Alternative to Weishaupt WWP LS 8 (Rotex, Kermi, ...)?

Sounds like you are already not doing too badly.

Try posting your house with the heating load calculation(s) in the pink htd forum, you’ll get more expert information there.

Not assessable without plans, but the heating load is very high, especially since planning includes a ventilation system. The heating load often contains too many safety margins (search for crinks Tool). Depending on the architecture, BKA might make sense to further lower the supply temperature.

Personally, I would try to avoid buying an expensive air-to-water heat pump from the heating engineer (they don’t last forever, you buy it twice like any heating system) and rather take another look at/check the house concept and reduce the heating load or plan with a trench collector, especially if you live in a colder region I would consider air as a source not optimal.

Thanks, it's also not that easy to get a good overview here.

The heating engineer also calculated with a maximum of 6kW, but according to the information from the Energy Saving Ordinance and the heating load calculation, I come to 7.6kW. I think that 6-8kW should be fine. As long as the air-water heat pump modulates, it shouldn't be too bad if I take 8kW. Of course, I have to be careful that at low temperatures the necessary heating load is not too low and possibly falls below the modulation limit.

We once considered [BKA], but dismissed it. I'm also thinking about buying the air-water heat pump myself and possibly having it installed by an acquaintance (heating engineer). I find the prices a bit outrageous.

If the heat pump modulates well, I don’t see oversizing as critical either.

In our Energy Saving Ordinance it also said 7.x kW. The heating installer said 6 kW. Room-specific heating load according to DIN: 4 kW, in reality with hot water it is 3 kW. Try roughly calculating it yourself based on the U-values and surface area, it’s not that difficult and it helps with understanding.

For self-installation, the 5 kW Panasonic is suitable, also because there are many tips and plans available online. If a trench collector is not an option and you want to stick with an air-to-water heat pump, then I would really try to fit the Panasonic. For emergencies, there is also a 3 kW heating element on board. It is a lot of money that you can save in the long run if you plan well and don’t just let the heating installer do whatever they want.

I just noticed, you were the one with the cool floor plan. Through the roofs and windows, the heating load can be a bit higher, but it doesn't have to be. It's best to calculate it yourself. Be sure to plan the windows with warm edge spacers. Ring trench collector is not an option?

Thanks for the tips! How did you calculate the room-by-room heating load? I wouldn't install it myself, but rather get someone who is an expert to help and assist him. It shouldn't be a bigger problem then, for example if you can also set up the Panasonic on your own. I once considered a ring trench collector, but the plot is relatively small and even if we have to build up (70cm), we first have to build up and then dig the trenches again. Our plot is also not huge at 16*28. Thanks regarding the floor plan. It has turned out to have a few pitfalls. The utility room is a bit small for the air-water heat pump, photovoltaics + storage, and KNX. The children's bathroom upstairs is a bit too small because the walls here are load-bearing and the architect did not take this into account. As a result, the shower was a bit tight, but we reduced the size of the window and therefore it fits again.

The tool is good for a rough estimate and sufficient for sizing the heat pump. You can also safely omit the hot water surcharges; it certainly won’t get too cold.

I had the room-by-room heating load calculated; a heating engineer can do this, and there are also online service providers—it’s not expensive. Based on this, the underfloor heating is planned; you should check this yourself.

Great if you have someone who is a professional and can help you with the heat pump.