ᐅ Geothermal energy or air-source heat pumps, any experiences?

Hello,
I have already read quite a bit about the two options mentioned above as alternatives to gas.

Now I would like to hear personal experiences.

Geothermal energy:
I know it is quite expensive, which is not a problem for us, but the following questions came up:
- Is the technology really mature?
- How prone to problems is the technology based on your own experiences?

Air-source heat pump:
This is supposed to be cheaper, but I often hear that it can be quite noisy.
I know similar units from the USA, but as air conditioners, and they were quite loud.
- Does the noise bother you?

I’m curious to hear what pros and cons you see for both systems.

Thanks in advance!

I decided to install a horizontal ground heat exchanger myself, extracting geothermal energy from the ground. Thanks to doing it on my own and the government subsidy, I almost reached the price level of an air-source heat pump.

From personal experience, you will almost always hear the same from homeowners: theirs is the best.

j1985 schrieb:

Geothermal energy:
I know it can be quite expensive, which is not an issue for us, but the following questions came up:
- Is the technology really mature yet?
- How reliable is it based on your own experience?

Air source heat pumps:
These are supposed to be cheaper, but I often hear they can be quite noisy.
I know similar units from the USA, where they are used as air conditioners, and those were quite loud.
- Does the noise bother you?

The heat pump technology itself is basically the same; the difference lies in the connected heat source.
I see the advantage of geothermal energy in better, year-round efficiency. The underground probe is a passive, simple component embedded in concrete. What could really go wrong? Maybe topping up the antifreeze solution every few years, but not much else.
The outdoor unit of an air-to-water heat pump takes up space and affects both appearance and noise levels. Although I don’t want to exaggerate the noise unless the cheapest, noisiest model has been chosen. This part is active, has moving components, and is exposed to weather conditions. Unlike geothermal systems, I see a higher likelihood that replacement parts will be needed and maintenance performed.

In our area, there is no gas supply, so everyone uses heat pumps. I would estimate about 60% have air-to-water heat pumps, with roughly half of those installed indoors and half outdoors, and 40% use brine-to-water (ground source) heat pumps with a probe. We also have the latter.
After accounting for current subsidies, it was maybe about 2,000€ (approx. $2,200) more expensive than an air-to-water heat pump. The arguments above were more than enough to convince us to choose this option. Just the appearance on the building alone was worth it for me. Energy costs are not even a factor to consider seriously, but when replacement is due, I can continue using our geothermal heat source, whereas an air-to-water heat pump usually needs a full replacement. At that point, geothermal will clearly be the better choice. But time will tell.

More important than the heat source is the quality of the planning: sizing, calculation of heating surfaces, hydraulics without a buffer tank, and no individual room control.

I would primarily focus on these aspects if I were you. A well-planned air-to-water heat pump outperforms an average-designed ground-to-water heat pump.

I would recommend a trench collector with subsidies if feasible, especially in colder regions. The price/performance ratio is unbeatable. Ground-based systems can sometimes cause issues, whereas with an air-to-water heat pump, resolving such problems is generally much simpler.

My experience with our air-to-water heat pump (without an indoor unit) has been excellent; it is inaudible indoors despite being installed right in front of two windows. From around 3°C (37°F) outside, it becomes slowly audible. If the neighbor is very close, you need to consider noise levels carefully and either choose very quiet units or implement additional construction measures.

Compared to a trench collector, our air-to-water heat pump uses an estimated €50 to a maximum of €100 more electricity per year.

In the end, it depends on how much personal effort/planning you can invest and what kind of offers you receive.

Thanks for your comments

I’m also still just at the very beginning and sometimes feel really overwhelmed. I constantly have to look up technical terms.

Can you recommend a good website where beginners can get a solid introduction?
I feel like I haven’t found the right resource yet....
Thanks in advance!

Just google "there is no fire burning inside a heat pump" or "Aquarea Club"