Timer for central-heating systems

To achieve a comfortable room temperature quickly it is often required to switch on the central heating (CH) boller tor ten minutes or so, tor instance, in the morning, or when you get horne from work. Unfortunately, most CH systems can be switched on only by turning up one of the room thermostats. This works, but it you forget to turn it down again, the resultant hothouse is not only unhealthy but also a waste of energy.