Ducted air conditioning is becoming ever more popular in Australia. It’s affordable, efficient, and suited to cooling larger spaces with multiple rooms, making it an obvious choice for anyone looking for a new air conditioner for their home.

But how does ducted air conditioning work, exactly? In this article, we’ll explore the science behind ducted air conditioning—how it works, the main equipment involved, common questions, and more.

What is ducted air conditioning?

A ducted air conditioner consists of two units—an indoor unit typically installed in the ceiling, and an outdoor unit. The two units work together to perform a refrigeration cycle, with conditioned air circulated and delivered via a series of ducts and vents. It’s usually the ideal system for larger buildings, due to its efficiency and ease of control.

How does ducted air conditioning work?

Ducted air conditioning is a refrigerated cooling system that uses refrigerant to change air temperature. Refrigerant is a substance that can easily change between gas and liquid, and as it goes through this process, it changes temperature. The ducted system uses this temperature change to cool or heat air that it pulls from the house.

The main components of refrigerated cooling systems are evaporators, compressors, and condensers. When on cooling mode, a simplified version of the refrigeration process in a ducted system works as follows:

  1. Evaporator: warm air is extracted from your home with a blower, which it transfers through ducts to the evaporator coils in the indoor unit. These coils contain cold, low-pressure refrigerant which absorbs the heat from the warm air, and turns it into a high-pressure gas. As the warm air from your house blows over the evaporator coils, it becomes cool, and is delivered back to the house through vents/diffusers in the ceiling.
  2. Compressor: the high-pressure refrigerant gas flows through to the compressor in the outdoor unit. The compressor pressurises the gas, which condenses it into a liquid.
  3. Condenser: the liquid flows through to the condenser’s coils, also in the outdoor unit. A fan blows over the coils, which dissipates some of the heat from the liquid refrigerant inside. The liquid then passes through an expansion valve, which depressurises and cools it even more, before being passed back to the evaporator to repeat the cycle.

Other notable components of a ducted air conditioning system include:

  • The return air grille: this is where air is pulled into your home.
  • Filter: the filter is located in the return air grille, and helps to filter dust, dirt, and other pollutants.
  • Thermostat: the thermostat (or sensor) measures the temperature of the area being conditioned, allowing the system to adjust if necessary.
  • Controllers: controllers are where you adjust the system, and are usually mounted on the wall. If you have a ducted air conditioning system with smart features, you can control the system from other devices such as your phone, tablet, or laptop.

What are zones in a ducted air conditioning system?

Ducted air con is a type of central air conditioning that uses ducts to channel air throughout the system. With the use of ducts, the system is able to reach different areas of the home, which are called zones. In a larger property, you might have four different zones—one for the main living area, one for the kitchen, one for the master bedroom, and one for a smaller bedroom.

What is ducted reverse cycle air conditioning?

Ducted reverse cycle air conditioners are able to reverse the refrigeration cycle, which allows them to both cool and heat a property. When the refrigeration cycle is reversed, the condenser becomes an evaporator, and cool air is pulled into the system and converted to heat. Most modern ducted air conditioners have reverse cycle capability.

What is a ducted inverter air conditioner?

Inverter technology allows an air conditioner’s compressor to change speed. In older air conditioning systems, the compressor has two modes—on, or off.  When the compressor is on, it goes at full speed until the desired temperature is reached, and then switches itself off. With inverter technology, the compressor is able to change its speed, allowing it to pump the appropriate amount of refrigerant through the system (rather than going at full pelt). This makes it up to 30% more efficient.

What’s the difference between ducted air conditioning and split system air conditioning?

Ducted air conditioning and split system air conditioning both use refrigerated cooling to control a building’s climate. The main difference is that ducted systems use flexible ducting to circulate and distribute air, whereas split systems use wall-mounted units that pump air directly into the room.

Ducted systems tend to be more suited to larger properties, where multiple areas are being cooled or heated. Split systems are generally recommended if you’re trying to cool just one or two rooms, which you want to set the temperature for independently.

Where do the units of a ducted system go?

The indoor unit of a ducted system is usually installed in the ceiling cavity, but it can sometimes be installed underneath the floor (if there’s enough room).

The outdoor unit is placed outside. It releases warm air from the system, and also contains a fan (which can be a little noisy), so tends to be placed away from any living space.