Warmup Control Unit for Snow Melting and Roof & Gutter applications, 2 Zone control, 115/230VAC, 3 x 15 amp dry contacts. Works with ETOR and/or ETOG sensors. Requires external relay contactors to operate and switch loads/heating cables.Using readings from temperature and moisture sensors, the ETO2 ensures economical control of power consumption while keeping outdoor areas and roofs free of ice and snow. A moisture sensor is installed in the ground surface or placed in the gutter. As soon as moisture and low temperature is detected, the ETO2 activates the snow melting system.