General Contractor Offer - Heating + Sanitary = OK?

Normal price

If applicable, some savings can be made by going for 2 drillings. 210m is already a lot.

That was also my thought, hence the question about the heating load. Possibly the heat pump with over 8 KW is also somewhat oversized and one could choose a smaller model and would also need fewer meters of drilling. The result of the heating load calculation was not included with your details yet. Google "heating load calculation according to DIN 12831." There you will find examples of such a document. Alternatively, there is also an online tool in the pink forum to roughly calculate it. Some general contractors tend to oversize the heat pump. My GC also wanted to do that, but with some persuasion, I could have a smaller model.

What bothers me most is the withdrawal performance of just 41.9W/m. If the ground is really that poor, then maybe an alternative should be considered. 50-55W/m is the normal average, our drilling company plans with 45W/m as a safety buffer. With that alone, you could manage with 2 drillings. By the way, there are also companies in Saxony that do up to 250m with a single drilling. But at least 2x 99m is more or less the standard again.

What bothers me most is the extraction rate of just 41.9W/m. If the ground is really that bad, then maybe an alternative should be considered. 50-55W/m is the normal average, our drilling company plans with 45W/m as a safety buffer. With that alone, you could get by with just 2 drillings. By the way, there are also companies in Saxony that do up to 250m with a single drilling. But at least 2x 99m is more or less standard.

The "reverse calculation" is not quite correct. You have to subtract 20% (COP 5) from the heat output of 8.8 KW of the heat pump. These 20% of heat come from the supplied electricity, the remaining 80% from the ground. Then it's only about 33W/m. Either there are a lot of panic meters in it, or the underground is really not that suitable for a probe.

Addition to heating: - Heating capacity = 8.9 KW (according to Vaillant calculation)

We originally applied for 2x80 meters at the district office. However, the district office recommended doing 3 drillings of 70 meters each.

The approval has already been granted and the funding application has already been approved.