Internal heat pump in the basement not possible due to groundwater?

I give up. However, I completely agree with .

Here, one smoke screen after another is being set off.

@ No one is taking away your opinion, only if you do not want to follow the facts that even politics recognizes, you ignite the smokescreens.

Just take a look at your thermal insulation certificate according to DIN 18599 (possibly old DIN 4701) or the TGA calculation for heating load according to DIN[B] 12831 for your split heat pumps, the facts are there. Your heat pumps were designed based on nothing else.

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Attention many manufacturers refer to DIN 15450 for positioning. The DIN EN 15450 sets criteria for the planning of heating systems in buildings that operate only with electrically powered heat pumps or with heat pumps in combination with other heat generators. Furthermore, topics such as power supply, positioning, noise emissions, heat supply, and dimensioning are explained. However, the standard explicitly does not consider the planning of these systems. It only applies to the heat pump itself, the interfaces to the heat distribution and heat transfer system (for example buffer system), and the control of the entire system. Systems that are mainly designed for cooling and systems that can operate simultaneously in cooling and heating mode are also not covered in the standard.

Regarding indoor installation and duct routing, there are enough court rulings on heat pump removals due to inefficiency. It is therefore possibly recommended to have confirmation that no flow short circuit can occur, which even a layman can test with a small fog machine.[/B]

Okay, I can partly understand the reasons that speak in favor of an indoor installation.

Have you made any progress with the manufacturer regarding the question of wall penetration with pressurized water?

What does your main contractor say about the conflict of interest?

If there really is no permissible option for sealing and your main contractor refuses, you have to accept that for now. Because the groundwater level gets pretty high. What about the next 80 years? Weather phenomena tend to become more intense. I would also play it safe there.

On our 300 sqm plot, there's also a rather suboptimally placed outdoor unit, but that was still the "lesser evil" for us.

Tell us if there are any new insights?! Maybe you’ll get some good tips if you show a bird’s eye view of your floor plan of the basement and the property?! We also received great advice that we hadn’t thought of ourselves.

Since then, I haven’t had another appointment with the main contractor. In the last conversations, the indoor heat pump was clearly rejected if I insisted on it, without any guarantee. However, I also have a statement from a friend who is an architect and actually sees no problem with the indoor installation, it just has to be done "properly," but the main contractor doesn’t want to hear that.

That’s what the situation looks like. For me, the only sensible place for the outdoor heat pump is next to the garage driveway, which is also as far away as possible.

I am now looking for an expert for construction supervision; let’s see what he says about the topic...

You have "flooding problems" and are building a staircase into the basement? Then the thing with the [Weiße Wanne] is pointless. And the [GU] has no problems with that? I don’t understand anything anymore.

I have taken a look at the floor plan. is absolutely right about the stairs to the basement. On the "www" you will also find discussions about how susceptible a basement staircase is when it comes to sealing.

Next are the two light wells with a parapet height of 1.02 m – I also see this very critically. Among other things, waterproof windows need to be installed here (if they even exist/are permissible in this size). By now, I no longer understand your general contractor when he says he does not guarantee the air ducts but has no problem with the basement stairs and the light wells.

We also have a light well and precisely because of the risk of groundwater, we set the parapet height to 1.45 m (or even higher) – especially since there was no approved waterproof window in the required size.

Since we now have leaks in the basement despite WU construction, I strongly advise you to consult a specialist planner or expert and develop a sealing concept for your basement. I regret not having done that! Furthermore, it is strongly recommended to have the basement construction externally monitored. We did not implement this either (we convinced ourselves that the construction engineers and architects in our circle of friends would take a look if necessary, but it never worked out time-wise).

All possible influencing factors and conditions must be checked in advance in a sealing concept. It is commendable that you have already had a soil survey done; this is the basic prerequisite for the following concept.

After having seen your floor plan, the air duct is your smallest problem and I speak here from my own very recent and painful experience.

*EDIT:
Could you please explain exactly how the basement is being built? Formwork or element walls? Thickness? Which concrete is planned? How will the sealing between the floor slab and the wall be done? Pentaflex or hoses for injection?
Do you possibly have an excerpt from your construction description? I repeat myself when I say that quite other things need to be clarified than blindly entrusting this to the general contractor – really, believe me...

Don't worry, the general contractor also had enough objections regarding the windows and the staircase. However, all of these could be resolved. The windows will be made with waterproof basement windows, of course not in the size as drawn (I don't have the revised plan yet). And there will be a waterproof roof on the basement staircase.

I don't have the construction description at hand right now. It will be shuttered, that's the only thing I know. Which concrete, etc., was not detailed to me. But I assume it will be fine. In this region, all basements must be waterproof, and it's a local provider. From previous projects, I am not aware of any problems there. The only issue is that we cannot reach a solution with the heat pump.