The air source water heater follows the "reverse Carnot" principle, where the "outdoor unit" works as a heat exchanger that captures the heat from the outside air. It then heats the low boiling point working medium (refrigerant) and evaporates it. The refrigerant vapor undergoes compression where it is heated, and later enters the water tank to release the heat to the water. The refrigerant then condenses and liquefies, goes through throttling to achieve a lower temperature, and returns to the outdoor heat exchanger to start a new cycle. In essence, it harnesses the heat in the air to provide hot water, and the air can also be utilized in the kitchen to combat the issue of stuffiness.