Effective heating controls are a vital part of an efficient system. Fully working controls can minimise energy consumption by ensuring everything is working at the right temperature. Built-in appliance controls will include the main on/off switch which controls whether the appliance is completely off or on stand-by until it needs to provide heat. The temperature controls are used to determine the heat output of the appliance in question. Some appliances may have have either a mechanical timer or a digital timer. The timer controls when an appliance will be switched on or off automatically.