Building services for a new city villa 230 sqm

Well, you can hardly find companies that want to do good work... just ask the manufacturer if they absolutely require it, then you'll definitely know who you can trust more.

Hello, today I inquired about the buffer and it is absolutely necessary. Regardless of the manufacturer, I have 5 offers from 4 different manufacturers and all include a buffer, it always costs about 500,- euros net. It is necessary for the operation of the heat pump so that it does not go straight to 0 from full operation. It’s like a car that doesn’t brake before the wall but drives straight into it. The heat pump also runs without it but there is risk and a much shorter service life. It is not the wish of the heating system installers but a requirement from the manufacturers.

Hit me, but how can you afford such a house if you write so unsorted? Or else: What am I doing wrong?

Great post - what does one have to do with the other?

Besides, it's easy to read, isn't it..?

Actually, you have to leave such answers without words.....

, you are right, I'm also thinking about whether to do it that way but we still want to go on vacation twice a year with our kids, continue to drive our T5 Multivan and the S Max as a second car, additionally the 2 BMW motorcycles need to be maintained, the hobbies of the 4 girls, dancing, riding, piano.... You have to make compromises on the house and it will just be a bit smaller...

But to the point, manufacturer’s statement:
With a buffer tank, the primary question is: Are the heating circuits controlled? You can directly connect to the underfloor heating if no more than 20% (bedrooms) are controlled. Since underfloor heating is a very slow-responding system, in new buildings you can easily endure the lockout times without the room temperature noticeably changing. If the heating circuits are controlled, it is essential to install a buffer tank in the size range of 30-50l / kW heating capacity.

If no heating buffer is present and the heating curve of the heat pump is set higher than that of the room control, the spread of the heat pump between flow and return can be over 30 degrees, which in the worst case can lead to a high-pressure fault. With a buffer tank, the heat pump has a constant temperature difference between flow and return temperature of 5 degrees, which represents an optimal operating point of the refrigeration circuit.

And

With underfloor heating, a buffer tank is only necessary if 100-percent individual room control is installed. This is required by the [EnEV]. “Clever” heat pump installers dispense with this 100-percent individual room control by allowing some (few) heating circuits to flow continuously. This then means that the room temperature is controlled, for example, in only 50 percent of the heating circuits. For air-source heat pumps, it must also be considered that without a buffer tank, the defrosting capacity (e.g., during defrost operation by refrigeration circuit reversal) must be withdrawn from the underfloor heating.

Ideal is the use of a modulating heat pump that adjusts the output to the necessary demand via the outside temperature, including for defrost operation. This means that dispensing with a buffer tank requires an installer who can assess the situation. Systems without a buffer simply require somewhat more experience with heat pumps.

Dispensing with the tank can lead to higher efficiency if done correctly.

You should make clear that the text is not written by you.

By the way, individual room control is really nonsense - I refrain from it. As well as the buffer storage.

Modulating heat pump? I think that doesn't exist for brine... but I'm currently unsure.