Technical data

34 | Project planning manual for heat pumps for heating and domestic hot water preparation | 01.2012 www.dimplex.de
3 Brine-to-water heat pump
3 Brine-to-water heat pump
3.1 Ground as a heat source
Temperature range of the ground surface
at approx. 1 m depth +3...+17°C
Temperature range in deep layers
(approx. 15 m) +8...+12°C
Operating range of the brine-to-water heat pump -5 to +25°C
NOTE
If commissioning is carried out by the after-sales service and the anti-
freeze contains 30% monoethylene glycol, the lower operating limit of the
high-efficiency brine-to-water heat pumps can be expanded to -10 °C.
Types of operation
 Monovalent
 Mono energy
 Bivalent (alternative, parallel)
 Bivalent-renewable
NOTE
Notes on the indirect use of the ground water as a heat source and/or of
waste heat from cooling water with the combination of brine-to-water heat
pumps and intermediate heat exchangers can be found in Chapt. 3.5 on
page 45.
3.1.1 Dimensioning information - ground heat source
The ground heat exchanger, which serves as a heat source for
the brine-to-water heat pump, should be designed according to
the refrigerating capacity of the heat pump. This can be calcu-
lated using the heat output minus the electric power consumption
of the heat pump as calculated in the design point.
NOTE
A heat pump with a higher COP has, at comparable heat output, less elec-
trical power consumption and, therefore, higher refrigerating capacity.
When replacing an older heat pump with a newer model, check
the capacity of the ground heat exchanger and, if necessary,
modify it to suit the new refrigeration capacity.
Under ground, heat is conveyed almost solely by thermal con-
duction, whereby the thermal conductivity increases with in-
creasing water content. Like the thermal conductivity, the heat
storage capacity is also largely determined by the water content
of the ground. If the water in the ground is frozen, the amount of
energy which can be extracted increases considerably because
the latent heat of water at approx. 0.09 kWh/kg is very high.
Therefore, optimal utilisation of the ground as a heat source is
not impaired if the buried pipe coils freeze.
Dimensioning of the brine circulating pump
The brine volume flow rate depends on the output of the heat
pump, and is conveyed by the brine circulating pump. The brine
flow rate specified in the "Device information" manual results in a
heat source temperature spread of approx. 3K.
In addition to the volume flow rate, the pressure drops in the
brine circulation system and the technical data of the pump man-
ufacturer should also be taken into consideration. The pressure
drops in pipes connected in series, installed components and the
heat exchangers should be added.
NOTE
The pressure drop of an antifreeze/water mixture (25 %) is 1.5 to 1.7 times
higher (see Fig. 3.2 on page 36) than that of pure water, whereas the ca-
pacity of many circulating pumps drops by approx. 10 %.
NOTE
A detailed outline of ground heat collectors is possible for all regions in
Germany with the operating cost calculator at www.dimplex.de/betrieb-
skostenrechner.
Maintenance information
To guarantee safe operation of the heat pump, maintenance
work must be carried out on the pump at regular intervals. The
following work can be carried out with no special training:
 Cleaning inside the heat pump
NOTE
Further information of country-specific standards relating to leakage
tightness tests on heat pumps is available at www.dimplex.de/dichtheits-
pruefung.
NOTE
Further information on heat pump maintenance is available in the heat
pump installation instructions.
ATTENTION!
Work on components carrying refrigerant may only be carried out by
personnel with relevant training.