A.O. Smith’s Voltex Water Heater

Voltex is a hybrid electric water heater that integrates heat pump technology to make it more than twice as efficient as a standard tank. The unit operates like an air conditioner in reverse, pulling heat from the surrounding air and transferring it to the tank. It costs about $200 per year to operate, the company says. A.O. Smith, 414.359.4000; www.aosmith.com.