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.

Underfloor heating everywhere, unless you are planning a passive house. The heating is off anyway during the summer.

Lol sorry, but with 180m² (1,940 sq ft) and a basement, I wouldn’t skimp on underfloor heating. Install underfloor heating everywhere, including in the children’s room as well as the hobby and guest rooms. Air-to-water heat pumps basically don’t work well with radiators. In the bathroom, you can equip the radiators (towel warmers) with electric heating elements if you’re unsure. Individual room controls are required by energy-saving regulations but don’t make much sense with a hydraulic balancing system and are practically unnecessary.

Others can explain the regulations regarding underfloor heating to you.

Modern houses are not designed for rooms to have large temperature differences.
Modern heating systems operate with low supply temperatures.
This is different from older houses where the heating is turned up fully, the room gets warm, and the radiator becomes very hot. In one room you could have a sauna effect, while in the next room it feels like living with penguins. That is no longer the case.
Heating systems maintain the desired temperature within the building envelope, which is why they respond slowly. They are not designed to raise the temperature in a room by 8 degrees quickly.
Underfloor heating is turned off during the summer.

Alright, then I will install the underfloor heating everywhere, but how do I regulate different temperatures? Nobody wants the living room temperature in the bedroom as well.

Is it possible to have separate supply temperature circuits with an air-to-water heat pump?

@haydee Yes, I am aware of these facts. That’s why the hobby room probably won’t cool down as much as in old houses, where the heating was off there for days. But we also don’t need to heat it every day like the living room. Especially since we require a lower temperature there than in the living/dining area (because of the wreaths and so on). The same applies to the bedrooms. I can’t sleep well at temperatures above 18/19°C (64/66°F) in the bedroom. How is it supposed to work if I go upstairs from the living room, where it is hopefully a bit warmer than 20°C (68°F), to the bedroom and the same underfloor heating runs at 21-22°C (70-72°F) there?

Plan underfloor heating based on a room-by-room heat load calculation to achieve the lowest possible supply temperature. Keep all circuits around 80 meters (260 feet), with a maximum of 100 meters (330 feet). Avoid very short circuits. Start early as soon as the floor plan is finalized. Specify the desired temperature for each room. In the main bathroom, also install underfloor heating in the walls.

This is almost the most important factor for the efficient operation of the heat pump, and mistakes cannot be corrected later. Expect to intervene multiple times and request revisions of the planning. Pay accordingly for the planning.

Cover all areas, including hallways, hobby rooms, secondary rooms, and tiled shower areas.