Apart from heating and cooling the house, water heating is one of the biggest energy drains in the average home. But what if you could literally use cold water to create hot water? That’s just what San Diego inventor Hal Slater claims to have done with the creation of a water heater system that promises to improve water heating efficiency by as much as 50 to 100 percent. The system works on the basis that cold water supplied to households in temperate climates averages around 70° F (21° C), which the researchers say is 15° to 20° F (8° to...