Wall heaters do not reach the desired temperature

Hello everyone,

I need your help. We have the problem that we unfortunately cannot get our bathroom properly 'warm'. Due to the small underfloor heating area of the bathroom, 3 additional wall heaters were installed. Nevertheless, we cannot get the temperature above ~21 degrees. For the calculation, 24 degrees were used. I have already turned off EER and set the flow rate to max (3l/min). All other rooms easily reach their target temperature and some are already at the minimum flow rate.
Do you have any other idea what could be done?

Many thanks and best regards

Is this a new building?
How big is the bathroom?
What kind of heating do you have?
What do you mean by „Wandheizungen“?
What is it like in the other rooms?

Additionally:

Was there a hydraulic balancing?
What is the supply/return temperature at what outside temperature currently?
Installation distances?

That the bathroom is the problem room is not unusual. However, if it was actually designed / calculated that way, it should not be like that… actually

Yes, it is a new building. We built according to the Energy Saving Ordinance in 2020. The bathroom is just under 10 sqm. The house has complete underfloor heating and uses an IDM iPump ALM 2-8 as heating. By wall heaters I mean that additional pipes have been installed on the wall with a separate heating circuit. The other rooms, as mentioned, are all warm and rather tend to be too warm. For example, the living room is a good 23 degrees even though I have already reduced the flow.

Additionally:

Was there a hydraulic balancing?
What temperature supply/return at which outside temperature currently?
Installation spacing?

That the bathroom is the problem room is not unusual. However, if it was actually designed/calculated that way, it actually shouldn’t be... actually

Hydraulic balancing was done according to the heating engineer. I’m not sure about the installation spacing right now but I think 10cm. Supply is currently 29.4 at 1 degree outside temperature.

Edit: Unfortunately, the return cannot be read. It doesn’t necessarily have to be 24 degrees but 23 would be nice.

Wall heating extra heating circuit? If yes, what flow rate do they have? What heating circuit lengths? Did you get an exact design? 15cm in the bathroom? That would be quite a large spacing. Was it laid with the same spacing throughout the house? Where was the flow measured? What rooms border the bathroom? Bedroom? What temperatures are there? I am also just an amateur with a little bit of self-taught knowledge, sorry for the many questions but the more info the more one can at least guess.