The condenser coil receives the high pressure high temperature refrigerant vapor from the compressor and immediately begins to remove heat from the refrigerant vapor. As the refrigerant vapor makes its way through the condenser coil more and more heat is removed and the refrigerant vapor changes state from a refrigerant vapor to a refrigerant liquid. While the liquid refrigerant changes temperatures from a higher temperature to a slightly lower temperature the pressure remains constant. As the refrigerant vapor leaves the condenser coil it makes it way to the metering device.
Most condensing units utilized in HVAC whether it is the commercial HVAC field or the residential HVAC field are constructed of copper with aluminum fins. The aluminum fins are mechanically attach to the copper tubes that make up the condenser coils or the piping that channels the refrigerant from the beginning of the condenser coils all the way to the end or exit of the condensing unit where the refrigerant makes its way to the metering device. The aluminum fins attached to the copper pipe enhance the heat exchange process in the air source condensing units. A few manufacturers use only aluminum coils in their condensing units to take advantage of the efficient heat exchange properties of aluminum. The aluminum coils also have fins on them and these are usually referred to as spine fin coils. The spine fins extend the surface area of the aluminum coil enhancing the heat exchange process for efficiency purposes.
Many condensing units also house the compressor and condensing unit controls. The condensing typically utilizes its own dedicated circuit from the main circuit breaker panel. In a split system the condensing unit will have a line set or refrigeration lines that run from the condensing unit to the evaporator coil inside the building. The condenser is an essential component of vapor compression refrigeration.