Water Heater Types
Storage tank water heaters are the most common type, heating and storing 40 to 80 gallons of water for on-demand use. The Energy Factor rating measures overall efficiency, with standard models achieving 0.60 to 0.70 EF and high-efficiency models exceeding 0.90 EF. Tankless or demand-type water heaters heat water only when needed, eliminating standby losses. They provide a continuous supply of hot water at flow rates of 2 to 5 gallons per minute depending on the temperature rise required.
Heat pump water heaters use electricity to move heat from the surrounding air to the water rather than generating heat directly. They are two to three times more energy efficient than standard electric water heaters, with Energy Factors of 2.0 to 3.5. The US Department of Energy estimates that a heat pump water heater saves the average household 300 to 400 dollars per year compared to a standard electric model.