The ST699 is a 24-hour dual zone timer that is designed to replace the programmer on both gravity primary systems and fully pumped systems, with separate heating and hot water temperature controls. It will fit into the same backplate and is easy to programme with a slider switch, which includes plus and minus buttons. Programming your heating to come on as you wake up to a chilly home or return after a hard day at work has never been easier. Our customers find this one of our easiest to use models with no complicated programming to try and figure out.