The nVent RAYCHEM ASD Controller is a UL Listed ambient sensing digital unit that allows on/off operation of RAYCHEM heating cables by energizing up to four (model ASD-4C) or eight (model ASD-8C) branch circuits according to the temperature set points on the digital temperature controller. A set point for heater on/off operation as well as a set point for low temperature cutout of the circuits are provided. The Low Temp Cutout mode serves to save energy by keeping the heaters off when temperatures are so low that no snow and ice melting occurs. Both temperature set points are easily field adjustable to suit local conditions.