Wall heaters do not reach the desired temperature

What is then the hydraulic balancing? Where can I check it?

Hydraulic balancing is the rough setting. Thermal balancing is then the fine-tuning of the system specially adjusted to you as an occupant. The heating engineer simply cannot know all your preferences beforehand, so he cannot set everything 100%. He does 90%, the remaining 10% you have to do (or you commission someone). With hydraulic balancing you compensate that heating circuits of different lengths build up different resistances and are supplied differently. Short circuits would otherwise be flowing more strongly due to the lower resistance; of course, the heating water gives off less heat over the short length and returns with a return temperature only slightly lower than the supply temperature. This reduces the overall temperature spread. This is especially problematic with non-modulating heat pumps and return-flow-controlled heat pumps—keyword "short cycling". With a perfect hydraulic balancing, the longest circuits are fully open and the shorter ones throttled so that all circuits have a very similar return temperature. The calculation of the hydraulic balancing simultaneously includes the thermal balancing because you include certain target temperatures in the rooms in the calculation. However, many errors obviously almost inevitably enter the calculation. Hydraulic balancing only ensures that each circuit is supplied accordingly (after all, there could be several circuits in one room, of which one part is undersupplied and the other oversupplied). The calculation results provide the basic setting for the individual circuits—it is obvious that there are some inaccuracies and that some fine-tuning has to be done here and there. The entire procedure is already quite time-consuming. If you change the flow rates more than just slightly, you have to wait and measure for 2-3 days until the change shows its full effect. Meanwhile, there should not be any major solar gains (even in other rooms) to avoid distortions, otherwise it takes even longer. If the whole process can be significantly shortened by a few preliminary calculations (hydraulic balancing), that is very helpful.

This is now a simplified representation, which, however, maps the basic function.

This is currently the best, very easy to understand explanation on the web. Thank you (even though this knowledge has no practical application in my house).


I understand it like this: Unfortunately, your heating is not well implemented or there is a defect. If it is already very warm in the house and the bathroom remains too cold even though the flow is set to “full blast,” you will only make the bathroom warmer if you increase the supply temperature and throttle the flow for all the other rooms. Somehow, that is a stupid, because inefficient, solution.
I would do the following:

[*]Report the system as "defective" to the heating engineer because the bathroom is not warm enough. Do not reveal background knowledge or express guesses. The result is: The bathroom is too cold. Please ensure that the bathroom gets warm.
[*]Prepare myself for the possibility that there is no defect and no good solution (without accepting that too quickly towards the heating engineer—the engineer should come up with something).
[*]Set a priority whether I want to run the entire heating system less efficiently or integrate an additional heat source into the bathroom despite careful consideration beforehand or deal with the lower temperatures.
[*]I would be reluctant to pay in full for a wrongly dimensioned heating system. That would require further discussion—and if the heating engineer covers the additional heating with a nice design. (We have an Eve from Tubes, which we can control temporally to locally produce a few extra degrees. It produces nice light, looks nice, but is not very quiet. It is not used often, sometimes in the bathroom.)

Yeah, so the thing with the straws doesn’t sound so great at first. The heat output isn’t that optimal. Do you have data on the wall elements? Length, diameter, maybe even a room-specific heating load calculation that shows how much power they are supposed to deliver? The concern would be that the tubes don’t deliver enough power. But then it would be a design/planning error if the bathroom was commissioned for 24 degrees. So I’m with on this: if nothing obvious is going wrong, then the heating engineer is the contact person.

super thank you very much I understood that.



Unfortunately, this is the only thing I found about the wall heating elements.


Yes, the flow temperature would still be an option, but I would prefer not to increase it. It feels like it could rather be decreased and the flow rate increased. The other rooms are all fine.

Ok so you also think that something must be wrong and I should contact the heating engineer. Then I would first reset everything and write to the heating engineer?

Maybe the pass cylinder is swapped?

Maybe the pass-through cylinder is swapped?

Interesting idea. Then I'll close the bath circuit and see what happens.