ᐅ Underfloor heating in the children's room? Some rooms planned without underfloor heating? Removing the air-to-water heat pump?

Hello everyone,

I'll briefly introduce the topic:
We are planning a two-story single-family house of about 180 sqm (1,940 sq ft) with a basement, built with Poroton 42cm (16.5 inches) bricks and as much photovoltaic system as possible on the roof. Since we want to insulate well not only with the bricks but also with the windows, the base slab, the basement, etc., we are considering an air-to-water heat pump (following the motto "a well-insulated house doesn’t need a huge heating system").

Now we are wondering whether we should install underfloor heating in the bedroom or children’s rooms at all, because it is said to be slow to react and can cause uncomfortable temperatures in summer, which again leads to poor sleep. Also, different temperatures are needed in sleeping areas than in living areas. Of course, children’s rooms are tricky since they are used for both activities in the afternoon and for sleeping at night.

We want to install underfloor heating in the kitchen/dining area, living room, and of course the bathroom. Can you plan for two different supply temperatures for the underfloor heating (one warmer for kitchen/dining, living room, bathroom, study and one cooler for bedrooms and kids’ rooms)? What about rooms like the hobby room or guest room? My wife often makes wreaths or works on crafts in the hobby room, so it definitely does not need to be as warm as the living room. The guest room we would not want to heat throughout the entire heating season, but only when guests are actually staying.

However, I read that underfloor heating works best when water is circulated continuously? What is recommended for guest rooms or hobby rooms? The quickest way to heat them would probably be with conventional radiators rather than underfloor heating? But what I have read so far suggests that air-to-water heat pumps may not be ideal for that. Should we consider a gas boiler instead (connection available on the property)? Or is it possible to operate underfloor heating with an air-to-water heat pump with different supply temperature circuits (1) living areas 2) sleeping areas 3) rooms heated only as needed)?

This sentence made me doubt:

"To ensure optimal operation of the heat pump, underfloor heating should not have individual room control installed."

(Source: Bundesverband Flächenheizung e.V.)

I understand this to mean that the whole house should be heated with one supply temperature, ideally all through underfloor heating. Of course, with multiple circuits since each circuit should not exceed 80/100 meters (260/330 feet) in length (pressure loss, etc.). But all with the same supply temperature, otherwise that would be individual room control again, which should not be installed.

I hope you can shed some light on this.

Underfloor heating is very important to my wife, so we won’t avoid it. The question is what we do with the hobby room, which needs much less heating (or also the bedrooms and kids’ rooms?), and the guest room, which is heated much less often. Is that even possible with underfloor heating and an air-to-water heat pump?

Have a great evening and enjoy the upcoming pre-Christmas season.

I’m really impressed by the many helpful people here who support future homeowners like me, who don’t just go to a general contractor and say “Do it and give me the keys sometime, I don’t care about the details,” but who want to dive into all the different trades involved. At the same time, it can be overwhelming and confusing due to the huge amount of information available online, especially with little prior experience.