Air Conditioning Systems

There are a number of different types of air conditioning systems used to cool buildings of various sizes and in this article, I explain the main 4 types and how they are used.

Each type has its own pros and cons and depending on how it is deployed, will provide a suitable cooling solution for a given circumstance during hot weather.

This guide will help you find the right place to start when you're trying to buy an air conditioner and explain the differences between the various types.

Common Air Conditioning Solutions

The most common types of air conditioning solutions include self-contained units such as portable, window and PTAC, wall-hung split units and larger central air systems.

air conditioning systemsEvery air conditioner is different in terms of its quality and features, even within the same class.

The efficiency of a modern multi head split unit, which is more energy efficient, could be higher than an older system.

Therefore, it is crucial to examine every model.

The energy rating stars system is a great tool to help you compare the energy usage of air conditioners.

Self Contained Air Conditioners

Self contained AC units are those that perform the entire task of conditioning and cooling the air in a single unit.

These coolers use through wall or window outlets to exhaust the hot air that is produced by the mechanical components during the cooling operation. The main variations of this type of cooler are portable, PTAC and window AC.

Portable Air Conditioners

The portable air conditioners are very easy to transport, but while they are moveable on wheels, they are not necessarily as ″portable″ nor do they weight as little as the name suggests.

Portable air conditioners are designed to be moved around the house from room to room to satisfy the cooling needs of occupants that move around the house for various reasons.

These units are limited in their portability by their need to have their exhaust hose connected to an outlet vent, usually vented in a window opening via a specially designed fixing kit.

These systems cool warm air by cooling it down and then returning it to its original temperature. There are two main types: single and dual hose AC.

Single ducted units are designed to draw warm air from inside the room, cool it and distribute the cool air in the room while venting the hot air outside through its vent hose.

This causes negative pressure in the space, and can potentially draw in warm outside air through cracks in window frames etc. Single-hose portable models are regarded as the most energy inefficient of all types of AC.

Dual hose (and self-evaporating) portable AC units are fitted with a second vent tube that is used to draw outside air into the unit to be cooled. This reduces the negative pressure issues that single duct models can have.

Double hose models can be slightly more efficient than single-hose types.

The main advantage of a portable air conditioner is the lower purchase cost when compared to other coolers. While they may be more affordable upfront, you will end up paying more for electricity.

It's a good idea to look at other types of cooling model especially if you don't plan to move often, have a larger cooling space, or use the unit frequently.


Package terminal air conditioners (PTAC and vertical terminal air conditioners (VTAC) are a less commonly seen style of cooling device in homes, but do feature more commonly in hotel/motel rooms, some offices and hospitals.

These self-contained units perform the cooling process inside a single unit and vent the hot air out through a wall vent.

They are generally installed against an exterior wall for ease of venting and unlike window units, do not obstruct a window opening. This makes them a preferred option when natural light is important for a room.

VTAC units are especially favored in smaller rooms where their vertical orientation allows them to be installed in concealed narrow closets without taking up much floor space.

Window Air Conditioners

These were an old choice for controlling temperature in small rooms. These units include the compressor, condenser as well the coils and evaporator in one unit.

Window air conditioners fit easily into a window. Wall units are similar to window units, but require a hole in the wall to allow them to fit.

Window air conditioners usually have a low initial cost. You might consider using a split or central ducted system to cool multiple rooms.

They are generally more efficient than portable AC models and are best suited to cooling single rooms.

While being fixed in a window space, window air conditioners can be transported with you when you move houses with minimal work as they are generally fitted into window frames with a mounting frame that allows them to slide in and out fairly easily. This makes them ideal for renters or anyone who is thinking of moving soon.

Window air conditioners run in cycles. First, they turn on to heat up or cool down the room and then turn off when the desired temperature has been reached.

They turn on again once the room has warmed up or cooled down. They aren't very efficient at consuming energy.

Split Air Conditioners

Modern homes are often fitted with ductless, split systems that are comprised of two units; the cooling unit that is located inside the home (usually mounted high on a wall) and the condenser unit that is located outside.

They can heat or cool one area or can be set up to control multiple zones. This unit has one compressor, but several indoor units to cool and heat the air.

The indoor units will be installed high on your walls. Therefore, it is important that you consider them when designing the space.

Multi head and wall split systems have a smaller footprint than ductless systems. They are also connected using piping and not large ducts. Despite this, indoor units are still much more visible than ductless system vents.

Although multi-head and wall-hung split systems can be more costly than ducted air conditioning, upfront costs are lower than for the first two types. They tend to be cheaper than portable units or window units, even though they are more expensive at first.

The installation of a wall-hung split, or multi-head split system will require minor modifications to the home, such as holes for the pipe. Professionals can install mini-splits to maximize the benefits of your system.

Central Heating and Air Conditioning (HVAC)

Central air conditioning or ductless conditioning can be more efficient than other types of air conditioning and is generally comprised of a heating and cooling system located centrally in the home.

A ducted central system has a large compressor located outside, an internal evaporative and ducts which bring the conditioned air into various rooms through vents. Ducted systems can require major modifications to your house and are expensive upfront.

These systems are excellent for controlling the temperature inside a home or office. In many cases, they are cheaper to install than multiple mini-splits and window units.

These systems require a large compressor to operate from the outside. However, they are nearly invisible inside due to the vents and controls.

Summary: The Many Types of Air Conditioning System

As you can see from the above, air conditioning systems come in a number of different forms and are best used in a number of different circumstances.

Whether you need to cool a large commercial building or family home, a small suite of offices or a moderate house, or just a small apartment or garden shed home office, there is a cooling solution to fit your needs.