ᐅ Experiences with ground-source heat pumps using a borehole and water as the heat transfer medium?
Created on: 1 Feb 2023 23:05
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NilsHolgersson
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:
Thank you very much!
Best regards
Nils
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
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WilderSueden4 Feb 2023 09:33Stephan— schrieb:
On the topic, do you all have one of those ugly pressure relief tanks in case you ever need one? Or how was this handled in your homes? Our heating technician says it shouldn’t be discharged into the wastewater system.We don’t have something like that, but we do have a hose that runs once around the equipment room to the utility sink 😉 I need to check tomorrow if I can figure out whether it’s coming from the heat pump
Stephan— schrieb:
On the topic, do you all also have an unsightly pressure relief tank in case you ever need one?Yes, but it is hidden behind the heat pump. There was something in it at the very beginning, but since then it has been dry.N
NilsHolgersson6 Feb 2023 09:14Thank you all very much again!
I have now directly contacted our heating installer (a subcontractor of the construction company): he can also install a ground-source heat pump. It would be a unit from Viessmann. Are Viessmann units good as ground-source heat pumps?
For air-source heat pumps, he also recommended one from Viessmann, but there are many reports of problems with them, so we have potentially decided on Ochsner (reluctantly from the installer's side).
Basically: Are the differences in terms of maintenance needs, error messages, etc., less significant for ground-source heat pumps compared to air-source heat pumps with an outdoor unit?
Or would it be better to plan for a brand other than Viessmann right from the start in this case?
I have now directly contacted our heating installer (a subcontractor of the construction company): he can also install a ground-source heat pump. It would be a unit from Viessmann. Are Viessmann units good as ground-source heat pumps?
For air-source heat pumps, he also recommended one from Viessmann, but there are many reports of problems with them, so we have potentially decided on Ochsner (reluctantly from the installer's side).
Basically: Are the differences in terms of maintenance needs, error messages, etc., less significant for ground-source heat pumps compared to air-source heat pumps with an outdoor unit?
Or would it be better to plan for a brand other than Viessmann right from the start in this case?
As Fuchur says: the most important thing is that it modulates and is *properly sized*. This is crucial because even a modulating heat pump has lower limits – if it is oversized, it will still not always operate optimally.
You should also consider the cooling function right from the start: with some manufacturers, upgrading later is not possible – I’m not sure if the same applies to Viessmann.
It is also worth considering whether to choose a mechanical ventilation with heat recovery device from Viessmann as well, so that the control can be integrated via the heat pump or heat pump interface.
You should also consider the cooling function right from the start: with some manufacturers, upgrading later is not possible – I’m not sure if the same applies to Viessmann.
It is also worth considering whether to choose a mechanical ventilation with heat recovery device from Viessmann as well, so that the control can be integrated via the heat pump or heat pump interface.
NilsHolgersson schrieb:
Thank you all again!
I have now contacted our heating installer (a subcontractor of the construction company) directly: he can also handle the installation of a brine-to-water heat pump. It would be a unit from Viessmann. Are Viessmann brine-to-water heat pumps good?
For air-to-water heat pumps, he also recommended one from Viessmann, but there are many reports of problems, which is why we might potentially go with Ochsner (reluctantly from the installer’s side).
In general: are the differences regarding brine-to-water heat pumps (maintenance, error messages, etc.) less significant than with air-to-water heat pumps that have an outdoor unit?
Or would it be better to plan for a brand other than Viessmann from the start? We still have the "old" Vitocal 333-G, which is on/off and does not have modulation (the new version can do that). But it does what it should without complaints and quietly. In operation since 2018, with an annual performance factor of 5.3 at roughly 1700 kWh/year consumption (130m2 (1400 sq ft) energy-saving standard 2016, built in 2018). Also paired with the matching ventilation system Vitovent 300-F.
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