In this article, you’ll learn the basics of HVAC, which stands for heating, ventilation, and air conditioning.

Our heating and cooling experts get a TON of questions from people trying to figure out how to heat and cool their homes appropriately and what components they need. Below, we cut through the complexity to explain your main options.

For simplicity, this article focuses on heating and cooling with air. If you’re interested in hydroponics, check out our boiler system buying guide. For more on ventilation, read our Ventilation Guide.

 

The Main Types of HVAC Systems

At the highest level, there are two different types of forced air HVAC systems: split systems and packaged systems.

Their names explain what they are. Split systems are “split apart,” meaning part of the system is outside the home and the other part is inside the home. Packaged systems package all HVAC components into one outdoor unit.

Now, let’s look at split systems specifically before discussing packaged systems later on.

 

Types of Split HVAC Systems

Most people with average-sized homes have split systems that separate the HVAC components. These can take one of five main forms.

Gas Furnace, Coil, and Air Conditioner

In this setup, a gas furnace and evaporator coil are inside the house (indoor unit), and an air conditioning condenser is outside (outdoor unit).

When it’s cold, the furnace burns gas to create heat, and a fan pushes this heat through air ducts that go to different parts of the building.

When it’s hot, the indoor evaporator coil removes heat from the indoor air using refrigerant. The fan circulates the cooled air (after the heat has been removed) through the building. Meanwhile, the heat flows via a refrigerant line to the outside condenser, which then releases the heat.

If you’re confused about the refrigerant part, read our central air conditioner buyer’s guide.

Pros:

• Lower upfront costs

• Provides both heating and cooling

Cons:

• Less efficient

• Higher energy costs
  

Electric Heat Pump and Air Handler

In this configuration, a heat pump sits outside, and an air handler sits inside. Both the heat pump and air handler include built-in evaporator coils.

When it’s cold, the heat pump’s evaporator coil takes heat from the outdoor air and pumps it to the indoor air handler. The air handler uses a fan to spread the warm air through the building’s ductwork.

When it’s hot, the opposite occurs. The air handler’s evaporator coil absorbs heat from the indoor air and sends it to the heat pump outside, which releases it. The newly cooled air circulates around the home.

Read Central Heat Pumps 101 to learn how heat pumps work.

Pros:

• Fewer components

• More efficient

• Lower energy costs

• Provides both heating and cooling

Cons:

• Higher upfront costs

• May require supplemental heating in extremely cold climates
  
  

Electric Heat Pump, Coil, and Furnace

These hybrid split systems are becoming more common in extremely cold climates. They work the same way as a heat pump and air handler combination, except they use an indoor furnace instead of an air handler.

More importantly, the furnace provides supplemental heat if the heat pump isn’t enough. If you regularly see the thermostat dip into the negatives during wintertime, this setup is likely for you.

When it’s cold, the heat pump takes heat from the outdoor air. It then sends this heat to the indoor evaporator coil. The furnace's fan blows the warm air through the building’s ductwork.

If it’s exceptionally cold and using the heat pump alone isn’t enough, the furnace can step in to provide enough heat.

When it’s hot, the coil extracts heat from the indoor air and sends it to the heat pump outside, which dissipates it. The cooled air circulates around the home.

Pros:

• Efficient when using the heat pump

• Provides both heating and cooling

• Provides supplemental heat in extremely cold climates

Cons:

• High upfront costs

• Using the furnace cuts efficiency
  
  

Air Conditioner and Air Handler

This setup does not have heating, which makes it most common in consistently hot climates like southern Florida.

The air handler has a built-in evaporator coil. This coil removes heat from inside the building. It then moves the heat to the outdoor air conditioner condenser, which releases it. The air handler’s fan simultaneously circulates the newly cooled air through the building’s ductwork.

Pros:

• Lowest upfront and energy costs

Cons:

• Requires a supplemental heat source, such as an electric heat kit, on cold days
  
  

Ductless Mini Splits

Ductless mini splits operate similarly to a heat pump and air handler, except they are not a centralized system. Instead, they heat individual spaces in the home without using ductwork (although a ducted option is available).

In the most basic mini split setup, one condenser unit is outside, and one indoor air handler unit is inside. This is called a single-zone mini split system.

When it’s cold, the mini split condenser takes heat from the outdoor air. It then pumps this heat to the indoor unit. The indoor unit uses a fan to blow the heated air into one room or space.

When it’s hot, the indoor air handler’s evaporator coil takes heat from the indoor air. It sends this heat to the heat pump outside, which releases it. Meanwhile, the indoor unit’s fan blows the cool air into a room or space.

Mini split systems can get much more complicated. You can have two, three, four, or five separate indoor units conditioning separate zones of a building differently, all connected to a single outdoor condenser. In very large homes or buildings, there might even be multiple condensers, each connected to multiple indoor units.

Learn more in our Ultimate Mini Split Guide.

Pros:

• Most efficient heating and cooling system

• Lower energy costs

Cons:

• High upfront costs
  
  

Packaged HVAC Systems

Packaged HVAC systems combine or “package” all heating and cooling components into one unit that’s installed outside. There are three main configurations:

• Packaged Air Conditioners combine an air handler and condenser. They only provide cooling, so they are best in consistently hot climates.

• Packaged Air Conditioner and Furnace Systems combine a furnace, coil, and condenser for heating and cooling.

• Packaged Heat Pumps combine a heat pump condenser and air handler for the most efficient heating and cooling.

Packaged systems are best for homes and buildings with limited indoor space or for rooftops. Since they are a single unit, they are easier to install and access for maintenance. However, they constantly face the elements and offer less room for customization than split systems. Read Packaged Units 101 to learn more.

 

The Bottom Line

You should now understand the different types of split and packaged HVAC systems. Choosing the right one will depend on your climate, available space, and the cost of electricity versus gas in your area.

You should also decide whether you prefer lower upfront costs but higher utility bills or paying more upfront but saving energy long-term.

If you have questions about HVAC equipment or need help putting together a package, our experts are ready to help. Contact us today!

 

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