If you open a window so that the temperature at the HR 40 drops sharply for
more than 3 minutes, the HR 40 closes the radiator valve in order to save
energy. The display then shows the message
When the temperature rises again – but no later than after 30 minutes – the
HR 40 will resume normal operation.
Note: The window function can be ended at any time by pressing the
button or by turning the adjustment dial.
In order to protect the valve it is opened every Monday at midday.
cycl is displayed.
If the temperature drops below 4 °C, the HR 40 opens the radiator valve until
the temperature rises above 6 °C again. In this way, the HR 40 prevents the
radiator from freezing. The
symbol flashes as soon as frost protection is
Note: Frost protection only works with the operating unit attached.
The HR 40 will switch to summer or winter time automatically.
Battery change display
When the BaTT display flashes, the HR 40 remains functional. However,
you should change the battery as soon as possible.
If BaTT is displayed permanently, the HR 40 is inactive and the radiator
valve is opened (frost protection).