On SR500 panel press and release the heating cable button (the second from left). To adjust the increments of the heating cable work use + and – buttons.
On SR501 press and hold the heating cable button for 3 seconds (the top middle button). To adjust the increments of the heating cable work use middle top and bottom buttons.

The heating cable will work non-stop if 0 is chosen. In that case the owner must be attentive and turn it off when no more needed. The cable’s work duration is 10 minutes while the pauses are set by the user. In the active state the cable periodically turns on and off. To stop it just press the appropriate button.