A built-in fan draws ambient room or outdoor air into the top section of the unit. The air passes over an internal evaporator coil containing a cold, liquid refrigerant. Because this refrigerant has an incredibly low boiling point, even cool air contains enough thermal energy to cause it to evaporate and turn into a gas.
Temperature Boosting: The gaseous refrigerant enters the compressor. The compressor squeezes the gas, significantly raising both its pressure and its temperature.
Heat Transfer: This hot gas travels down through a condenser coil that wraps around or sits inside the insulated water storage tank. The heat from the hot refrigerant gas radiates directly into the domestic water supply, warming it up for use.