Water-to-water heat pump (groundwater)

The water-to-water heat pump uses groundwater as a heat source. It is highly efficient, but requires wells and a water rights permit.

With a water-to-water heat pump, groundwater is pumped up via an extraction well. The heat pump extracts heat from it, after which the cooled water is returned to the ground via an injection well or soakaway. The groundwater is therefore not consumed, only slightly cooled.

Advantages

• According to klimaaktiv, groundwater has a relatively high and constant temperature. It is therefore a particularly good heat source and enables high efficiency.
• The klimaaktiv guide recommends a COP W10/W35 of over 5.5 for groundwater heat pumps, the highest guide value of all heat sources.
• In summer, gentle cooling is possible.

Disadvantages

• Groundwater is not available everywhere in suitable quantities and depths.
• During planning, water level fluctuations and water quality must be taken into account.
• According to klimaaktiv, groundwater heat pumps are relatively complex to install and operate for the typical energy requirements of a detached home. They become interesting if cooling in summer is also important.

Permit

The use of groundwater is regulated by the authorities. The federal state of Upper Austria states that the installation and operation of groundwater heat pumps always require a permit under the Wasserrechtsgesetz (Water Rights Act). The protection of the drinking water supply takes priority. Allow time for the process and enquire early with the Bezirkshauptmannschaft (district authority), see approval.

You can find a comparison with other sources in air or geothermal energy.

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