Cabinet with air-water heat pump, water storage.. Does anyone know it?

Why do ventilation and heating have to be separate?

Technically, there is no reason to combine controlled residential ventilation and (water-bearing!) heat pumps: the controlled residential ventilation already uses the waste heat of the house, which in any case would not be sufficient for the heat pump. In case of replacement and maintenance, you are tied to ONE outrageously expensive exotic device from one or a few manufacturers. Why should anyone do that? You replace controlled residential ventilation for 3k€. Water-bearing air-water heat pumps start as a monoblock also at around 3k€, the hot water storage can be separate. Split heat pumps with integrated potable water storage are, of course, more expensive. It is rare for everything to break down at the same time. The development of the devices continues, and in the case of replacement, you want to have free choice on the open market. Unsuitable combination devices are apparently often used by some general contractors in practice; taken to the extreme, these are pure air heaters. In forums, homeowners show up after a few years wondering about the enormous electricity bills, as they are largely heating directly with electricity despite expensive heating. Combination devices are for me initially an indicator that things will go wrong. Ideally, with good planning, you come close to the consumption of a good separate heat pump regarding operating consumption.

but, just give him a call, he should name the manufacturer and model designation, then we can see further.

And also the transmission heat loss of the house, as well as the heating load.

As far as ventilation is concerned, we are open, as far as I'm concerned it could also do without, I have no problem with airing..

Then just leave it out. Central controlled residential ventilation costs from about €10k and is pure comfort.

Could Stiebel Eltron LWZ 604 Air or Tecalor TCO 2.5 be meant.

Combination units for hot water, controlled indoor ventilation, and heating with inverter air-water heat pump.

It is a hybrid. On one end there is an air-water heat pump with refrigerant circuit, compressor like the LWZ 504, so the disadvantages of a pure air heat pump are eliminated. On the other end, no underfloor heating is connected, but the ventilation.

I believe it has been on the market since autumn 2018. In 2017, it was intended for passive houses. In winter, I heard that it is also installed in somewhat less well-insulated houses.

The warm air is 'distributed' by the ventilation system, the complete cabinet costs about 20K € and is very low-maintenance.

To me, that sounds fantastic. We could install our desired wooden floor without underfloor heating, save a lot of money, and expect less maintenance.

You actually can't build much worse for heating, except for supply temperature. You have a real passive house.
Why can you save a lot of money with 20k€? Why did you want to do without underfloor heating?
Underfloor heating is actually always the best solution, and you are not tied to any producer.

Many thanks for your answers!!

you are great exactly this is the device the advisor was talking about.

I know very little about heating and technology, which is why I asked this question.
The summary is therefore that water, as usual, is best suited as a heat storage medium.
Only if it is a real passive house that has only minimal and localized heating needs could this hybrid be worthwhile: it heats up quickly, but would also dissipate quickly.
Did I get it right?

Underfloor heating
I love thick wooden floors. Of course, they can also be combined with underfloor heating, but the heat conduction is miserable.

As an alternative, I only know wall heating (with clay I would find it perfect), but it is considerably more expensive than underfloor heating. That's why I thought this "cabinet concept" could be interesting.

Only if it is a proper passive house, which has only minimal and localized heating needs, could this hybrid be worthwhile: it heats up quickly, but would also dissipate quickly again. Am I right?

Essentially correct. You cannot heat up quickly with a heat pump. Ideally, it runs continuously at low/appropriate output and is not oversized. The problem with air heating is that, unlike water, air transfers little heat. To warm up a normally insulated house, the air temperature would have to be raised so much that the efficiency of the heat pump drops significantly. The problem with pure exhaust air heat pumps is that the energy from the exhaust air is not sufficient to heat the house. As a result, an electric heating element is switched on. Unfortunately, it can be so inefficient that you might as well have heated directly with electricity. From the manufacturer of the device mentioned, I get the impression that planning is usually reasonable and you won’t completely fail. Nevertheless, I would clearly prefer a conventional solution.