Is the heating oversized?

It has been written several times: Open all ERR fully to maximum and try to bring your place to a tolerable temperature using the heating curve and flow temperature setpoint. As long as the ERR regulate themselves, it won’t work. It is clear, however, that the heating is really at the upper end of its capacity. In a 2005 "Altbau" of the same size, we have an 8.5 kW heat pump. That is more than enough....

It has been written several times already: Set all ERR to Max and try to bring your place to a tolerable temperature using the heating curve and flow temperature setpoint. As long as the ERR are regulating themselves, it won't work. However, it is clear that the heating is really at the upper limit of its capacity. We have an 8.5 kW heat pump in a 2005 "old building" of the same size. That's more than enough....

I have done that for now... All controllers set to - and the flow rate at the HKV initially set to 1 liter per minute... Reduced the design temperature (at -15 degrees) from 45 to 35 degrees... now I am waiting to see how the heat develops... If rooms are too cold, the flow rate will be increased; if too warm, decreased.... let's see how the boiler's behavior changes now...

Direct heating curve settings don't seem to exist with Junkers..?

Despite 11 open heating circuits (i.e. 11 liters/min flow), the boiler only heats for about 5 minutes at a time and then switches off again... and then turns on again after a few minutes... the starting temperature is now about 23 degrees and it heats up to about 32 degrees... so adjusting the design temperature has already had some effect... but inside the building it is currently only about 18 degrees... so still too cold... then I will probably have to increase the flow a little more...???

The pressure is currently just over 1 bar... could this also be related? It should be around 1.5 bar, right? The heating company will come again tomorrow/the day after tomorrow... or does this not make much difference yet?

I have fully turned up the flow of the warmest rooms (bathrooms, living room, kitchen) and then adjusted the heating curve accordingly.

Heizkurveneinstellungen direkt, scheint es bei Junkers nicht zu geben..?

In another forum, I read that the Junkers Cerapur has a base point and an end point. The base point is the flow temperature required at 20 °C outside temperature to heat the apartment. The end point is the flow temperature required at -15 °C outside temperature to heat the apartment.

If you move both points up or down, you shift the curve parallel. If you move only one point up or down, you change the slope.

I have turned the flow rate of the warmest rooms (bathrooms, living room, kitchen) fully up and then adjusted the heating curve accordingly.

I have done that now too... I am now at 17 liters flow... unfortunately, I can only observe in the evening how long the heating times are now...

What does the boiler actually modulate on? In other words, which parameter tells it to run at lower output? In my case, does it make sense to throttle the max heating output... according to the default setting, it was:

Min. heating output: 36%
Max. heating output: 84% (now I have 50%)

Would it therefore make sense to set Min (36%) = Max heating output (36%)? That would still be 7.3 kW...

Sorry, I have no idea.