A line voltage thermostat 120V is a device that is used to control the temperature of a space by controlling the voltage of the electrical line. It works by using a temperature sensor to detect the temperature of the space and then sends a signal to the thermostat to adjust the voltage of the electrical line accordingly. This type of thermostat is typically used in residential and commercial buildings to regulate the temperature of the space. It is important to note that the voltage of the electrical line must be within the specified range for the thermostat to work properly. In addition, it is important to make sure that the thermostat is compatible with the electrical system in the building in order to ensure that it functions properly. Line voltage thermostats are an efficient and cost-effective way to maintain the desired temperature in a space, and they are easy to install and use.