Trench collector brine-water heat pump or air-water heat pump?

Hello everyone,

we were at the first BU yesterday. He promptly dismissed the heating issue - no gas - but gave us some contact addresses. The house has about 190 m² of living space and a heating energy demand of 6600 kWh/a or about 6 kW heating load requirement. So far, we have planned to install a ground-source heat pump with trench collector, but the BU rightly pointed out that, for example, he would like to have maneuvering space around the house. In the pink forum, there is a community that strongly supports DIY trench collectors and says that the trenches including material would be feasible for 2,000 €. Including a gross price of 10,000 € for the pump, that would be 12,000 €. The air-to-water heat pump would already cost at least that much for the pump alone. Unfortunately, we are already somewhat overwhelmed with the house planning and don't know if we would trust ourselves to do the DIY. Does anyone have experience with how much it costs if you outsource the digging and laying? Regarding consumption, we have figured out a factor of about 1.5. So the air-to-water heat pump is about 50% more expensive to operate than the ground-source heat pump, but we wouldn't have to dig anything (absolutely that would be about 180 € per year). It is also unclear to us whether installing photovoltaics would be beneficial or not (we are skeptical).

Thanks for your experiences and tips.

You first have to clarify whether a trench collector works for you

In our case, it simply wasn't the case (similar heating load & heated living area) - although everyone previously advised it. Now there will be a 120-140m drilling. In the end, I even prefer that because it definitely works - I found the trench too uncertain. Additionally, more effort needs to be invested in planning & coordination with the shell builder - depending on the plot layout.

The area would be there - if necessary in the garden behind the house. I am just a bit worried whether the coordination and planning would work out. Drilling is too expensive for us - we would rather install an air-to-water heat pump.

How much area do you have of UNDEVELOPED land? What type of soil?

Meltwater sand/gravel sand and gravel loam. About 650 m² undeveloped - but this also includes the driveway on which the construction road currently lies (without which there are still about 580 m²).

Ok, that should really be enough of the basic data.