TGA planner difficulties, underfloor heating supply temperature + wastewater ventilation

However, the planner has so far followed a working method that simplifies his work rather than prioritizing the comfort of the user.

We have a new building here (end-terrace house, KFW 55, ETICS, no large window areas) and I am told that the technically minimal possible flow temperature for underfloor heating on the ground and upper floors and air-water heat pump is 40 degrees.

Under the following conditions, a lead time of 40 can be realistic (even with KFW40):
-no electric towel radiators
-parquet or carpet as floor covering
-no unheated attic in the top floor present
-temperature gradient greater than 4 Kelvin
-not all rooms of the building are heated + high thermal conductivity of the interior components (interior walls and ceilings)

Thanks for the information.

Our situation:
- electric towel warmers available
- possibly designed for parquet flooring, but it should not be
- no attic (flat roof)
- temperature difference is currently unknown to me
- all rooms heated (except hallway)
- interior components made of sand-lime brick or drywall

We have a new building here (end-terrace house, KfW 55, ETICS, no large window areas) and I am being told that the technically minimally possible flow temperature for underfloor heating on the ground floor and first floor with an air-to-water heat pump is 40 degrees

Who on earth is talking this nonsense? Are you mixing up min. with max.? Please first request the documents/heating load calculation (if that's even possible).

So far, I have not received any documents, but at least the statement that a new planning status with more details is expected by mid-August. However, it seemed more like not much has been planned yet, but simply numbers thrown out there to say something. When asked specific questions, the reaction is rather confused and it is said that this has to be checked again in the documents. At least I have the assurance that I can view the documents. I will also ask my building surveyor again if he will look at it with me. Maybe that will help the planners work a bit better.

Again, regarding the underfloor heating. The only binding statement I have received is that the current installation spacing in the living rooms is 10 cm. But even that does not fit in any way with the other boundary parameters.

Regarding the second point of the wastewater ventilation, I have at least received the documents (so they have apparently dealt with this). Unfortunately, it is understandable to me. The row houses are staggered relative to each other, and if I want to run roof penetrations behind the shower wall, it is too close to the parapet. Specifically (see picture): S15 and S16d must have sufficient distance from each other and the distance to the parapet must also be maintained.

So, I have finally received further information again. According to the TGA planner, it looks as follows:

- The bathroom is now planned with a 5cm laying distance, however, the flow temperature must be at 40°C to reach the target temperature of 24°C in the bathroom. (Small area due to bathtub/shower etc.)
- Since the flow temperature is at 40°C, a laying distance of 20cm will be chosen in most other rooms.

I am just a layman but somehow this does not sit well with me. My proposal now was as follows:
- Keep the laying distance in the bathroom at 5cm, if possible add some wall area (let’s see what is possible) and lower the target temperature in the calculation to 22/23°C.
- This should reduce the flow temperature and thus the laying distance in the rest of the house should also be smaller (20°C design in living rooms).

Ultimately, it is the calculation parameter that changes, but this allows for a smaller laying distance in the rest of the house. There is an additional electric heater in the bathroom. Does this make sense or am I just deceiving myself because in the end I will have to raise the flow temperature again (for the bathroom) and throttle the flow in the rest of the house?

If I am to believe all this, I should receive documents for the heating load calculation (room by room) next week. The heating circuit lengths should be between 70-90m.