Noticeable cooling effect in air-to-water heat pump

Upper floor / ceiling, preferably air space/stairwell

I always thought you need at least one device per floor. They usually only manage to cool a maximum of 30 m2, right?

Every house is different and accordingly, there is no universal recipe. There are many factors to consider and a lot to keep in mind. But open floor plans and open doors are helpful.

Every closed door is a natural obstacle and if you want to cool there as well, it either has to be open or there must be another indoor unit or the warm air has to be moved away from there somehow and cold air brought back in.

Adequately sized systems (assuming an open concept and open doors) can also be installed on each floor or even just one per house to actively cool the entire structure. Of course, the room where the indoor unit is located will be the coldest, with decreasing intensity the more obstacles there are on the way to all other rooms. Naturally, the size of the houses plays a role. I am referring now to the usual 120-180 sqm nowadays.

Since modern houses are well insulated, less power is needed for cooling and thus smaller systems can achieve what used to require twice as much power. For this reason, the so-called evil air conditioner is not as bad as its reputation.

Hm does it really work that well or what kind of effect is realistic? Structurally, we could relatively easily position an indoor unit in the upper floor hallway and connect it to the flat roof via an existing roof penetration in an adjacent room, where the outdoor unit could be positioned (power/KNX/network is available on the roof).

Is the hallway then freezing cold so that the cooling effect is noticeable in the adjacent rooms (even on the ground floor)?

Which manufacturers/products integrate well into KNX? :)

I used to have several indoor units. But at some point, I didn’t like it anymore. So a large 7 kW system was simply installed in the house with one indoor unit in the stairwell. I am currently sitting downstairs in the living room in the south corner on the sofa and feel a very slight cool breeze. Outside, it has been 35°C for a few days.

The system is running and is located one floor above. In between is a concrete ceiling with only the stairwell opening.

The system cools the whole house relatively quickly in 2-3 hours and maintains comfortable temperatures, or you only turn on the system when needed.

Additional electricity costs per season are 200-250€. But for that, you always have comfortable temperatures.

Daikin, Mitsubishi, LG, Panasonic, Toshiba, Fujitsu, and all kinds of other manufacturers have a direct KNX gateway. Daikin is my choice.

We have been using this cooling function of the air-water heat pump for the third summer now. It was simply included. If you program it sensibly (start already at 24 degrees AT and of course usually leave the blinds on the south side on "slit" during the day), it works wonderfully. The entire family envies us how pleasantly tempered (not cold!) the whole house is. Room temperatures downstairs and upstairs (open design) about 23 degrees. We like it that way. Electricity costs are negligible thanks to photovoltaics. However, here in the area (altitude > 700 m) we also always have about 5 degrees less than in the lowlands as well as fairly cooled nights. It is somehow always a question of the overall conditions; for us here, a "real" air conditioning system would certainly have been too much effort.