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8 Common Types of HVAC Systems and How They Work

8 Common Types of HVAC Systems and How They Work

If you have ever lived or worked in extreme temperatures, you have likely encountered some type of HVAC system. HVAC systems are designed to keep spaces warm or cool, and building owners can customize them to fit specific temperature control needs.

“HVAC” stands for heating, ventilation and air conditioning, and refers to any system that provides ventilation or temperature control for a space. These systems include everything from central air and heating to portable space heaters and AC units, and there are multiple types to choose from.

Each type of HVAC system falls into one of two categories: ducted or ductless. In a ducted system, the main unit pushes air through a series of air ducts to cool or heat a building. Ductless systems, on the other hand, lack air ducts and use alternative methods to distribute treated air throughout a space.

To help you determine which heating or cooling system is best for you, we’ll go over the most common types of HVAC systems and explain how each one works.

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Types of Ducted HVAC Systems

Illustrations of a split, hybrid split, packaged heating and cooling, and zoned system

If a building uses vents to pump out hot and cold air, it is likely equipped with a ducted HVAC system. Ducted HVAC systems are standard in residential and commercial buildings and include any heating or cooling system that distributes air through a series of air ducts.

1. Split System

Heating and cooling split systems are the most common types of HVAC systems used in residential buildings. They consist of two separate components — one for heating and one for cooling — and use a traditional thermostat to control the temperature for the entire structure.

In most buildings with split systems, the heating unit is located in a basement, utility closet or other indoor storage space. The heater is gas-powered and uses an evaporator or fan to push heat through a building’s ductwork. On the other hand, the cooling system is located outside and connects to a building’s ductwork through a series of tubing. It uses compressors, coils and refrigerant to create cool air, and a fan directs hot air out and away from the building.

Key Feature: One thermostat controls the temperature for the entire unit

2. Hybrid Split System

A hybrid split HVAC system has the same structure and cooling unit as a split system but doesn’t rely solely on gas to create heat. While its heater can burn gas, it can also switch to electric power. Electric heating is often slower and less powerful than gas-powered, but this option gives building owners more control over their building’s energy consumption and can help reduce energy costs in milder climates.

Key Feature: Reduces energy consumption

3. Packaged Heating and Cooling

Packaged heating and cooling systems are less common than split systems, but their smaller size makes them better suited for small buildings lacking extra storage space. The heating and cooling components are housed in a single unit and are generally stored on a roof, in an attic space or near the building’s foundation.

Packaged HVAC systems connect to a building’s supply and return ducts, often through a single hole in the wall. Depending on the climate, building owners can choose to install a packaged heat pump containing evaporator coils or a packaged air conditioner with an air handler with optional heat strip elements. Both systems cost less to install than split systems and are easier to maintain.

Key Feature: Single unit is easy to maintain

4. Zoned System

HVAC zoning systems afford occupants greater control over the temperature in separate rooms or areas in a building. Technicians can zone ducted HVAC systems in a few different ways, and the best method often depends on the size of the building. For example, people who own larger homes may choose to install multiple HVAC systems to control the temperature on different floors. Because each system is completely separate, this type of zoning requires building owners to install two or more heating and cooling units.

Another common type of zoning involves installing manual or automatic dampers in a system’s air ducts to control the amount of airflow in different areas. Partially closing a damper restricts airflow to one zone while pushing it toward another, making it easier to adjust each room to its ideal temperature. This type of zoning creates a more comfortable environment for occupants and improves energy efficiency by directing air away from zones that don’t need it.

Key Feature: Allows for more personalized temperature control

Types of Ductless HVAC Systems

Illustrations of a duct-free mini split system, hydronic heating, a portable heat pump, and a spot cooler

As the name suggests, ductless HVAC systems are designed to heat or cool a space without air ducts. These systems come in various sizes and are commonly used in small buildings or temporary work sites.

5. Duct-Free Mini-Split

Ductless mini-split systems are installed in individual rooms and are common fixtures in multifamily homes, office buildings and hotel rooms. Also known as mini-split systems, these electric units include an outdoor compressor and condenser, refrigerant, an indoor air-handling unit, a heat pump, power cables and a thermostat for each zone. Copper tubing connects the indoor and outdoor components, and one compressor can connect to up to nine indoor air-handling units.

While duct-free systems can be expensive to install, they often help reduce energy costs and consumption over time. Their flexible zoning capabilities allow users to heat and cool occupied rooms only, preventing energy loss associated with ductwork. However, the heating components are less effective in below-freezing temperatures, so people living in colder climates often need to add a separate heating system.

Key Feature: Provides ductless temperature control for individual spaces

6. Hydronic Heating

Unlike the other HVAC systems in this list, hydronic heating uses liquid rather than air to radiate heat. This system uses a boiler to heat water, then distributes it throughout a building using a series of pipes under the floors. Once the liquid reaches a radiator or baseboard heater, it distributes heat throughout the room. Homeowners can also install a radiant flooring system that uses hydronic heating to heat their floors.

Key Feature: Uses liquid to radiate heat

7. Portable Spot Cooler

Spot coolers are portable AC units designed to cool down large rooms, manufacturing facilities or outdoor spaces. They work by drawing in ambient air, pushing it over a closed-loop coil cooled by refrigerant and pumping it back into the space. The coil cools and removes humidity from the air, creating leftover condensation that drains out into a hose or catch bucket.

Spot coolers can operate in any location with an electrical power source, and attached wheels make them easy to move. That said, finding a place to let out the exhaust can make setup in enclosed spaces more difficult. After cooling the air, spot coolers pump leftover warm air out through a flexible exhaust tube. This tube is usually extendible, and it must lead out through a door, window or drop ceiling to prevent warm air from re-entering the space.

Key Feature: Portable and easy to set up

8. Portable Heat Pump

A portable heat pump is similar in size and operation to a spot cooler but offers an additional heating option for colder environments. When switched to heating mode, a heat pump draws in outside air, runs it over a condenser coil and disperses warm air throughout the room. A reversing valve inside the unit allows users to switch between heating and cooling capabilities, making it a good option for varying climates.

Key Feature: Has both heating and cooling capabilities

Whether you’re installing a new HVAC system or need a temporary temperature control solution for your job site, there is an HVAC system out there that can meet your needs. If you need help deciding between the types of HVAC systems listed above, an HVAC specialist or contractor can help you find a compatible option for your building.

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