The ESRTD2 is a battery powered Electronic Room Thermostat that is economical and simple to use. Simply turn the control dial to the desired temperature to control the room temperature. The ESRTD2 includes a LCD display which displays the current room temperature. When the temperature is adjusted, the LCD display will briefly show the revised temperature before returning to the current room temperature. A small flame symbol will appear on the LCD display when the system is being turned ON (if calling for heat when turning the temperature up). When the system is being turned OFF (if not calling for heat when turning the temperature down), the flame symbol will no longer show on the LCD display. The modern and stylish range of Electronic Room Thermostats from ESi Controls are designed to outperform many older thermostats and should be able to produce savings in the order of 10% over and above those achieved by traditional units using older technology. The temperature control accuracy of /- 0.6°C will reduce the temperature swing that normally occurs with older style thermostats.http://www.esicontrols.co.uk/esrtd2.html