The gas boiler thermostat is with an LCD digital display screen.The thermostat detects room temperature, when actual room temperature is lower than your setting temperature, the thermostat controls boiler to start to operate.Then the thermostat controls boiler to stop working when actual room temperature is higher than your setting temperature.It is with 1.5V two sections of AA batteries (not included).It is used to control boilers to start or stop working in order to adjust temperature.Specification:Voltage Working: 2 x 1.5V AA battery (not included)Power consumption: 150UWTemperature control range: 5 ~ 90 , (the setting Factory temperature is 5 ~ 35 )Temperature limit range: 5 ~ 90Temperature control accuracy: & Plusmn; 1Size: 85 x 85 x 28 mmSensor: integratedWhite colorBacklight:< p>Package includes: 1 x gas boiler thermostat2 mounting screws1 x English instruction1) Convenient to mount on the wall or stand somewhere.2) Battery free, powered by battery, can put anywhere you want.3) Can set 5+2/6+ 1/7 weekly programmable.4) Children lock to avoid incorrect operation.5) Anti-freeze function.Hand control: For boiler general gas, it can be connected with NO COM terminals! (NC terminal is for special gas boiler.) The installation wires should be chosen to be 1.5-2.5mm2 hard. Please rightly connect the wires strictly according to the connection diagram. Do not put mud, other debris into the thermostat, otherwise it will damage the thermostat.