Hydraulic balancing air-water heat pump + efficiency circulation pump

So flow rates are limited, the pump still does whatever it wants...

Vaillant has also commented:

thank you very much for your inquiry.

As soon as the electronics detect that there is not sufficient volume flow in the system, no heating or hot water function will be performed.
Whether the achieved volume flow comes from one or from the entire heating circuit is irrelevant for the device electronics. The only thing that counts here is that
the volume flow is present in order to be able to start heating.

It is therefore often advisable to install a hydraulic separator, a heat exchanger, or even a buffer storage as hydraulic separation.
Best regards

Your

Vaillant Service Center

That only refers to the minimum volume flow.

If the temperatures and the consumption are right, it is still okay.

The issue with temperatures and consumption will still have to be seen.

The response from Vaillant is still brief and not very informative, as I explicitly asked how the system regulates whether based on flow temperatures, return temperatures, volume flow, and whether the system would only regulate cleanly with an ERR.

So a short update:

In the meantime, I have figured out the heating curve and temperature changes for us bzw our house:

Heating curve 0.10 with a base point increase of 1°C

Everywhere in the main rooms 20.5 or 21°C as desired

WC and utility room I can't get lower than 17-19°C without completely shutting down the circuits..
The same applies to the bedroom, where only a lot of ventilation in addition to the almost shut down circuit helps, so there is nothing more to get from the adjacent bathroom because otherwise it heats the bedroom too much.

The issue will hopefully be resolved eventually by the electric heater if you want it warmer temporarily.

Electricity consumption from yesterday morning to today morning at 1°C outside temperature was 12 kWh for heating and 2 kWh for hot water

The compressor runs almost 24h nonstop.

Today I hopefully still have a phone call with Vaillant about whether a possible night setback still makes sense; but for that I first have to learn more about the icing and defrosting of the Vaillant outdoor unit.

Well, that's great that things are going well now.