ᐅ Experiences with ground-source heat pumps using a borehole and water as the heat transfer medium?

Hello everyone,

we are about to build a house (key details below). So far, a ground-to-air heat pump is planned. However, the more I read about it, the more doubtful I become whether it is the right choice: numerous reports about air-to-water heat pumps breaking down in freezing temperatures (when you actually need them), malfunctioning defrost cycles of the outdoor unit, noise emissions from the outdoor unit, and a maximum lifespan of 15-20 years.

Therefore, I am considering a ground-to-water heat pump as an alternative. Our plot is rather small, so drilling is the only option. I am aware of the disadvantages like initial and drilling costs and the requirement for a building permit/planning permission, and I accept these. In the end, I need a system that works reliably without breaking down in winter conditions (otherwise, the whole family has to wait for a week or more in a cold house until repairs are done), that operates relatively quietly, and possibly lasts a long time. A passive cooling function in summer is also attractive.

These are my considerations, now the questions:
1. Does anyone have experience with ground-to-water heat pumps with probes? Especially whether they actually work without problems?
2. The compressor would then be located in the basement along with the pump – how quiet is it?
3. Where is the drilling usually done for the probes – directly under the house or beside it? Regarding the timing – should this be completed before construction starts or can it be done in parallel next to it?
4. Approximately how long does the approval process take (possibly including water law permits)?

Key details of the house:

• Semi-detached house, solid construction, not a KfW-standard house (EnEV 2016)
• Two full floors plus basement, ground floor + upper floor 68 + 68 m² (732 + 732 sq ft), plus about 30 m² (320 sq ft) of heated basement area
• Underfloor heating, controlled ventilation system (mechanical ventilation) with heat recovery and enthalpy heat exchanger
• No photovoltaic system planned primarily

Thank you very much!
Best regards
Nils