ᐅ Requesting Feedback on Heat Pump / Quotation!

12 meters (39 feet) is really ridiculous. You don’t even need to consider a ring trench collector in that case.

Based on costs I’m familiar with, it would be 5,000 euros too expensive for me. Bavaria is more expensive, though, so that might be accurate. Once the heating load calculation is done, the 10.4 kW heat pump will likely be sized down to around 7–8 kW. If the 800-liter (210-gallon) tank with a fresh water station can be reduced to a standard size, that will also make it cheaper.

Or is there a specific reason for the 800-liter (210-gallon) tank?

boxandroof schrieb:

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

Is there a better solution for this?

boxandroof schrieb:

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

Thanks for the advice.

boxandroof schrieb:

The heat pump is certainly oversized. Is it at least modulating?

Unfortunately, I don’t know.

boxandroof schrieb:

The usual recommendations:
- no buffer tank
- design underfloor heating for a low supply temperature (<=30°C (86°F)), check everything yourself
- switch off single-room control at the latest upon moving in

I will keep that in mind and check accordingly.

guckuck2 schrieb:

12m (39 feet) is a joke. You don’t even need to consider a horizontal ground heat exchanger in that case.

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

guckuck2 schrieb:

Or is there a specific reason for the 800 liters?

Not that I know of. Maybe because we are 4 people and our installer is afraid someone might end up taking cold showers.

This is what the WWA states:

The use of a groundwater heat pump is possible in this area. There is already an approved groundwater heat usage nearby. In principle, according to the Water Management Act, there is no entitlement to a certain amount or quality of water. This means that every groundwater heat pump operator faces the risk that the efficiency of their own system can be significantly reduced by the inflow of already cooled water caused by later installations built close to their own system.

Groundwater is reached here under average conditions at a depth of 7-8 m (23-26 feet) below ground level (GOK). The flow direction is expected to be towards the northeast.

To ensure a reliable supply even during low water conditions, it is recommended to extend the borehole for the extraction well sufficiently deep. The possible final depth of a borehole here is approximately 11-13 m (36-43 feet) below ground level, as this reaches an impermeable clay layer that must not be penetrated.

Given the expected consistently gravelly soil structure, reinfiltration could be done via a simple soakaway well. However, the soakaway base of this well should be at least 3 m (10 feet) below ground level to reliably prevent any impact on neighboring buildings from the infiltration cone.

neubau2019 schrieb:

Not that I know of. Maybe because there are 4 of us and our plumber is worried someone might have to take a cold shower.

Then that also goes on the energy waster list. Use a 200-300 liter (50-80 gallons) tank, that’s plenty.

Heat pump one size smaller
Storage tank at a normal capacity
Fresh water station then becomes unnecessary.

Overall, it should be 2,000-3,000 euros cheaper. Better to invest that money in closer spacing of the underfloor heating pipes to achieve a lower supply temperature.

Or switch providers, because so far everything has been done wrong.

neubau2019 schrieb:

Is there a better solution for this?

The simpler alternative to a fresh water station is a standard, properly sized (200-300 liters (50-80 gallons)) domestic hot water tank with a heat exchanger of at least 2m² (22 sq ft).
Regarding hygiene and legionella, please research and decide for yourself. Even with a high (>50°C (122°F)) and therefore less efficient storage temperature, such a tank may be more cost-effective.

From my point of view, it is more important to ensure that no buffer tank is installed in the heating circuit, that the underfloor heating is well designed, and that the heat pump is not oversized. If possible, it is also advisable to avoid circulation.

neubau2019 schrieb:

With the expected continuously gravelly soil structure, recharge through a simple sump well could be possible.

Regarding the lift principle: I am not sure whether this is a common option offered by manufacturers or heating engineers, other forums might provide more expertise on this. In any case, it does not appear to be planned.