The Bosch Compress HP 200-1 water heater is a heat pump water with a 50 gallons storage tank and an energy factor of 2.2. If you're shopping for a new electric water heater, check out the other electric heat pump water heaters to get a good comparison.
From the Rheem website:
"The Rheem Hybrid Electric Water Heater features heat pump technology that makes it over TWICE as efficient as standard electric water heaters"
And from their How It Works section:
"Rheem air-source heat pump water heaters work much like a refrigerator in reverse. The heat pump extracts the heat from warm air, intensifies the heat with a compressor, delivers the heat to the water, and exhausts the cooler air. Because it uses the warm ambient air temperature to do most of the work, it is a very efficient way to heat water."
GE describes how the unit works in the GeoSpring Hybrid water heater features:
"A compressor and evaporator are integrated into the electric water heater unit and the evaporator draws in ambient heat from surrounding air using two variable speed fans. Condenser coils wrap the tank all the way to the bottom to transfer this heat into the tank and heat the water.
