Hot Water
Hot water is created for your apartment via a ground-source heat pump. We have been told to leave all the controls alone.
The big tank in your utility cupboard stores the hot water. It has its own control panel and can also be controlled from the living area, but to a limited extent.
Daikin Altherma 3 WS Operation Manual
I have also found: Daikin Altherma Heat Pumps handbook
There is the device on the wall that controls the system :
Daikin call this control a 'Human Comfort Interface'.
However, if it develops a fault then the light will flash red and show an exclamation mark within a triangle, like below, not only on the room display but also the tank in your utility cupboard will also flash red and show a red warning triangle:
To fix this, open the electrical circuit-breaker cabinet and turn off the breaker marked “Central heating”, then after a few seconds turn it on again. We have found that you will have hot water again, from a cold tank to full heat in about 1 hour.
Human Comfort Interface - Installation and Operation Manual
Human Comfort Interface - User Reference Guide
Heating and Cooling
Warm and cool air is distributed to rooms via a ventilation system (a Daikin Altherma heat pump convector) in the ceiling and its associated controller :
How to swap from heating to cooling ←– New 
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How to swap from cooling to heating ←– New !!!
You should have a manual within your apartment but here is the online version :
All you need from this manual are pages 10, 11, 12 and 13.
The - and + keys lower or raise the temperature. That's the easy bit.
The snowflake symbol: press once and it will show a blue icon if it is in cooling mode or a sun icon if it is in heating mode.
Press and hold the button to change the mode from heating to cooling. You might hear a relay click up in the ceiling vent area.
AUTO provides heating or cooling, whatever is required to get to the temperature you have set. This AUTO mode might be all you need.
The Moon and Stars button - Night mode - under investigation.
The single fan button is low speed fan, i.e. quiet mode, the double fan button gives a bit more oomph but might be more audible.
If you get any error codes on your unit you can find out what they mean: daikin-error-codes.pdf