ᐅ Planning/Preparation for a Deep Foundation Drilling

Created on: 27 Sep 2015 10:54
F
FloLiX
Dear forum members,

I am planning to build a single-family house with a heat pump and want to carry out a deep drilling for this purpose.

Problems in my view – possible legacy issues from mining (Ore Mountains).

In another post, I also read that the local water authority has objected:

“Now the local water authority has thrown a wrench in the plans and does not allow deep drilling.”

Therefore, I would like to know where problems generally arise and how these can be identified early and avoided.

Best regards,
Florian

PS: The construction company believes that deep drilling would not be problematic.
PPS: I would prefer not to be surprised by insurmountable problems after the planning process.
Ecart21 Oct 2015 10:13
toxicmolotow schrieb:
I don’t find the price too high now, but I paid significantly less for 10 meters less (and I mean about 2,000 euros less, NRW Rheinland).

1. Quote for 110 m at our place:

Drilling: €5,712
Connection work: €982

If needed, I can probably inquire for you. | Save €2,000
S
Saruss
21 Oct 2015 10:22
There are many factors that make these prices "incomparable"; the type of probes, the number of boreholes, the backfill material, accessibility, the length of the connection/what is included (e.g., maintenance shaft for external venting or not), and so on. More information is needed.
S
Sebastian79
21 Oct 2015 11:58
BeHaElJa schrieb:
How many meters have you drilled? The building authority recommends 70 to 90 meters of double U-loop probe. The drilling contractor suggested 100 m and assumes a heat extraction rate of 50 W/m (which we don’t even have). That confuses me a bit.

Then ask him why he is making assumptions that you don’t have. It doesn’t help you to know our values – it has to be planned individually for each building project.

We have 44 W/m and the drilling length was sized based on the heating load (1 x 140 m (460 feet)). As far as I know, you haven’t done that yet, right?
L
Legurit
21 Oct 2015 12:08
Yes, there is a heating load. It is 5.4 kW plus hot water (assumed 1 kW). What was completely off was the room heating load. According to effiziente-Wärmepumpe.ch, at 39 W/m² (12.2 Btu/ft²·h) and a COP of 4.6, including hot water, this would mean 125 meters (410 feet). However, the drilling company now suggested 100 meters (328 feet) – the geothermal report (LBeg) actually mentions even less (based on our data).
S
Sebastian79
21 Oct 2015 12:09
Then just order 125m (410 feet) – You are the one paying, so you are the one in charge
L
Legurit
21 Oct 2015 13:53
Not so simple again... 6 kW is offered – additional meters can be "purchased." Now I need to find out what it means if there are not one but two boreholes. The whole trade is a disaster – or rather a stress test. We have now ordered 20mm (3/4 inch) pipes for the underfloor heating, based on advice from the pink forum – but now everyone suddenly says that installation doesn’t work well with them.
We remain curious.