Types of refrigerated systems

If you prefer a refrigerated air conditioner you have a choice between; a portable unit, window/wall unit (for single rooms), a split system (for single or multiple rooms) and a ducted air conditioning system (to cool your whole house/building).

Portable units:

• Separate indoor and outdoor unit connected by a flexible hose through an open window or external door.
• Plugs into standard power outlet.
• These units tend to be less energy efficient than the alternative refrigerated options below.
• Suitable for: rooms up to 35 m2.
• Purchase cost: $800–$3000.

Window/wall units:

• Require external window or wall.
• Small units can use existing power outlets.
• Larger facia units may require additional wiring.
• Outside coil should be shaded if possible.
• Suitable for: single room cooling up to 60 m2.
• Purchase cost: $500–$1600 plus installation.

Split System and multi split systems:

• A split system requires two units – the compressor/condenser unit (installed outside the home) and an evaporator unit (installed inside the home). These units are connected by a pipe that carries refrigerant. They are usually wall mounted, but can also be floor or ceiling mounted if required.
• When a split system has more than one evaporator connected to the outdoor condenser it is called a multi split system. Multi split systems can provide air conditioning to up to nine rooms, using only the one outdoor unit. This is a good option if you want a multi-room or whole house air conditioning system but do not have enough space for multiple outdoor units or enough ceiling or floor space to install ducted air conditioning. Multi split systems allow you to set different temperatures in different rooms.
• Split systems are ideal where no suitable window or external wall location exists.
• Their indoor operation is very quiet.
• The indoor unit can be located up to 15 metres away from the outdoor unit.
• Suitable for: from single room to whole house cooling.
• Purchase cost: $1000–$10 000 (multi splits) plus installation.

Ducted Air Conditioning:

• Like the split system ducted air conditioning has two components with the compressor/condenser unit installed outside the house. The indoor unit however is located in the ceiling space and the air is distributed through vents around the house.
• Ducted air conditioning can be installed in any home with sufficient ceiling or floor space.
• This type of system is much less visible than a split system, but you cannot set different temperatures in different areas. You can, however, turn on air to one part of your home but not another by creating zones (such as bedrooms or living room).
• Suitable for: Whole house cooling.
• Purchase costs: on average, ducted systems cost anywhere from $6,000 to $12,000 fully installed.

Ducted and split system air conditioners will have either a single speed motor or a variable speed motor. The component that allows a motor to be variable speed is called an inverter. A standard air conditioner with a single speed motor has to switch itself on and off to maintain room temperature. An air conditioner with an inverter can increase and decrease motor speed (and power) to maintain room temperature.

An inverter unit spends much of its time working at part load (i.e. not full power) – this technology saves energy, reduces wear on parts and avoids sharp fluctuations in electricity use.

Your choice between an evaporative or refrigerated air conditioner will depend on your local climate, your personal preference and of course, your budget.