Technical data

48 | Project planning manual for heat pumps for heating and domestic hot water preparation | 01.2012 www.dimplex.de
4 Water-to-water heat pump
4 Water-to-water heat pump
4.1 Ground water as a heat source
Temperature range of the ground water 7 to 12 ° C
Operating range of the water-to-water heat pump 7 to 25 °C
Availability
 Year round
Types of operation
 Monovalent
 Mono energy
 Bivalent (alternative, parallel)
 Bivalent-renewable
Development costs
 Approval process (local water authority)
 Extraction wells / absorption well with air-tight
seal on the wellheads
 Water quality (water analysis)
 Pipework
 Well pump
 Excavation/construction work
Maintenance information
To guarantee safe operation of the heat pump, maintenance
work must be carried out on the heat pump at regular intervals.
The following work can be carried out with no special training:
 Cleaning inside the heat pump
 Cleaning the filter in the primary circuit
The heat pump must also be checked for leaks and the function
of the refrigerant circuit checked at regular intervals.
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.
Work on components carrying refrigerant may only be carried out by per-
sonnel with relevant training.
Tapping the ground water heat source
Starting at a well depth of between 8 and 10m, the ground water
heat source is suitable for monovalent heat pump operation, as it
is only susceptible to minor temperature fluctuations throughout
the year (7-12°C). Approval is required from the appropriate
water authorities for heat extraction from ground water. Permis-
sion is generally given outside of water protection zones. How-
ever, permission is dependent on certain conditions, e.g. a spec-
ified maximum amount of water that may be withdrawn, or a
water analysis. The amount of water that may be withdrawn de-
pends on the heat output. Table 4.1 on page 49 lists the neces-
sary withdrawal quantities for the operating point W10/W35.
A well system with extraction and absorption wells should be de-
signed and constructed by a drilling company accredited with the
seal of approval from the International Heat Pump Association or
authorised according to DVGW W120. In Germany, the informa-
tion in the Association of German Engineers' (VDI) publication
VDI 4640 Parts 1 and 2 should be taken into consideration.
NOTE
Two wells are required for the withdrawal of ground water, an “extraction
well” and an “absorption well”. For economic reasons, for heat pumps
with a heat output of up to 30 kW, ground water should not be pumped
from depths greater than 15 m.