Energy consultant for a KfW 70 house costs 2,500€?

We recently had this discussed elsewhere as well. I consider the statement too general and therefore wrong and dangerous. It crucially depends on how the heat source can be accessed. Not only on the costs (drilling, etc.) but also on the geology. Is the ground suitable for regeneration, how deep can you go, what is the extraction capacity, etc.

Under suitable conditions, it may be possible to get the brine-water heat pump for a small additional cost, which could then also make it economical. However, it is not suitable for generalization, because even my case contradicts this universality.

You just have to like it. If you then have a malfunction and are sitting in a cold house, I want to see the emergency service that takes care of you. If you build the trench collector together with an HVAC technician, then maybe that's okay. But especially with central building technology, I would always keep service, customer service, etc. in mind.
And whoever thinks that a heating system (whether heat pump or gas) is super robust and never causes problems should consider why there are 24-hour emergency services.
But certainly a matter of personal attitude. It wouldn't be for me; I'd rather pay a little more once and not be left out in the cold when something does happen.

I consider the sales figures of the air heat pump a clear misdevelopment (I have one myself and am not happy with it!). The efficiency of most air heat pumps is not that great. Unfortunately, poor installation often worsens this even further (too large heat pump, buffer tank, poor design of underfloor heating, individual room controllers, no hydraulic balancing...).

The HVAC technician sells a heat pump heating system, and unfortunately the necessary planning is left out. (At the prices currently being charged for heat pumps, this is unfortunately not to be expected.)

Therefore, one should educate themselves and quickly realize that much has to be done by oneself and should be done before commissioning!

This includes:
- Having a heat load calculation done to determine the correct heat pump size – not by guesswork! This alone can save money – through a smaller model.
- Having the underfloor heating calculated with desired room temperatures and the lowest possible supply temperature
- No buffer tank
- No domestic hot water circulation

Many HVAC technicians have no interest in a "knowledgeable" heat pump customer.
But if you want an efficient system, you have to find one of the few specialist refrigeration companies or tackle it yourself. Unfortunately, for BAFA funding you need a stamp from a "specialist contractor."

Regarding service and maintenance for heat pumps. I believe you have not yet caught up with the current market situation. You are out of luck if you don’t deal with it yourself or have a good buddy at hand!

Let the factory service come for fault detection in case of performance loss. (Time required for troubleshooting, leakage tests, refilling refrigerant ...) For that money you could get a small Panasonic Geisha air heat pump.
And if you call the normal heating technician, he will check it, find nothing, or is not allowed to touch the refrigerant (since usually no refrigeration license is available)... He also calls the factory service... and you are doubly unlucky.

P.S. I have a Stiebel air heat pump myself. Even the HVAC technician recommended that in case of performance problems, it's best to have a specialist refrigeration company come. Anything else could mean a financial total loss.
A neighbor noticed performance loss on his Stiebel after 7 years. Factory service was there one day with one man, half a day with two men, plus travel, plus refrigerant. Cost nearly €2000! Afterwards, the heat pump was still defective and the compressor could have been replaced for €3000. Then you would have saved the €2000.... As of today, for that money, you get a more efficient current Panasonic Aquaera (also called Geisha). But even that can't perform miracles.

And with today’s low heat loads, one could also consider geothermal drilling if one does not want to do anything oneself.

Phew, that's an honest word. I already had the feeling, better take it easy, the company that was supposed to install this is rather rough and ready, they’ve known about gas since the end of the war. Son-in-law has one of those air-to-water heat pumps and already had to call Junkers factory service, it was still under warranty because the rough and ready installation company couldn't get the thing to heat without electric boost. Even though it should work at around 0 degrees. The Junkers guy managed to fix it, of course, but it seems like operating such a device is more like a better bachelor’s thesis.

A lot of what you write is correct, I just don't see the connection to my post.

All this fuss doesn't help you if the framework conditions don't allow for a ground-source heat pump. Just as an example: 450sqm plot, clay soil, rock from 3.5m down, drilling permitted by the water authority max. 30m.
So, now you.
I once posted the detailed offer for a drilling down here. I think it was 15k just for the drilling. That is also not economical even after the Bafa subsidy. And the trench collector is NOT an alternative for us because I primarily want to live and not play HLB. I consider the claim that HLBs can't get a heat pump running a myth. I find it somewhat presumptuous to assume that any random layperson could install and set up the heat pump better than an HLB who has been working only with one, max. one other manufacturer for years and has likely gathered a much broader range of experience through many customers.

The checklist you mention is absolutely correct; our HLB attaches great importance to it.

Perhaps the crux lies with the many HLBs who are dominated by GUs. In our LV (building with an architect), the checklist was included as a requirement. You can somewhat control this by awarding contracts individually.
Regarding the efficiency of heat pumps, you can look into the heat pump database. My conclusion would be that setting them up requires care, which often falls short (in sizing and installation). But to conclude from this that these things cannot be economical in general, I consider wrong. Moreover, a ground-source water heat pump can also be operated sufficiently inefficiently if it is dimensioned and set up incorrectly.

Incidentally, you have the same issue with controlled residential ventilation. It also must be properly designed so that it brings joy and not frustration. Bussystems the same. So in my opinion, it is less about the system itself and more about professional design and installation.

Unfortunately, gas is not available everywhere or the gas connection costs a lot. Moreover, gas urgently needs an exhaust system, which also has to be accommodated in the floor plan. This doesn't have to work everywhere. Otherwise, gas would actually be my choice simply because the system modulates so strongly and you basically have warm water until either the gas runs out or the water [emoji6]. Unfortunately, this is not the case with heat pumps.

15,000€ were common 8-10 years ago for large kfw60 houses. Our kfw60 house with 185sqm would have cost just under 12,000€ drilling costs. Back then, little to no BAFA funding. Today, due to the generally reduced heating load / heat demand, you get drilling for 6,000-10,000€. For clay, an earth collector makes sense. Nowadays 2 - 4 pieces necessary. Available as DIY or ready-made. The earth builder installs them during digging. Costs per piece with a good offer comparison 1,000€. You get a 4,000€ subsidy for the brine heat pump including earth collector, so nearly 3,000€ more than for an air heat pump. If I need 3 pieces, that's at least a break-even game. And per se, clay is a good heat storage, therefore.

15,000€ were common 8-10 years ago for large kfw60 houses. ... Today, due to the generally reduced heating load / heat demand, you get a drilling for 6,000-10,000€.

As I said, the drilling costs 15k here, offer from last November. I'm not saying that brine-water heat pumps are per se uneconomical, but simply ignoring the facts and postulating that drillings should cost so and so much doesn't get you anywhere. Likewise, it doesn't help to bring in...

With clay, a ground collector makes sense. Nowadays 2 - 4 pieces are necessary.

when there is not enough space. Yes, where suitable, brine-water heat pumps are a possible good solution. But not always.

It is available for self-build or ready-made. The earthbuilder installs it while digging. Cost per piece with a good offer comparison is 1000€.

I've already said my opinion about building a heating system yourself. Good for those who want to do it themselves, but that probably applies to very few builders.

You get a 4,000€ subsidy for the brine heat pump including ground collector, so about 3,000€ more than for an air heat pump. If I need 3 pieces that is at least a break-even deal.

4500€ (brine-water heat pump) vs. 2000€ (air-water heat pump) each including load management, makes a 2500€ difference, not nearly 3000€. Sure, nearly 3000€ sounds better, I could also say a good 2000€ [emoji6] I didn't understand the "if I need three" part? Three what do you need? How does that become a break-even game?!

And clay is per se a good heat storage, therefore

... but not a water storage. And guess how the soil regenerates when you’ve extracted a lot of energy from it? Water/precipitation is an essential factor, and its infiltration is difficult with clay. As I said, I have nothing against brine-water heat pumps and would even have liked to have one myself. It’s just not always an economical solution. That’s what's being suggested here. That bothers me because it ignores reality, since neither everyone has the required conditions (nice if it’s different), nor is the average house builder someone who assembles their own heating system. That’s all I’m saying [emoji4]

Basically, it's simple with the costs: if someone like the government or similar subsidizes something, it is never financially worthwhile. because it is subsidized so that someone will do it at all. the cheapest method is still gas and that's it. even today, houses are so well insulated, even with the cheapest method, that heating costs don't matter. all that stuff is nice and good, but it never saves money. don't forget that you also pay interest on the higher investment. instead of 600€ for gas, you pay 500€ for electricity and 200€ interest per year. that was a great deal...