Experiences with brine heat pump

I am posting my offer here for 2 x 70 m, double U-probes including connection work; assumption 7 kW heating output... what do you think about the points listed under "if necessary," do I need them??? Cost 3900 extra....

You can see the differences. The applications cost €70, for me twice because of mining law due to >100m depth. Equipment setup €250 and not €1350. Pressure testing €120 instead of €450. Nobody needs a geologist here either. I don’t need a distribution shaft because there is only one probe. Besides, they seem quite expensive to me. You need the container if you are not allowed to discharge the drilling sludge into a body of water or don’t want it on your property... but the container here only costs €270 including disposal. In addition, I already have the water included, which in your offer will have to be provided by the builder (although that is only peanuts).

Do I understand this correctly? If the heating load calculation results in 6 kW, the drilling is only done for 4.6 kW? I had always assumed that the drilling would then also be for 6 kW or a bit more generous, maybe 6.5 kW.

Regards
denz

That's how it is. Required heating power / (1-COP).
The drillers here calculate with 80% to 75% and design accordingly. Some add a safety margin. I would also do that, maybe 5m more, even if it's actually not necessary, especially if improved grout material is used. But nobody wants to be annoyed afterward about saving 300€, in case the probe doesn't work so well. Nobody looks 100m deep into the ground beforehand, geo maps or not. And no one in a single-family house can afford corresponding tests.

Cool, a link to a state government site (Förderung für Erdwärme in NRW) is removed with reference to the forum rules, but I see links to some advertising partners under every post. The embedded external sources slow down the site so much and the advertising banners make the forum almost unreadable.

I'll just withdraw for now - just wanted to help...

Well, I don't know how it is in other federal states, but NRW has a worldwideweb.geothermie.nrw.de portal *cough* where you can check how the withdrawal performance at a drilling site will most likely be. I assume there is something like this everywhere.

We are at the borderline between 2c and 2b (so lower good) in terms of "yield" with short probes; by the way, the yield decreases with longer probes in our case. If it turns out that the yield shows a weak average or is even critical, I probably wouldn't waste any thought on something like that.

Based on what has been posted here, I was probably not wrong that geothermal energy with drilling is not economically feasible in southern Germany. Especially because modern air-to-water heat pumps now achieve a COP of over 4, which further worsens the amortization of geothermal energy significantly. Moreover, modern systems have massively reduced noise emissions. Even mine can only be heard when standing right next to it.

It's a pity, actually a great technology, but no longer simply usable!