Assumes a 50° temperature rise from 70° fahrenheit to 120° fahrenheit.
For gas-powered water heaters, it takes approximately 584 British Thermal Units (BTUs) to heat 1 gallon of water for this 50° temperature rise.
For heat pump water heaters, it takes approximately 0.1 kilowatt-hours (kWh) of electricity in heat pump-only mode to heat 1 gallon of water for this 50° temperature rise.
For electric resistance water heaters, it takes approximately 0.4 kilowatt-hours (kWh) of electricity to heat 1 gallon of water for this 50° temperature rise.