The ESRTD3 is a mains powered Electronic Room Thermostat with Delayed Start that is economical and simple to use. Simply turn the control dial to the desired temperature to control the room temperature. The ESRTD3 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 TPI & Delayed Start option provides potential energy savings and SAP points, with the opportunity to save up to 10% on heating costs. The TPI feature increases boiler efficiency by firing the boiler at regular intervals, adjusting firing duration with demand, to maintain set room temperatures, giving them a great advantage over other domestic room thermostats and achieving a constant ambient environment for the user. The Delayed Start feature delays the start-up of the heating, depending on how warm the room temperature is at the time when the central heating is due to come on. The heating start can be delayed for up to 45 minutes if the room is already relatively warm, when the weather is milder for example. This often reduces how long the heating is on per day, with no comfort loss, saving energy and money. The delayed start feature can be fully automated and needs no extra programming.http://www.esicontrols.co.uk/esrtd3.html