A thermostat, as well as the system you are about to implement is an example of a control system. Simply put, a control system is a system that, based on a number of inputs, continuously decides on a value for one or more outputs. Most control systems are closed loop control systems (also known as feedback control systems), meaning that their outputs also influence the inputs, providing the system with feedback about the decisions it makes.

In this case, the inputs are the current temperatures and the setpoint temperature, and the single output is whether the heating system should be on or off. The feedback happens when the temperature changes due to the heating being on or off.

A lot of different sorts of control systems have been designed and documented but, like most on/off thermostats, this example will use a simple hysteresis controller. Consider the following approach: If any rooms have a temperature below the setpoint, turn the heating on; if all rooms are above the...