Abstract: A heating device for installation on the roof of a structure to permit water to flow off the structure from behind a blockage of ice. An elongate, hollow tubular member defines a chamber in which is situated a point heat source. A jacket of insulative material surrounds the tubular member to retard heat loss. One side of the jacket faces the roof and has a channel open to the tubular member such that heat transfer from the tubular member occurs primarily through the channel. When the device is installed on a roof, heat radiated through the channel forms heated passageways through the ice blockage for escape of water.