montessalet
2018-05-31 13:17:54
- #1
Nothing personal, but the statement is simply wrong in its generality. The ground-source heat pump stands or falls with the development of the heat source and its costs. These are, for example, very different (regionally) for a deep borehole. About half a year ago, I posted my offer for the drilling here in Franconia. The drilling was at a good 15k. The heat pump itself, meaning the unit, is comparable, but not the development. And for the 15k you can, if you want, also deduct the 5k subsidy, so there are still 10k additional costs that will not amortize nearly as quickly.
Regarding the regeneration capability: the ground apparently regenerates through precipitation and moisture – that’s how a geologist once explained it to us. So if the soil can hardly absorb precipitation (clay) and/or it rarely rains, it can become problematic. This has apparently become an issue for a few builders of our architectural office. They wanted a ground-water heat pump against warnings, and now they are struggling with the fact that under the mentioned circumstances, not enough energy can be extracted from the ground anymore.
Not to be misunderstood now: I would always opt for a ground-water heat pump if it would somewhat pay off for us and the framework conditions fit. Unfortunately, they do not. But that the ground-water heat pump is a universal tool and works always and everywhere is simply not correct, and I want to raise awareness for that. In most cases, however, it should be a good solution if the additional costs for drilling are within reasonable limits. And here, too, the local situation plays a role. Can you get away with one borehole because you are allowed to go deep enough? Or do you have to fractionate, for example, set 4 or even 6 boreholes, which is significantly more expensive.
My generalization is correct in most cases – but it is at best a (possibly misleading) simplification. You are of course right about that. Especially the points you mentioned are of course decisive:
- Soil conditions (regarding the properties needed for a ground-source heat pump)
- Costs of the borehole(s).
The first point can be a deal-breaker, the second is only about the amount of costs.
If the soil conditions allow it and the offer for the drilling is "reasonable," I would clearly recommend the ground-source heat pump. The noise level of the air-source heat pump can really get on your nerves – and that is sometimes worse than the "few euros" of additional costs.