Our four-unit building (390 sqm (4,198 sq ft)) is still looking for the right heating system to meet the city’s KfW55 requirement.
Therefore, a question about the possibility of a groundwater heat pump:
We already know that this system would likely achieve high efficiency (annual performance factor >4), so the additional cost compared to gas plus solar thermal or an air-to-water heat pump for our heating demand would likely be recovered relatively quickly (about 10–16 years). But what are the potential disadvantages that we might not yet be aware of? Is a groundwater heat pump more maintenance-intensive?
(Regarding the conditions, if anyone is interested:
According to the soil expert, a groundwater heat pump is probably feasible here (one was successfully installed 300 m (984 ft) away). To verify whether this will work, a borehole would first have to be drilled to 20 m (66 ft) to definitively assess the composition of the soil and water. This borehole would then serve as the infiltration well.
Cost for the first borehole including everything: €3500, total cost for borehole and pump in the end: €16,500. We would be investing this first amount at risk, with the possibility that we cannot install the system and would “only” have an expensive domestic water well. Hence the inquiry here.)
Therefore, a question about the possibility of a groundwater heat pump:
We already know that this system would likely achieve high efficiency (annual performance factor >4), so the additional cost compared to gas plus solar thermal or an air-to-water heat pump for our heating demand would likely be recovered relatively quickly (about 10–16 years). But what are the potential disadvantages that we might not yet be aware of? Is a groundwater heat pump more maintenance-intensive?
(Regarding the conditions, if anyone is interested:
According to the soil expert, a groundwater heat pump is probably feasible here (one was successfully installed 300 m (984 ft) away). To verify whether this will work, a borehole would first have to be drilled to 20 m (66 ft) to definitively assess the composition of the soil and water. This borehole would then serve as the infiltration well.
Cost for the first borehole including everything: €3500, total cost for borehole and pump in the end: €16,500. We would be investing this first amount at risk, with the possibility that we cannot install the system and would “only” have an expensive domestic water well. Hence the inquiry here.)
T
toxicmolotof26 May 2018 14:43Lückenfüller schrieb:
It is a groundwater protection zone 3, but the local environmental authority has explicitly mentioned the possibility of such a heat pump. However, a brine heat pump is therefore not an option.When I hear something like this again. With the right sealing material and the proper brine, it should also be possible in a protection zone class 3. At least that’s how it works here.
After all, it’s not class 1 or 2, but only 3.
It’s similar to the gravel case. For private use, no recycled crushed concrete (RCC) is allowed in protection zone class 3. But on the street next door, the city does exactly that. And for a donation of 200 euros to the city treasury, private individuals are allowed to do it again.
Alex85 schrieb:
Away from water protection zones, a probe—for example—can be prohibited if it would connect two groundwater layers.
Laypersons don’t need to talk about injection material and casing if the authority’s approval is not granted.Or if there is gypsum in the soil. That causes interesting distortions when water comes into contact with it.
T
toxicmolotof27 May 2018 12:00Alex85 schrieb:
Away from water protection areas, probes can be prohibited, for example, if two groundwater layers would be connected.
Laypeople don’t need to babble about grouting material and casing if the authority’s approval isn’t granted.However, as you yourself have noticed, this has nothing at all to do with the water protection area. And you don’t necessarily have to drill directly into both layers if conditions allow. Otherwise, a water-to-water heat pump would probably only be permitted down to the first layer.
The same applies to gypsum. In that case, a water-to-water heat pump would probably also be impractical.
L
Lückenfüller27 May 2018 13:37Thank you very much in advance for your comments!
Water Protection Area / Authority:
We are located in a WSG 3a area. The (local) environmental authority has made it very clear to me in several discussions that they will not approve a brine heat pump (which other builders who tried have also confirmed). At the same time, they explicitly mentioned the possibility of using a groundwater heat pump (verbally, not in writing). Our planner explained that this ban is probably not legally enforceable anymore, as refrigerants approved for WSG 3a zones are now available. But the question is whether we really want to pursue this legally?
Soils:
We are very close to the Rhine, so the soils consist mainly of sand and gravel. It is still uncertain whether silty extensions from a nearby mountain range will be found at around 20 meters (65 feet) depth. And of course, there is the usual mineral content and flow velocity, which matched the conditions in neighboring projects.
Water Protection Area / Authority:
We are located in a WSG 3a area. The (local) environmental authority has made it very clear to me in several discussions that they will not approve a brine heat pump (which other builders who tried have also confirmed). At the same time, they explicitly mentioned the possibility of using a groundwater heat pump (verbally, not in writing). Our planner explained that this ban is probably not legally enforceable anymore, as refrigerants approved for WSG 3a zones are now available. But the question is whether we really want to pursue this legally?
Soils:
We are very close to the Rhine, so the soils consist mainly of sand and gravel. It is still uncertain whether silty extensions from a nearby mountain range will be found at around 20 meters (65 feet) depth. And of course, there is the usual mineral content and flow velocity, which matched the conditions in neighboring projects.
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