The Basics of HVAC Systems: A Comprehensive Guide for Beginners

The home’s HVAC system is critically important for the comfort and air quality of the home. Homeowners must take proper care of the equipment so it continues to work at peak efficiency. First-time homeowners may be unfamiliar with HVAC fundamentals, and that can lead to skyrocketing utility bills and the need for costly repairs. So, we have put together this HVAC for beginners’ guide to help you understand the HVAC basics that will help keep your system running smoothly throughout the year.

What Is an HVAC System?

HVAC stands for heating, ventilation, and air conditioning. Your home’s HVAC system includes all the equipment responsible for the heating, cooling, and air circulation within your home. The HVAC basics encompass the furnace, the air conditioner, and the ductwork that connects them throughout your home.

While most people think of the HVAC fundamentals as heating or cooling, the ventilation component is essential. Your HVAC equipment forms a closed system. The air within your home is drawn into the HVAC equipment, where it is heated or cooled, filtered, and then returned to your living space.

The air filtration function and ventilation are critical to maintaining your indoor air quality. Dust, mites, pet dander, and various allergens and particulates are filtered out of your home’s air as it is circulated by the “V” in HVAC. Further, the ventilation also helps control moisture levels and humidity in the home while helping to remove odors. The ventilation equipment also manages carbon dioxide and other pollutant levels.

Beyond the heating and cooling we crave, the HVAC system is vital to the health and comfort of the home’s residents.

Essential HVAC Components

Basic HVAC knowledge includes an understanding of the primary system components and what they do, as outlined below:


Refrigerant is what makes air conditioners produce a cooling effect. It is a chemical in liquid form that absorbs heat as it evaporates. The HVAC system then compresses the refrigerant back into a liquid, expelling the absorbed heat outdoors.

Evaporator Coils

Evaporator coils in an HVAC system consist of copper tubing that carries the refrigerant. As the system draws in air from the home, this air passes over the cold evaporator coils. The heat from the air is absorbed by the refrigerant in the coils, causing the refrigerant to evaporate within the coils. This process removes heat from the air, cooling it. The cooled air then circulates back into the home. These HVAC basics for cooling air apply to all air conditioners.


After the refrigerant absorbs heat from the home’s air and evaporates in the evaporator coils, it enters the compressor as a gas under low pressure. The compressor increases the gas’s pressure and temperature, preparing it for the condenser.


The refrigerant enters the HVAC condenser as a gas under high pressure. As it passes through the copper condenser coils, the refrigerant releases its heat, cooling it down so it reverts to a liquid form. The condenser unit is located outdoors and releases the heat into the environment.

Furnace/Heat Pump

The heating in a traditional HVAC system is done by a furnace that heats the air. Newer systems in mild winter climates use a heat pump in place of the furnace and the air conditioner. Heat pumps utilize the HVAC compressor and condenser for cooling, as described above, and then they reverse the action for heating.


The HVAC system ductwork circulates the air in your home through a series of ducts or conduits.


A vent is the opening where the ductwork allows air to pass into the home. Your home might have vents in the ceiling, floor, and walls.

Blower Motor

The HVAC blower motor turns the fan that circulates hot or cold air throughout your home.

How Does an HVAC System Work?

Now, let’s put the HVAC basics together. The blower motor draws your home’s air into the HVAC system. The air is drawn over the evaporator coils, where it sheds heat to the refrigerant in the coils. Then, the cool air is blown through the ductwork and out the vents into your home. For heating, in systems with a furnace, the air passes over a heat exchanger, which warms the air before it circulates back into your home. With a heat pump, the heating process is the reverse of the cooling.

Types of HVAC Systems

Armed with this basic HVAC knowledge, let’s briefly review several types of HVAC systems.

Cooling & Heating Split Systems — Central

The traditional HVAC system used in the U.S. is the cooling and heating split system, commonly referred to as “central air.” It consists of an indoor unit with the furnace and evaporator coils and an outdoor unit that houses the compressor and condenser.

Hybrid Split Systems

The hybrid split HVAC system is a newer, more energy-efficient system for mild winter climates with moderate temperatures. They combine a traditional gas furnace with an electric air-source heat pump. The system then switches between gas and electric power to optimize efficiency based on the prevailing weather conditions.

Ductless Mini-Splits

The ductless mini-split is a newer and smaller version of the classic HVAC split system that works without ducts to circulate the air. Hence the name “ductless mini-split.” They have an outdoor unit containing the condenser coils and compressor and an indoor unit housing the evaporator coils and fan. Electrical wiring and refrigerant tubing connect the two units, delivering heated or cooled air directly to specific rooms.

Packaged HVAC Systems

Packaged HVAC systems combine all their components into a single outdoor unit. These are used in places with limited space for indoor HVAC components.

Geothermal HVAC

Geothermic HVAC systems are modern, highly efficient heating and cooling systems. They harness the naturally stable temperature of the earth itself for heating and cooling through a series of underground pipes.

Difference Between HVAC and Air Conditioning

Now that you’ve mastered HVAC basics let’s have a quick quiz: What’s the difference between HVAC and air conditioning? An HVAC unit contains heating, ventilation, and air conditioning equipment. Air conditioning refers solely to the equipment that cools the air in your home.

Stay Comfortable Year-Round With Professional HVAC Services

At Aire Serv®, we do more than teach homeowners HVAC basics. Our service professionals deliver comprehensive HVAC services throughout the country. Our heating and cooling services include installation, maintenance, repair, and replacement of every component of your system. Trust your local Aire Serv for your residential or commercial HVAC services.

As proud members of the Neighborly community of home and business service brands, all our work is backed by the Neighborly Done Right Promise™. We know the job isn’t done until it’s done right.

Contact your local Aire Serv today to request an appointment.