Evaluation of the General Electric Heat Pump Water Heater

While electric water heaters are less commonplace in PG&E’s residential service territory than natural gas units, where they are used, they can represent a significant portion of a home’s electric demand (up to 5 kW). As a potentially large power user, electric water heaters are likely candidates for demand response (DR) measures when electric supplies are tight. A typical DR measure for a standard electric water heater would be to lock out the heating elements during the event (similar to the PG&E SmartAC devices that prevent operation of air conditioner compressors). Since most water heaters store thermal energy using a large volume of water, they may be able to pass through a DR event without using any energy, even without a device that locks out the elements. However, if there is a large demand for hot water during an event, the elements would need to activate or the user would eventually run out of hot water, which may not be tolerable to the user.