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
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