Heating type for new construction - Which is the best?

Do you know where you can see these geology maps that show whether a geothermal heat pump makes sense or not?

Yes, for NRW there are maps. Just google "Geothermie NRW". The entire country is divided into classes there. Starting from 4 it gets tight, above that it works. Apart from that, there can be regional restrictions, e.g. in water protection areas or if the drilling would connect two groundwater layers, etc., but the Geological Service or the approval authority will tell you that, because: The geothermal yield can be calculated for the specific location by the Geological Service NRW for 200-250€. Nobody knows it better, especially not for such a low price. If you also know the heating load, the drilling meters can be easily calculated. Everything else is just guessing.

One drilling meter costs about 50-65€. Of course, 100m is more manageable than 300-350m, which would be realistic for the assumed 18kW.

The whole country is divided into classes there. From 4 onwards it gets tight, above that it works.

Only at a drilling depth of 100 meters do you reach class 3c as I see it.

Just now, an alternative provider for house construction was here, who said he had checked that one can definitely work there with a geothermal probe.

Don't let yourself be put off by that, a villa for 800,000 euros and a gas connection I find strange in 2017. And you can also do several drillings, no problem. They don't want to do it there because it is still a niche product.

And you can also make several drillings, no problem. They are not interested in it, because it is still a niche product.

I don't know if they are not interested. They had it in the service description from the very beginning on their own. Now they just think you have to go so deep that it becomes uneconomical....

What do you mean by several drillings? Two probes next to each other?

Several drillings will also cost twice as much. I simply suspect that it is due to the economic viability.

What do you mean by multiple boreholes? Two probes side by side?

Yes, instead of drilling 100m, you can also drill 2x 50m, however the two boreholes must have a certain distance between them (8m ?!). I no longer know who it was, but someone here in our circle (Bavaria) said that in Bavaria one is generally not allowed to drill deeper than 100m... no idea if that’s true, but in that case you would have to make several boreholes. For 300m, for example, 4x 75m or or or

A borehole costs 10-15,000