How Residential HVAC Systems Work

It is a mystery to many of us about how a home Air Conditioning system works. Different kinds of furnaces are easy to understand as its process is they heat air and blow it out of your house. Boiler’s process is making water hot or steam and move it around your house with the help of pipes. The question here is how an Air Conditioner works. For understanding it, you need to recall the principle which everyone has learned in high school at any point of time in physics class. Everyone is familiar about the basic property of gas that as it expands it cools down. The basic principle is explained in a simpler way below:

The Basic Principle

For understanding the process of Air Conditioner, you can think it as a machine that takes heat from your house and dumps outside by using different interrelated parts.

These parts are:

  • Evaporator coil
  • Expansion Valve
  • Refrigerant
  • Condenser
  • Compressor

How Heating & Air Conditioning Systems Work

There are many other types of air conditioning systems that can be used by the residents which includes window units, ductless air conditioners, central Air conditioning systems and portable air conditioners. All of these are different air conditioning systems, however the physics principle used behind these systems are the same. They all use the same following components and direct expansion refrigeration. All the components which are used in an air conditioning system is explained below:


Heat Pump Schematic

The compressor is the heart of the Air conditioning system. You can think of the compressor as the heart for understanding it better. The compressor pumps the refrigerant through all the refrigeration components in a large copper loops. The refrigerant then enters the compressor as a low pressure warm vapor. The warm vapor is then released as a high pressure hot vapor.


The refrigerant can be thought of as the blood that is pumped from the heart (Compressor). The refrigerant is pumped with the help of cooling tubes in the AC system. The refrigerant changes the state from gas vapor to liquid as it collects heat from your house. Refrigerant is a unique substance and has a very low boiling point. This feature helps it to change liquid into a vapor form at a low temperature.


Hot refrigerant vapor from the compressor then moves to the condenser. In the condenser the high pressure hot refrigerator is cooled as the condenser fan blows the air over the condensing coils. As the refrigerant cools down, it changes the hot vapor to a hot liquid a t a higher pressure onto the expansion valve.

Expansion Valve

The expansion valve is an important part of an air conditioning system. As the hot liquid from the condenser passes through the tiny opening at high pressure in the valve. It then emerges as a cool mist. The Air conditioner is nothing more than a device designed to force the refrigerant gas to expand.

Evaporator Coil

The low pressure cold liquid which leaves the expansion valve runs through the evaporator coil. In the evaporator coil, the hot air your home blows across the coil and heats it up. While the same time the coil which carries the cold expanded gas cools off and the air blows across your home.

Evaporator Coil - Heat Pump

Call Bair Necessities Today!

Call us today for a system checkup to make sure that your air conditioning system is up to par and ready for the rest of the winter season and this upcoming spring!

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