Air-to-air vs. air-to-water heat pump KFW55 house - cooling function important

If you’re always going around in slippers anyway, then where’s the problem? If in doubt, just visit a place like that once. We just had visitors over the weekend and, as always, they were absolutely thrilled with the cooling.

If possible, I would like to avoid it in summer. But if the opportunity arises, we will certainly test it ourselves.

Yes, strangely a cold floor all year round is very stylish and cool in old buildings, etc.

Maybe for others, but not for us.

Just saying: What do you actually think the tiled floor feels like in winter with an air-to-air heat pump? THEN you really have a problem. With underfloor heating the floor feels foot-warm. With an air-to-air heat pump it’s just cold – obviously, it has to be much colder since it’s not heated. It has to be at least a real wood floor so that not everyone (not just you) has such cold feet.

Thanks for the hint. We were already aware of that; anyway, we would install real wood floors in most rooms instead of tiles (for aesthetic reasons and because of the heat issue). But yes, in winter, there are many arguments for underfloor heating. We were more concerned about the cooling in summer. The consensus here seems quite clear in favor of an air-to-water heat pump, either with cooling function in the underfloor heating or with air conditioning.

Thanks in any case for all the replies, that helps us in making our decision!

Greetings from the post of the

Fundamental decision between air-to-air heat pump and air-to-water heat pump

Have you planned a central ventilation system?
For us, it is now tending towards an air-to-water heat pump with central ventilation (still uncertain whether with cooling function) and photovoltaics.

Also, I would definitely install a proper air conditioning system immediately.

You say that so easily, if we had unlimited money available, we would have gone straight for photovoltaics + air conditioning. However, the cooling function of the heat pump only costs about 500€ extra, so that would be the only option at first. I will replace the thermostats anyway in the long run, since I want to install the smart thermostats from our current apartment. Unfortunately, the general contractor is somewhat resistant to not installing and deducting the other thermostats at all, because they have had bad experiences in the past with thermostats procured by the builder (drying of screed delayed, thermostats defective, etc.). They would prefer to have everything under their own responsibility before we do the final inspection. That is understandable to me, and I can accept it for now. Since I work in IT myself and would probably call myself a nerd, I plan to retrofit the entire house automation myself over the next few years anyway. We were not willing to spend the money upfront, and I enjoy something like that anyway. It has become a small hobby by now, I would say.

The cooling function of the heat pump, on the other hand, costs only about €500 extra

Where do the costs of €500 come from?

Where do the costs of 500€ come from?

To be honest, I found them here in the forum from a somewhat older thread when I dealt with the topic at the beginning of the year. You would probably need some kind of extra valve and humidity sensor, etc. The conversation with our plumber is still pending. It's on my to-do list for next week.

For me, cooling via underfloor heating is neither fish nor fowl. We dealt with it intensively before Building 1 because we also wanted to use synergies. But most sources say that you cannot exceed a cooling capacity of 2-3°C with it. Our situation is somewhat special because of home office - but in summer with 2 running computers and 4 monitors, we quickly get >30°C in the office without cooling. The rest of the house also heats up strongly through the window areas despite good insulation. You often read the opinion here that you have to consistently close all the shutters in summer. To some extent, I agree with that - without shading, it barely works in new buildings. But really closing EVERYTHING, all summer? Then you sit like a hobbit in the cave. For me, living quality looks different. In the end, we combined underfloor heating, air-water heat pump, central ventilation system, and a proper air conditioning unit. We gave up on the cooling function of the underfloor heating.