Electric water heaters

The term "electric water heater" usually refers to a tank-type water heater that relies on electricity as a heat source. Tank-type water heaters are also known as "storage water heaters," since they are designed to store hot water until someone turns on a hot water faucet, washing machine or dishwasher.

Like other tank-type water heaters, an electric water heater has a thermostat and a temperature control. When the water in the tank cools below a preset temperature control, the electric heating element goes on automatically and stays on until water temperature rises to the preset level. To help reduce standby heat loss (and save energy), an ENERGY STAR®-rated tank-type water heater has a thick layer of insulation on the outside of the tank. But even with ample insulation, the efficiency of an electric, tank-type water heater is limited because when the water in the tank eventually cools, it must be reheated.

Replacing an old electric water heater is an opportunity to save energy

Most electric, tank-type water heaters need to be replaced after about 15 years. An older tank-type water heater will consume more energy than it should (compared to current ENERGY STAR models). An old tank-type water heater also has the potential to start leaking because of corrosion on the tank interior. Since heating water for domestic use can account for as much as 15% of a household's total energy expenses, it makes sense to replace an old water heater with a more efficient model. The chart at right will help you select the right tank size based on how many people are using hot water.

NOTE: Heat pump water heaters are also powered by electricity, and store heated water in a tank. To achieve a much higher level of energy efficiency when replacing an old electric, tank-type water heater, consider purchasing a new heat pump water heater.

Electric water heaters at a glance