Technical data
36 | Project planning manual for heat pumps for heating and domestic hot water preparation | 01.2012 www.dimplex.de
3.1.4 Brine-to-water heat pump
Relative pressure drop
The pressure drop of brine is dependent on the temperature and
the mixture. The pressure drop of the brine increases with sink-
ing temperatures and increased concentrates of monoethylene
glycol.
Fig. 3.2: Relative pressure drop of a monoethylene glycol / water mixture
compared with water, dependent upon the concentration at 0 °C
and –5 °C
Table 3.2: Total volume and quantity of antifreeze per 100 m pipe for different
types of PE pipe and frost protection down to –14 °C
3.1.4 Parallel connection of brine-to-water heat pumps
When connecting brine-to-water heat pumps in parallel, it is im-
portant to ensure that no unwanted fluid flows occur in the brine
circuit in individual heat pumps
If only one heat pump is in operation, wrong fluid flows may be
caused in the brine circuit by the heat exchanger of the second
heat pump if a check valve is missing. To help prevent this, a
check valve must be installed in the flow after each brine circuit
pump.
Fig. 3.3: Parallel connection of brine-to-water heat pumps
NOTE
The check valve is not included in the brine accessories package and
must be supplied on site.
A similar unwanted fluid flow can also occur when using a pas-
sive cooling station. Here too, a check valve must be installed
after every brine circulating pump. This must also be supplied on
site.
3.2 Ground heat collector
The energy stored in the ground comes almost exclusively from
the surface of the earth. Precipitation and solar radiation are the
main sources of this energy. Thus, nothing should be built on top
of collectors and the surface should not be sealed. The inflow of
heat from the interior of the earth is less than 0.1 W/m
2
and can,
therefore, be disregarded.
NOTE
The maximum annually extracted energy is 30 to 50 kWh/m² for sandy soil
and 50 to 70 kWh/m
2
for cohesive ground.
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Pipe DIN 8074
(PN 12.5)
[mm]
Volume
per 100 m
[l]
Antifreeze
per 100m
[l]
Maximum
brine flow
rate
[l/h]
25 x 2.3 32.7 8.2 1,100
32 x 2.9 53.1 13.3 1,800
40 x 3.7 83.5 20.9 2,900
50 x 4.6 130.7 32.7 4,700
63 x 5.8 207.5 51,9 7,200
75 x 6.9 294.2 73.6 10,800
90 x 8.2 425.5 106.4 15,500
110 x 10 636 159 23,400
125 x 11.4 820 205 29,500
140 x 12.7 1,031 258 40,000
160 x 12.7 1,344 336 50,000
1
1
D
0
1D
1
0
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