There are 2 types of programmers, a mechanical timer or a digital timer. They both do the same job, which is to tell your heating system when to come on and off.
It takes approximately half an hour for your home to heat up or cool down, so its a good idea to set your programmer to come on half an hour before you want your home to be warm and to go off half an hour before you go to bed in the evening.
If you are out of the home all day, don’t leave the heating or hot water on as this is a waste of energy and will just cost you more on your fuel bills. Set your programmer to come on when you are in during the day or due to return.
You can download these documents which explain in more detail how to use your mechanical and digital programmer:
How to use your Mechinical Programmer [docx] 315KB
How to use your digital programmer [docx] 124KB