Copper heaters were the only method of heating large amounts of water

Copper fiber film heaters were developed based on electrospinning and electroplating of copper fibers. They exhibit high heating performance, remarkable stretchability, and stability over 1000 cycles of bending. These copper heaters are highly resistant to moisture, and are available in wide temperature ranges. Electrospinning of copper fibers results in virtually seamless junctions, which greatly improves the transmittance and electrical conductivity of the film.

Copper fiber film heaters were investigated to determine their thermal stability. They were subjected to a 20-cycle stretching test at varying voltages, ranging from 30 to 107 degC. The heating performance remained stable throughout the tests, and no copper oxidation was detected (Supplemental Table S3).

In the past, copper heaters were the only method of heating large amounts of water. In Victorian, Edwardian, and early 20th century periods, copper water heaters were the only option for providing hot water to large numbers of people. Before the invention of gas-fired copper heaters, people used kettles over their kitchen ranges or fires. Fortunately, these types of heaters were not so heavy and could heat large amounts of water in a relatively short amount of time.

Copper heaters are also useful for heating large amounts of subterranean earth. The electrical resistance of the copper-nickel alloy heating cable is low, which makes it an excellent choice for subterranean applications. They can heat intervals of a thousand feet or more.