Technical data

96 | Project planning manual for heat pumps for heating and domestic hot water preparation | 01.2012 www.dimplex.de
8.3.3 Integration of the heat pump in the heating system
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 vol-
ume flows in the consumer circuit, the main circuit (M13) heat cir-
culating pump can also be used to maintain the flow through the
heat pump and the heating system (see Fig. 8.39 on page 119).
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 com-
pensated 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 dur-
ing operation (depending on usage) so that the most unfa-
vourable 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 listed in Chapt. 8.3.2 on page 95 for the current
heat source temperature. The temperature spread should
be measured as close as possible to the heat pump.
NOTE
If the overflow valve is closed too far, the minimum heating water flow
rate through the heat pump is not guaranteed.
If the overflow valve is opened too far, individual heating circuits may no
longer have a sufficient flow.
8.3.4 Differential pressureless manifold
The minimum heating water flow rate is maintained by the heat
pump under all operating statuses through the hydraulic isolation
of the generator circuit from the consumer circuit (see Fig. 8.40
on page 119).
The installation of a differential pressureless manifold is recom-
mended for:
 Heating systems with radiators
 Heating systems with more than one heating circuit
 Unknown pressure drops in the consumer circuit (e.g. in ex-
isting buildings)
The main circuit (M13) heat circulating pump ensures the mini-
mum heating water flow rate of the heat pump for all operating
states without the need for manual settings.
Different volume flows in the heat generator and consumer cir-
cuits are balanced via the differential pressureless manifold. The
pipe cross section of the differential pressureless manifold
should have the same diameter as the heating system flow and
return.
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
of to
-5° C 0 °C 10K
1 °C 5 °C 11K
6 °C 9 °C 12K
10 °C 14 °C 13K
15 °C 20 °C 14K
21 °C 25 °C 15K
Heat source
temperature
Max. temperature spread
between heating flow and return
of to
7° C 12 °C 10K
13 °C 18 °C 11K
19 °C 25 °C 12K