I've been moaning for years, since I installed it, that my Vaillant 470F control system, seemed to store a temporary change in the programmed temperature, as the programmed temperature. It's seems I was wrong, that I was deceived by the display's sometimes excessively long time to update itself....
The display is battery powered and wireless. The display is blank, unless woken up by twiddling the knob, or the buttons. Twirl the knob, it wakes the display, which then shows what it last displayed, but usually quickly updated. If the last thing it showed, was you having tweaked the temperature up a little, it will still show that temperature as the 'desired temperature'. Sometimes, the display would awake, with the last 'desired temperature' setting visible, which it would show until the display went to sleep again, only if you wake the display a second time, do it show the true 'desired temperature'.
The display is battery powered and wireless. The display is blank, unless woken up by twiddling the knob, or the buttons. Twirl the knob, it wakes the display, which then shows what it last displayed, but usually quickly updated. If the last thing it showed, was you having tweaked the temperature up a little, it will still show that temperature as the 'desired temperature'. Sometimes, the display would awake, with the last 'desired temperature' setting visible, which it would show until the display went to sleep again, only if you wake the display a second time, do it show the true 'desired temperature'.