so in summer you then suck the warm air from outside into the house, don’t you?
Yes, but even here the function of the controlled residential ventilation hardly matters. Because what a controlled residential ventilation achieves in this area is negligible. The controlled residential ventilation is not suitable for cooling or heating, but very good for air exchange. Simple as that.
During the day in summer, the controlled residential ventilation usually runs at minimum ventilation, which is about 70 m³/h in our case, whereas the air-to-air heat pump circulates 700 m³/h at the lowest setting. So ten times the amount.
About one cubic meter of warm air enters the house per minute, but about 10 cubic meters are circulated and tempered.
The controlled residential ventilation is really the least problem in summer.
If controlled residential ventilation and air-to-air heat pump are separate, do you then have separate air intakes and outlets in every room?
No, we have an open concept and practically the entire ground floor is open designed and all doors upstairs are always open.
So the cooling of the air-to-air heat pump is not used via the underfloor heating if I understood correctly, since it also does not bring much, but also not via the controlled residential ventilation.
Yes, because both bring little since they are not designed for that purpose and only represent a side effect.
The cooling must take place in the upper areas of the rooms because heat accumulates here, it brings little to no use to cool the floor (which is why cooling ceilings are sensible and efficient) and the controlled residential ventilation is simply too weak even at the highest setting to circulate the necessary air volumes.
This implementation would already mean a very high purchase price, since you basically buy two systems instead of one.
The heating concept must be created individually for each house. What works for you does not necessarily have to work the same for your neighbor. For every task there is the appropriate solution.
However, gas boilers (to return to the initial question) are still the number one heating source in single-family homes and will most likely remain so for some time. Because the technology is mature and with comparable operating costs of a heat pump you can heat the house but need only about half the investment capital. Here one could go further and include the interest rates.
It is also always interesting to read that everyone knows about the function, costs, and problems of an air conditioning system and immediately rejects it with the phrase: "No thanks, way too expensive and unreliable." But when it comes to a heat pump for heating, people do consider it or install one without thinking.
Over all these years here in the forum and out there, I still had to notice that active cooling for retrofitting gains more and more popularity, because the replacement measures (shading etc.) are not sufficient and the tight and well-insulated houses simply become too warm in summer.