Tekmar 665 Snow Detector & Melting Control Pulse Width Modulation The Snow Detector & Melting Control 665 is designed to operate mechanical equipment to melt snow off an outdoor slab. It can be used in hydronic or electric snow melting applications. This product uses a tekmar snow/ice detection sensor in order to automatically melt snow using Pulse Width Modulation (PWM) and slab Outdoor Reset to maintain slab temperature. It is capable of controlling a single boiler, a system pump, and providing a signal when melting is enabled.