Central room temperature controller for ERR underfloor heating

You can even disconnect the actuators and thus don’t even have to worry about whether all [ERR] are fully turned on. It also saves the standby power of the actuators...

Who performs the hydraulic balancing if I consider the installer to be incompetent (at least in these matters)? When should it be done? After the first heating period?

It seems that fine-tuning is not really worthwhile for a professional, as the results of adjustments only become visible after 2-3 days. This means a professional would have to come by several times in a row for 5 minutes. So it's best to read up and do it yourself.

So you mean that I should set all thermostats permanently to the maximum temperature and set the target value for the individual rooms directly on the heat pump?

That's right, and if done, an existing bypass valve should also be closed immediately so that the entire volume flow goes through the underfloor heating and not a large part bypasses it directly into the return flow.

who will do the hydraulic balancing if I consider the installer incompetent (at least in these matters)? When should it be done? After the first heating period?

You will have to do it during the heating period.

So you mean that I should turn all thermostats permanently to maximum temperature and set the target value for the individual rooms directly on the heat pump?

Sort of. You cannot set the target temperature of individual rooms on the heat pump. (There are systems with regulation, but that would again be an ERR).

You regulate the temperatures of the individual rooms with balancing. Use the "worst" room as a benchmark. You turn all valves fully open. Then you adjust the flow temperature so that your target temperature is reached in the worst room. Then the others should be too warm. You then close those valves step by step until they also have the correct temperature.

Of course, this does not work in 5 minutes.

It’s greatly simplified, but if you google it, you’ll find instructions.