Residential water heaters use oil, gas, or electricity to heat potable water to be used for such activities as bathing or washing dishes or clothes. Residential water heaters include storage type units that store heated water in an insulated tank and instantaneous type units that heat water on demand.
Water heating is typically the second largest energy use in a home, after heating and cooling, and can account for 14%-25% of household energy consumption. In the United States energy consumed by residential water heaters accounts for 11% of the electricity and 24% of the natural gas consumed in the residential sector. However, residential hot water use is variable and depends on the number of people in the household, the type of appliances, and the climate in which the house is located.
For more information, see the DOE’s Appliance and Equipment Standards for this product.