Technical data
www.dimplex.de 01.2012 | Project planning manual for heat pumps for heating and domestic hot water preparation | 45
Brine-to-water heat pump 3.5.1
3.5 Heat source water with intermediate heat exchanger
3.5.1 Use of water heat source in the event of contamination
To enable indirect use of the heat source water, brine-to-water
heat pumps can be operated via an intermediate circuit with ad-
ditional stainless steel heat exchangers. To this end, an addi-
tional heat exchanger is installed in the heat source circuit of the
heat pump and the intermediate circuit is filled with monoethyl-
ene glycol.
The external stainless steel heat exchanger makes it possible to
use the heat source ground water, even in areas with relatively
high water soiling levels. In areas with water temperatures below
13 °C throughout the year, no water analysis is required with re-
gard to corrosion.
ATTENTION!
If the limit values for iron (Fe to 0.2 mg/l) or manganese (Mn to 0.1 mg/l)
are exceeded, there is a risk of sedimentation forming in the heat source
system. This also applies when using stainless steel heat exchangers.
NOTE
An online planner, which can be used to calculate the seasonal perform-
ance factor (including intermediate heat exchangers), is available at
www.dimplex.de/betriebskostenrechner.
A number of different packages are available, consisting of heat
pump, heat exchanger, matching brine accessories and a safety
thermostat to help protect the heat pump from freezing. In this
case, the heat pump output values are listed differently under op-
erating point B7/W35. This corresponds to a brine inlet tempera-
ture of 7 °C with an assumed water temperature of 10 °C and a
grade or spread via the heat exchanger of 3 K.
Table 3.6: Heat pump packages with intermediate heat exchanger
Fig. 3.14: Heat pump with intermediate heat exchanger
The flow rate switch in the primary circuit (FS) prevents the heat
pump from switching on if the volume flow of the cooling water or
ground water pump is not present.
The intermediate heat exchanger circuit must be filled with anti-
freeze for brine-to-water heat pumps (at least -14 °C).
The brine circuit should be equipped with a circulating pump and
safety valves in the same way as for standard ground heat col-
lectors and borehole heat exchangers. The circulating pump
should be dimensioned in a way which ensures that the interme-
diate heat exchanger does not freeze.
If a brine-to-water heat pump is used, the temperatures in the
secondary circuit can fall below 0°C. The intermediate heat ex-
changer must be protected using an additional frost protection
thermostat (T). This must be installed at the water outlet of the
primary circuit in order to ensure that the heat exchanger does
not freeze. When the thermostat is switched off, the heat pump is
blocked via digital input ID3 of the heat pump manager. The ther-
mostat should also be passed on as an error message to the
building management system where prevent the heat pump from
surging. The switch-off point of the thermostat (e.g. 4°C) de-
pends on the system configuration, the measurement tolerances
and the hystereses.
The maximum permissible flow temperature on the heat source
side of a brine-to-water heat pump is 25 °C. There are a number
of different ways to prevent the heat pump from switching off due
to excessively high brine inlet temperatures.
ATTENTION!
The terminal assignment of the heat pump manager specified in the
relevant installation instructions must be complied with!
NOTE
For the installation of a brine-to-water heat pump with intermediate heat
exchanger, the water flow in the primary cycle must be at least 10% above
the flow rate of the secondary circuit.
Order reference Heat pump Heat exchanger
Brine circuit
accessories
Heat output
with B7/W35
COP with B7/W35
WSI 36TE SI 30TE WTE 30 SZB 300 36 kW 4.9
WSI 44TE SI 37TE WTE 37 SZB 400 44 kW 5.2
WSI 55TE SI 50TE WTE 50 SZB 500 55 kW 4.9
WSI 85TE SI 75TE WTE 75 SZB 750 85 kW 4.9
WSI 110TE SI 100TE WTE 100 SZB 1000 113 kW 5.1
WSI 150TE SI 130TE WTE 130 SZB 1300 145 kW 4.9
WSIH 26TE SIH 20TE WTE 20 SZB 250 26 kW 5.0
WSIH 44TE SIH 40TE WTE 40 SZB 400 44 kW 4.9
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