What Is A Condensing Unit?

Among the great inventions that are used across multiple industries is the condensing unit, otherwise referred to as a condenser. This technology specifically reduces (condenses) gas or vapor into liquid in order to keep a larger device cool. In power plants, refrigeration plants, and distilling facilities, condensers convert turbine exhaust steam, refrigerant vapors, and alcohol (respectively) into liquids. However, you might be more familiar with its use as a vital component of your HVAC system — whether it's for your home or business. During the manufacturing process of air conditioners and heat pumps, for instance, the condensing unit is constructed with fins and a series of coils for efficient temperature control. 

The role of the condenser in an air conditioning system — the outdoor part of your HVAC equipment — is to remove gaseous heat from the system's refrigerant (such as R134a and R410a), which absorbs indoor heat. It enters the condenser through a heat-conductive metal, such as copper coils. Then, as the fans blow the heat outdoors through the fins, the gas returns to liquid form and continues moving through the system. As a result, cool air is blown into your space to reduce the temperature and keep you comfortable. The condensing unit in a heat pump works the same way, except that the heat in the refrigerant comes from the outdoors and is released into your living or working space.

Alongside your HVAC system, condensers are used in another major household appliance: the refrigerator. It's an essential component to keep the inside of your fridge cool. But, while all condensing technologies remove heat from vapors and return the gas to liquid form, there's a slight difference between the condenser in your air conditioner or heat pump and the one in your kitchen. The construction is the main difference — mostly a set of coils on the back of the appliance, which is why it's important to have good airflow behind your refrigerator.

After low-pressure vapor goes through the refrigerator compressor, it comes out as high-pressure vapor that passes through the condenser coils, which are usually metal to facilitate heat transfer. The hot gas naturally loses heat in the coils, which are exposed to air outside of the appliance. Along the way, the vapor turns back into a high-pressure liquid that enters an expansion valve, which cools the refrigerant quickly and sends it into an evaporator as a low pressure liquid. There, it absorbs heat from inside the refrigerator while undergoing a type of vaporization, and the process repeats.