What Is the Function of an HVAC System?

If you see the acronym, HVAC, and the words healthy, veins, arteries, and capillaries come to mind, you may work in the medical field. While you could compare ductwork—one component of an HVAC system—to arteries, HVAC has nothing to do with the human body.

Or does it?

Depending on the season, when HVAC systems function correctly, they do help keep the body comfortable, but it goes further than that! Today, we’re unpacking the facts about one of the essential home systems that normally works behind the scenes. Read on and explore the function of your heating and cooling system.

What Is an HVAC System?

Speaking of heating and cooling, HVAC systems do both.

The H in HVAC stands for heating. The remaining letters represent ventilation and air conditioning. The components of HVAC systems include either a furnace or heat pump, air conditioner, and ductwork.

Since it’s the most efficient way you can heat a cool a living space, you’ll find an HVAC system in every modern home.

The primary function of this critical home system is maintaining the air temperature inside your home at a comfortable level. In addition to temperature control, the HVAC system also keeps humidity at a healthy level.

There is one more thing the system takes care of—filtration. Without filtration, the system couldn’t remove dust particles and other contaminants. It also wouldn’t be able to manage excess moisture.

Putting Together the HVAC System Puzzle

Before we drill down to the specifics of how HVAC systems work, let’s look at the main components.


For heating, you’ll use a gas or electric furnace or a heat pump. Some homes have a dual fuel system, which uses a furnace and a heat pump.

If your system uses a furnace, an igniter and burners heat the air. Heat pump systems use evaporator and condenser coils. Depending on the setting, heat pumps can cool or heat your home.


The ventilation components include air ducts and vents, air filters, and exhaust fans. When the system works correctly, it moves warm or cool air into the rooms in your home. Then, it moves used air back into the HVAC unit to be heated or cooled again.

Ventilation also includes filtration, which removes contaminants and particles from the air so that you don’t need to worry about breathing in something that could cause harm to your health.

Air Conditioner

Your air conditioner not only cools your home, but it also controls humidity. Most systems have an inside and an outside unit. The inside unit consists of the evaporator coils and expansion valve, while the outdoor unit contains the cooling fan, compressor, and condenser coils.

Although the AC does help maintain healthy humidity levels, you do need some moisture in your home. If your home feels too dry, you may need to use a humidifier as well.

Your climate, size of your home, and budget determine the type of system you install in your home. Read on to learn about another popular heating and cooling solution—the ductless system.

Ductless Heating and Cooling Systems

Were you aware that your home loses 25% to 40% of its heating and cooling energy through the ductwork, especially through ducts located in attics and crawlspaces? One answer to this energy loss problem is installing a ductless HVAC system.

Some ductless systems only consist of air conditioners, but homeowners living in colder climates can benefit from a ductless system that includes a heat pump. A ductless system includes:

  • Wall-Mounted Indoor Unit
  • Outside Compressor

As the name implies, these systems don’t include air ducts or vents. Because they don’t use ductwork, you won’t deal with as many air leaks. Ductless systems also have a smaller footprint and make less noise.

Another unique feature of ductless HVAC systems is the compressor. They use inverter-driven compressors, which speed up and slow down based on system needs. The compressor in a standard HVAC system shuts down entirely, forcing the system to consume large amounts of energy whenever it starts up again.

Energy efficiency and consistent cooling and heating make ductless systems an excellent option if you’re considering updating your HVAC system.

A Word About Ductwork

We already talked about ventilation components and touched on their function. Now, let’s drill down a little further into ducts and vents.

Ductwork distributes air from the HVAC system to every room in your home. The system also sucks air from inside your home back into the AC or furnace. There, it’s cooled or heated before it’s pushed back out through the ducts into your home.

Air moves through the ductwork through supply and return vents as a way to circulate air.


Supply vents connect to your supply ducts. They supply your home with conditioned air. Most supply vents use louvers, which you can adjust to direct airflow. If you’re not sure which vent is a supply vent, hold your hand up in front of a vent—air blows out of a supply vent.


Return vents connect to return ducts. They pull air from your living space and move it back to the heating or cooling unit. Return vents are larger than supply vents, and they don’t use adjustable louvers.

If you hold your hand up to a vent and feel suction, you’ve found a return vent. Of course, any feeling of air coming and going from vents depends on you turning on the system’s fan.

Air Filters

You didn’t think we wouldn’t talk about air filters, did you? The air filter plays a significant role in the ventilation component of your system. It traps the debris and contaminants floating in your air so that they don’t enter your indoor airspace.

Most homeowners can tackle changing the air filter without much assistance. To ensure your system runs efficiently, it’s a good idea to change the filter at least every three months and sometimes more frequently depending on filter type. This is the best preventative maintenance that can be done for your HVAC system and it’ll help you avoid major repairs in the future.

Ready to Buy New HVAC System Filters?

We hope you feel like you have a better understanding of how your HVAC system works. Once you understand the basics, you can feel confident taking on minor troubleshooting if you experience system issues.

Here, at Discount Filters, we specialize in helping customers select the correct filter for HVAC systems and other home appliances. We’d love to welcome you into our family of satisfied customers and invite you to shop our selection of AIRx HVAC filters that are made right here in the USA.

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