After the batteries have been inserted with the correct polarity, either a symbol or the target temperature appears on the display.
If the display shows nothing or F4, the batteries are empty or nearly discharged and must be replaced.
A red flashing LED with simultaneous display of F2 indicates too large a distance between control pin and valve. Check the tightness of the screw connection.
F1 in the display means that the valve is too stiff or the valve drive is blocked. In this case, check the valve and adapter.
Please contact the technical hotline for further informations.