Feedback on heat pump / offer requested!

12m is a joke. You don’t even need to consider a ring trench collector.

Based on costs known to me, it would be 5000€ too expensive. But Bavaria is more expensive, so that might be true. Once the heating load calculation is done, the 10.4kW heat pump will probably become a 7-8kW heat pump. If the 800l tank with fresh water station can be reduced to a normal size, it will also get cheaper.

Or is there a reason for the 800l?

Storage is necessary for the fresh water station, can be done. However, storage should not be used as a buffer for the heating circuit.

Is there a better solution for this?

Groundwater: the pump consumes a lot of electricity and reduces the otherwise good efficiency (if everything goes well). There are options to avoid this with two boreholes and the siphon principle. Definitely insist on that.

Thanks for the tip.

Heat pump is certainly oversized. Is it at least modulating?

Unfortunately, I don’t know.

The usual advice:
- no buffer storage
- plan surface heating for low (<=30°) flow temperature, check everything yourself
- disable single room control at the latest upon moving in

I will keep that in mind and/or check.

12m is a joke. You don't even need to consider a trench collector for that.

Did you mean more drilling meters? You should calculate about €250 per meter for the well.

Or is there a reason for the 800l?

Not that I know of. Maybe because there are 4 of us and our installer is afraid someone will have to shower cold.

This is what the WWA says about it:

A groundwater heat pump usage is possible there. An approved groundwater heat usage is already located in the immediate vicinity. In principle, according to the Water Resources Act, there is no entitlement to water of a certain quantity and quality. This means that there is a risk for every groundwater heat pump operator that the profitability of their own system can be significantly reduced by the inflow of already cooled water caused by installations built nearby later.

Groundwater is reached there under average conditions at a depth of 7-8 m below ground level (GOK). The flow direction is presumably expected to be towards the NE.

To ensure a permanently secure supply even during low water conditions, it is recommended to develop the borehole for the extraction well sufficiently deep. The possible final depth of a borehole here is about 11-13 m below GOK, because then a sealing clay layer is reached, which must no longer be drilled through.

With the expected continuously gravelly soil structure, reinfiltration could be carried out via a simple shaft well. However, the infiltration base of this shaft well would have to be at least 3 m below ground level to reliably prevent impairment of neighboring buildings from the seepage cone.

Not that I know of. Maybe because we are 4 people and our installer is afraid someone has to shower cold

Then that is also an entry on the efficiency killer list. Take a 200-300l storage tank, that’s more than enough.

Heat pump one size smaller Storage at a normal level Fresh water station then unnecessary.

It should be 2-3k€ cheaper in total. Better invest the money in closer installation of the underfloor heating to achieve a low flow temperature.

Or change the provider, because he has done everything wrong so far.

Is there a better solution for this?

The simpler alternative to the fresh water station is a normal suitably sized (200-300l) hot water storage tank with a heat exchanger from 2m². Regarding hygiene/legionella, please inform yourself and decide independently. Even with a high (>50°) and thus inefficient storage temperature, a tank may possibly be more economical. From my point of view, it would be more important to ensure that no buffer is installed in the heating circuit, that the underfloor heating is well planned, and that the heat pump is not oversized. If possible, circulation should also be avoided.

With the expected consistently gravelly soil structure, recirculation could be done via a simple shaft well

Regarding the lifting principle: I don’t know if it is a common option among manufacturers or heating installers or not, there are other forums that provide more expertise on this. In any case, it does not appear to be planned.