ᐅ Groundwater Heat Pump – Disadvantages?

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.)

Yes, that is the risk. Plus the issue of obtaining a building permit (planning permission). But if it works, in my opinion, it is one of the best heating systems.

If everything fits, why not. For me, it would be too risky because too many factors would have to be just right: water mineral content, soil composition, flow rate, water use permit / license. I wouldn’t put much stock in the claim that it could be done 300m (980 feet) away. That’s probably similar to soil surveys. Very little in geology behaves consistently. I’ve also had bad experiences. Our neighbors right next to us (about 10m (33 feet)) have no rock and zero water in their excavation pit. Ours fills up completely, so we need dewatering. The neighbor manages without soil replacement, while we have clay and rock. It would be too much of a gamble for me. But if it works, it would be a good form of energy generation.

What are the disadvantages of a ground-source water-to-water heat pump? This way, you avoid all the water quality issues and the open system that is typical for water-to-water heat pumps.

On the other hand, you probably need more drilling meters, but you get a closed system.

At least, this should be an adequate alternative in an emergency.

It is a groundwater protection zone 3, but the local environmental authority has explicitly pointed out the possibility of such a heat pump. However, a ground-source heat pump is therefore excluded.

Do you know anything about the maintenance requirements (possibly in comparison to other systems)?

No one can say that definitively. First, a water analysis is important to ensure proper planning.