The pins are on the outer ring above the dial with the numbers on (which slides) push in and out. This can be set to tell the system what time to automatically go on and off. Now the real time of day is set (as shown in first foto) you can push the pins in to tell the heating what time to automatically come on. It is a 24 hour clock. If I want the heating to come on at 1415pm and go off at 1630pm I push the pins in from 1415 pm and all of the pins in, up until the 1630pm
