Controllers can consist of either timers or programmers. The difference between a timer and a programmer is that a timer allows you to set the central heating timings for only one day, whereas a programmer allows you to set different central heating and hot water timings for different days of the week.
By choosing a programmer you are able to adapt the system to suit your lifestyle generating the greatest savings. Modern programmers are now beginning to include weather compensating controls to further increase the efficiency of your boiler and reduce your gas bills.