ᐅ Experiences with the slinky ground loop collector in the Bavaria region?

NeuerBauherr schrieb:

Regarding point 1... you mainly find positive feedback, which made me a bit suspicious. If the trench collector is so good, why isn’t it already standard?

As someone already mentioned, it is quite common in the south and in Austria. Currently, it’s still somewhat "special." There are not yet many companies offering it, and it originated from another forum where most people install the trench collector themselves (and design everything with the trench planner, etc.), which is not for everyone. It’s not difficult, but you do need some trust that it works when you go this route—see your post. But why wouldn’t it work? It’s basically just a ground collector installed in a trench, which means relatively little installation effort with very good ground energy capture.

NeuerBauherr schrieb:

Regarding point 2... I’m somewhat skilled with DIY, and also enjoy operating smaller excavators... We haven’t yet decided whether to do the excavation ourselves or hire it done.

As already mentioned, here’s a quick tip: big excavator! Don’t underestimate the excavation work—you might spend 1-2 hours on the excavation with a large excavator, but with a mini excavator it can take days... Costs are usually more effective with a larger excavator as well.

NeuerBauherr schrieb:

Regarding point 3... wow, that’s also my goal: achieving a high seasonal performance factor with low energy consumption.

With your property and the huge area, achieving a high seasonal performance factor is normally no problem at all. Do your planning in the other forum, or start your own thread there, so the planning can’t go wrong.

NeuerBauherr schrieb:

I know that choosing the heat pump depends on the heating load, but I’d still be interested to know which manufacturer(s) you are using, and which models? Also, do you possibly have a photovoltaic system combined?

I’m currently running a fixed-speed Stiebel. It has worked without problems so far; in hindsight, I might have chosen a modulating model, but often that’s a matter of preference. The brand is almost secondary nowadays—all major manufacturers are reliable and have extensive experience. What’s important is that your heating installer knows the system well and, above all, that the underfloor heating is properly designed, because a poorly designed underfloor heating system will cause the heat pump to cycle excessively, which often shortens its lifespan. A well-configured heat pump, however, lasts a very long time.

Regarding passive cooling, there are differences in additional costs. The extra cost should usually not exceed about 1,500€ (all-in) (around $1,600), though with me it was even cheaper—of course, it also depends on your heating engineer’s approach. Even if someone suggested you could equip the whole house with split air conditioning instead... no, that definitely isn’t comparable. In the forum where the trench collector originally comes from, you’ll find a lot of positive feedback on passive cooling, including practical tests with assessments of its effectiveness. The conclusion: it works well.

Of course, you shouldn’t compare it directly with an air conditioner. There is no active dehumidification, and the cooling capacity is lower. But it doesn’t just cool the room air; it continuously absorbs heat from the large heat stores of the house (screed, walls, concrete ceilings, etc.) and keeps the indoor temperature cool. It’s not an air conditioner but rather an ecologically friendly way to keep the house cool in summer, and it’s almost free to operate.

Also, the trench collector isn’t just for cooling. Even without cooling, it makes absolute sense because it improves the overall system efficiency. The costs are very low—you basically just "embed pipes in the concrete." That’s all. Just the standard heating pipe installed in the ceiling, nothing more.

Tego12 schrieb:

Even if my predecessor says you can equip the whole house with ductless mini-split air conditioning...

In my post, I wasn’t referring to air conditioning the entire house. I meant the piping installation to enable future retrofit of the units. Of course, a split air conditioning system is generally more expensive overall. Otherwise, as mentioned, it’s a matter of preference. I like both approaches but for now, I’m having the piping for the split system installed—or doing it myself (fortunately, my HVAC technician is very relaxed about this). If I ultimately decide to use only passive cooling, I can privately purchase the heat pump module later on and won’t have spent more than if I had bought it directly from the HVAC contractor (there’s about a €1,200 difference in our quote).

BKA is correct. It’s also important for low supply temperatures and more even heat distribution (which is said to feel more comfortable), and costs under €1,000 (about $1,100) depending on the house size plus an afternoon of labor.

Yes, that is actually quite important... finding a heating engineer who is willing to handle everything. I initially had a few discussions with mine, as he had never heard of a trench collector before. In the end, I offered to be a reference for him if he wants to offer or implement this solution for other clients. Together with a clearly defined transition point (input and output manifold), this was acceptable to him.

Strahleman schrieb:

Passive cooling works, but including the ground-coupled ventilation system (BKA) in the installation, it’s not cheaper than a split air conditioning system. We initially wanted passive cooling as well, but eventually switched to air conditioning. The discomfort in summer is mainly caused by humidity, and passive cooling can’t help with that.

If you now move away from the ground-coupled ventilation system (BKA) and switch to a split air conditioning unit, how does that generally work? Is the unit installed in the basement next to the mechanical ventilation with heat recovery (MVHR) system, adding cold air to it, or how should one imagine the setup?

Because implementing a BKA is not really associated with high effort and costs. I would expect equipping a house with an air conditioning system to be more expensive. Especially since you then have an outdoor unit in the garden, which you could nicely avoid with a ground-source heat pump.

The controlled residential ventilation and air conditioning will be two separate systems that are not integrated. We will install a classic ceiling or wall unit in the rooms to be cooled, which can be switched on as needed.

Yes, a split air conditioning system is more expensive compared to a water-based cooling system. However, we will initially only prepare the infrastructure so that the air conditioning can be installed relatively quickly if needed. After all, some copper pipes need to be routed inside the walls for this. I will probably also include the water-based cooling system on the ground floor, since it only involves three pipes of 20x2 millimeters (about 0.8x0.08 inches), each approximately 70 meters (230 feet) long. This gives us three options:
1) Do nothing and leave everything as it is if the temperatures are comfortable for us.
2) Retrofit passive cooling using the heat pump and activate the water-based cooling system (alternatively, use the water-based cooling to reduce the supply temperatures even further).
3) Retrofit the split air conditioning system. In that case, I consider installing photovoltaic panels mandatory.

The outdoor unit is less of a concern for us. As the name suggests, it will be installed outside, on the north side next to the front door. This way, it is only visible when entering or leaving the house and does not take up space in the garden.