Brooklyn Plumbing Co 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.
How a Water Heater Works:
Water heaters are not really all that mysterious. A water heater heats water on a continual basis, whether you are using hot water or not. When you draw off hot water, cold water enters the tank to replace the hot water drawn out. When the thermostat senses the water temperature has dropped below the hold level, it initiates the heating elements in an electric water heater or the burner in a gas model.