outside air heat source (temperature can be read from the heat
pump manager!), operation with 1 compressor
Brine-to-water heat pump
Table 8.2: Heat source: ground, operation with 1 compressor
Water-to-water heat pump
Table 8.3: Heat source: Ground water, operation with 1 compressor
8.3.3 Overflow valve
In the case of systems with only one heating circuit and even
volume flows in the consumer circuit, the main circuit (M13) heat
circulating pump (see Fig. 8.26 on p. 191) can also be used to
maintain the flow through the heat pump and the heating system.
If room temperature controllers are used, the radiator valves and
thermostat valves could cause the volume flows in the consumer
circuit to fluctuate. These volume flow fluctuations must be
compensated for by an overflow valve installed in the heating
bypass downstream from the unregulated heating pump main
circuit (M13).
If there is an increasing drop in pressure in the consumer circuit
(for example because valves are in the process of being closed)
a partial volume flow is directed through the heating bypass, thus
ensuring a minimum heating water flow rate through the heat
pump.
NOTE
Electronically regulated circulating pumps which reduce the volume flow
with increasing drops in pressure should not be used in combination with
an overflow valve.
Overflow valve adjustment
Close all of the heating circuits that may also be closed
during operation (depending on the type of heat pump
usage) so that the most unfavourable operating state - with
respect to the water flow - is achieved. This normally means
the heating circuits of the rooms on the south and west sides
of the building. At least one heating circuit must remain open
(e.g. bathroom).
The overflow valve should be opened far enough to produce
the maximum temperature spread between the heating flow
and return flow listed in Chap. 8.3.2 on p. 176 for the current
heat source temperature. The temperature spread should
be measured as close as possible to the heat pump.
NOTE
If an overflow valve is closed too tightly, the minimum heating water flow
rate through the heat pump can not be guaranteed.
Conversely, if an overflow valve is open too wide, individual heating
circuits might not have a sufficient flow rate.
8.3.4 Differential pressureless manifold
The minimum heating water throughput is maintained by the heat
pump under all operating statuses (see Fig. 8.27 on p. 191)
through the hydraulic isolation of the generator circuit from the
consumer circuit.
Installation of a manifold without differential pressure is
recommended for:
Heating systems with radiators
Heating systems with more than one heating circuit
Unknown pressure drops in the consumer circuit (e.g. in
existing buildings)
The main circuit (M13) heat circulating pump ensures the
minimum heating water flow rate of the heat pump for all
operating statuses without the need for manual settings.
Different volume flows in the heat generator and consumer
circuits are balanced via the manifold without differential
pressure. The pipe cross section of the manifold without
differential pressure should have the same diameter as the
heating system flow and return flow.
NOTE
The maximum flow temperature of the heat pump in the heating circuits
will not be reached if the volume flow in the consumer circuit is higher
than the the volume flow in the generator circuit.
Heat source
temperature
Max. temperature spread between
heating flow and return flow
From To
-20 °C -15 °C 4 K
-14 °C -10 °C 5 K
-9 °C -5 °C 6 K
-4 °C 0° C 7 K
1°C 5 °C 8 K
6°C 10 °C 9 K
11 °C 15 °C 10 K
16 °C 20 °C 11 K
21 °C 25 °C 12 K
26 °C 30 °C 13 K
31 °C 35 °C 14 K
Heat source
temperature
Max. temperature spread between
heating flow and return flow
From To
-5 °C 0 °C 10 K
1 °C 5 °C 11 K
6 °C 9 °C 12 K
10 °C 14 °C 13 K
15 °C 20 °C 14 K
21 °C 25 °C 15 K
Heat source
temperature
Max. temperature spread between
heating flow and return flow
From To
7 °C 12 °C 10 K
13 °C 18 °C 11 K
19 °C 25 °C 12 K