Air-to-air heat pump vs air-to-water heat pump vs ring trench collector - differences

Hello,

I am currently facing the question of how the energy for the heating should be generated.

Here in the forum, I came across the ring trench collector, which I find very interesting.
In conversations with two prefab house providers, I mentioned that I am considering generating the energy via a ring trench collector, and both times the response was, "Ring trench collector, we’ve heard of it, but never done it."
In the offer, there was once an air-to-water heat pump (Luxhaus-KfW55) included and once a LLWP with controlled residential ventilation (Streif Haus house-house KfW40).
The house should have 2 levels, no basement, about 190 m², fairly flat plot without special features.

I wonder how the ring trench collector differs technically and in terms of price from the air-to-water heat pump.

Is the technology in the house the same, or do other things have to be considered, also with regard to the size of the system, design of the technology in the house?
Is the difference essentially that instead of the outdoor unit of the air pump, I dig the trench and lay the pipes?
What is the price difference?

How is the long-term difference in energy consumption? The air pump has to be continuously operated with electricity to draw in the air; how is it with geothermal energy from the ring trench?

Finally, the question of belief regarding the air-to-air heat pump:
The Streif Haus house salesperson said, in response to my question about how much more it would cost if I took an air-to-water heat pump instead of the air-to-air heat pump, that the additional costs would be around 10,000 euros. Is that realistic?

The Streif house salesman said in response to my question about how much more it would cost if I took an air-to-water heat pump instead of the air-to-air heat pump, the additional costs would be around 10,000 euros. Is that realistic?

That can be accurate, although the additional costs are not due to the different heat pump itself, but rather the underfloor heating that was saved with the air-to-air heat pump.

Ring trench collector + brine-water heat pump is (simplistic calculation, due to own contribution..) cheaper than an air-water heat pump, because the subsidy is significantly higher. For example, I built the ring trench collector myself, it cost me less than €2,500 (including pipe, manifold, rental for excavator + driver, house entrances, etc.), but I received €5,500 in subsidies (so in total got the collector for free + €2,000 pocket money ; ).

Advantages: Passive cooling in summer possible (practically free, no huge effect, but certainly an advantage in warm periods), efficiency higher than with air-water heat pump, durability (the collector itself will outlive you by far; brine-water heat pump is said to have a longer lifespan because the heat transfer medium is more constant ....), and what was very important to us: No ugly outdoor unit of an air-water heat pump! (air-to-air heat pumps were out of the question anyway, because they are clearly less efficient compared to air-water heat pumps).

Regarding your electricity question: A brine-water heat pump of course also runs on electricity, but produces more heat energy per kWh of electricity.

Air-to-air heat pump does not have underfloor heating. Fresh air is drawn in, heated with heat recovery, and whatever is still missing is added by electricity at the air outlet. Like a small hairdryer. Hot water only by electricity. Because the underfloor heating is missing, that can amount to 10,000 euros.

Air-to-water heat pump The air-to-water heat pump has a refrigerant circuit and a compressor. Works like a refrigerator but reversed. Usually, underfloor heating is connected. The hot water is also produced by the pump. Only at very low temperatures does the performance no longer suffice.

Ring trench collector is more efficient. How much that is in euros, no idea.

I would not install a pure air-to-air heat pump. Air-to-water heat pumps can also be installed without an outdoor unit.

Air-to-air heat pump is the biggest rip-off since the invention of the surprise egg and should be avoided. It is only topped by an exhaust air air-to-air heat pump.

Air-to-water heat pump is state of the art, can work well if everyone involved (including the end user) knows what they are doing. However, in case of poor design and usage, it is a money pit. Engaging with the subject matter yourself is an absolute must.

Trench collector is great, direct competition to other ground sources, but very simple and cost-effective to develop. If your developer agrees to it, just document it with photos as a thank you on their homepage. We didn’t do that only because we heard about it too late. That’s something where the developer can learn something, which they can then offer as a unique selling point to their future customers.

: Can you share how you proceeded with your ring trench collector? Did you choose the heat pump yourself? Did you order the collector pipe(s) prefabricated? Sorry if there is already information about this here in the forum. Thanks! mini