ᐅ Comparison of Groundwater, Ground Source, and Air Source Heat Pumps

https://www.hausbau-forum.de/threads/lwwp-aktueller-verbrauch-und-daten.36616/post-479572

Read from here, this was about the cost comparison between drilling and a standard heat pump.

Basically, hire an energy consultant who can provide a room-by-room heating load calculation, including the pipe spacing for the underfloor heating, and not using fictional room temperature values but realistic ones such as 22°C (72°F) for the living room, 24°C (75°F) for the bathroom "without additional heating, only wall heating via underfloor heating," at least 20°C (68°F) for the bedroom, etc.

Then choose a modulating unit that qualifies for BAFA funding.

So one that has a COP of 4.0.

Then check whether geothermal energy is feasible and what your region requires for drilling permits/planning permission. Here, differences of 10,000 euros are possible. Until you save that amount, you could be heating for many years.

If you have a large plot, consider a trench collector (horizontal ground collector), where a lot of DIY work is possible.

With 140m² (1,507 sq ft), fortunately, there isn’t much that can go wrong.

sub-xero schrieb:

The design of the underfloor heating is important, that much I understand. It has to match the heat pump. What exactly matters in this, I still need to research (any tips/links would be appreciated).

No, that is incorrect. The design of the underfloor heating must fit the house and your desired temperatures, and that is where the biggest mistakes often happen.

Which heat generator supplies it is irrelevant at first.
https://www.hausbau-forum.de/threads/Erdwärmepumpe-fuer-ein-kleines-erdgeschossiges-einfamilienhaus.38696/post-486058

From a purely financial perspective, a gas heating system would be the best choice—ideally with classic radiators attached... but this discussion isn’t about the cheapest solution, it’s about heat pumps. From reading Bookstar’s posts, it seems he is not a fan of heat pumps, especially not geothermal heat pumps. I am a big supporter and have installed one myself in our new build (or rather, it will be installed soon).

In general, an air-to-water heat pump is sufficient for many house sizes, as there are different capacity classes available. I would worry less about that. More important, as T_im_Norden already said, is the proper design of the underfloor heating system and the U-value (thermal transmittance coefficient) of your house. Roughly speaking, for underfloor heating you should use at least 16 x 2mm (5/8 x 1/8 inch) pipes, with a spacing of 10cm (4 inches) between pipes (less spacing is fine in bathrooms), and a maximum length of 80–90m (260–295 feet) per heating circuit. Any deviations from this will increase your flow temperature and therefore your heating costs.

With a groundwater heat pump, the soil conditions and groundwater level play a crucial role. If the groundwater is too deep or difficult to access, drilling costs can become very high. If your soil is suitable, the water authority grants permission, and you don’t mind the additional costs compared to a geothermal heat pump, then go for it. Personally, I find the extra costs too high even with better efficiency. With the roughly 10,000 euros of additional investment you mentioned, one could pay an extra 300 euros per year in heating costs for another heat pump over the next 30 years and still come out cheaper.

I find the geothermal heat pump financially attractive, especially if you have decent DIY skills and a suitable plot to install a horizontal ground loop yourself. For us, including the digging work, the installation by three people (two pipe layers and one excavator operator) took less than a full day and cost under 2,500 euros. There is some additional effort for commissioning (about 1,500 euros) compared to an air-to-water heat pump, but the extra costs are worth it to me for the better efficiency and annual performance factor.

If you choose a heat pump, go for a ground-source heat pump. It is at least reasonably efficient in operation. Air-to-water heat pumps become inefficient precisely when the outside temperature is very low (due to defrosting) and you need the most energy. Photovoltaic systems should be as large as possible with a steep roof pitch. When you need the most (heating) electricity—in winter—the sun is at its shortest and lowest. If there is snow and ice on the 22° (22 degrees) roof, even more so… From a purely financial perspective, this is all an expensive game, as far as investment and operating costs are concerned. Natural gas is currently unbeatable. It just makes Mr. Putin rich. The best energy, in the long run, is the one your house doesn’t lose.

Using gas was meant seriously, as it is by far the cheapest and most hassle-free way to heat a home.

Heat pumps are still very expensive and often prone to faults. Of course, you can get lucky and have a unit that runs well. Durability is also an issue. Often, after 5 to 10 years, a major component breaks down.

Air-to-water and ground-source (or brine-to-water) heat pumps no longer differ that much in efficiency.

If a heat pump and photovoltaic system with a battery are already planned, I would reconsider controlled residential ventilation and opt for KfW40+ standard right away.