6 × 60 m am Bartholomäberg

For a holiday home on Bartholomäberg in Montafon, six separatus geothermal heat probes with a depth of 60 metres were constructed. The total probe length is 360 metres. An aquifer floor required an adapted drilling sequence. separatus took over the thermal simulation and design / system sizing, Plankel the drilling and the probe installation. In the 22.07.2026 project report, Geser Erdwärme was intended for the subsequent hydraulic connection.

Why planned 53 metres per probe became 60 metres

The holiday home is located at approximately 734 metres above sea level. In the first planning, six borehole heat exchangers with 53 metres depth were roughly calculated. In the detailed planning, separatus checked the project-specific boundary conditions with a thermal simulation.

The initially flat-rate specific withdrawal benefit for this location was rather optimistic. Taking into account climate and local geology, the planning team recommended longer probes. Six probes à 60 metres were executed.

For the client, this planning means a concrete adaptation of the geothermal system to the location. The probe length is based on the project-specific design / system sizing.

What the simulation about brine temperatures says

The thermal simulations described in the separatus project report suggest higher brine temperatures with separatus than with a conventional double U-tube BHE for this project. The reason given in the report is the flow conditions: In the case of the project-specific volume flows, the double U variant would have been predominantly laminar flow expected; For separatus, the report describes more favorable hydraulic conditions under the same boundary conditions.

This statement refers to the simulated comparison for the holiday home. Specific temperature differences or measured operating results are not mentioned in the project report.

How drilling was adapted to groundwater

Plankel first introduced a tubing with 160 millimeter diameter in the flush drilling process. Subsequently, the pipeline was converted to the down-the-hole (DTH) hammer drilling. With 132 millimeter drilling diameter, the drilling was continued up to 60 metres each.

Plankel installed the separatus geothermal heat probes and backfilled the wells with Fischer GeoSolid. The documented design thus combines two drilling methods for the different geological areas.

Who takes over which project phase

thermal simulation and design / system sizing · Company involved: separatus
Drilling and probe installation · Company involved: Plankel
Hydraulic connection · Company involved: Geser Erdwärme

After probe installation, Geser Erdwärme was intended for connection to the distribution system and integration into the overall system, according to the 22.07.2026 project report. The project report describes this step as an upcoming performance; a completed connection or commissioning is not documented therein.

Overview of project data

Object · Documented information: Holiday home
Location · Documented information: Bartholomäberg im Montafon, Vorarlberg, Austria
Sea level · Documented indication: approximately 734 metres
First rough planning · Documented information: 6 probes à 53 metres
Designed probe system · Documented information: separatus geothermal heat probes
Number and depth · Documented indication: 6 probes à 60 metres
Total probe length · Documented information: 360 metres
Tube diameter · Documented indication: 160 mm
Drilling diameter at down-the-hole (DTH) hammer drilling · Documented information: 132 mm
Geological specificity · Documented information: Groundwater floor
borehole grouting · Documented information: Fischer GeoSolid

The reference shows how simulation, drilling technology and hydraulic connection are coordinated within the separatus partner network. For a geothermal project in Vorarlberg, the network supports everything from simulation to drilling to hydraulic connection.