The latest setting for on/off is 11.50pm and the earliest setting is 12.10am. From Monday to Friday I have the heating set to come on at 6.30am (on1), go off at 8.00am (off1), come on at 3.30pm (on2) and go off at 11.50pm (off2) To acheive this, the CH switch should be set at the "Twice" position and the main switch set at "Auto". If for any reason I am home between"off" and "on" times, you only need to press the CH Over Ride button and the central heating will come on and not go off until one of the pre-set off times is reached.
If you want the heating on constant all you have to do is select "24 Hours" and put the main switch at "Auto".
To select on/off times, you need to select the correct day of the week by using the "Day" button. The day of the week will appear on the top line of the display window. You can now select the on/off times by putting the main switch to the on and off positions and using the "Forward" and "Reverse" buttons to select the required times
Mike Partington, December 2007