Air Conditioning

What size air conditioner do I need?

Correctly sizing an air conditioner is essential to ensure it delivers the heating and cooling performance you require in your home. The main factors that determine sizing are;

    • The size of the area to be serviced
    • The construction and level of insulation
    • Orientation
    • Window sizes
    • Zoning
  • How the space is used

Contact us and let our system designer help you correctly size a system for your needs.

Running costs

The costs to run an air conditioner are extremely variable and depend on;

    • The efficiency of the unit
    • The design and installation quality
  • How often the unit is operating

Electricity costs have risen significantly over the past few years, so to keep your running costs down it is important to select an efficient Air Conditioning Unit and have it correctly designed and installed. To further reduce your costs, you can install a Solar PV array so on those hot summer days you can use the sun to power your air conditioner.

Legionella risks

The Legionella virus is sometimes found in the cooling towers of industrial chiller systems used on commercial properties. Residential ducted and split systems do not pose a Legionella risk.


Everybody’s home and needs are different so it is difficult to determine the best brand for your particular requirements. That is why we recommend a no obligation home visit from one of our system designers to assist you in selecting the correct product for your needs and budget. Contact us today to get a system help you select the best product for you.


Air Conditioning is a significant investment and it is important to maintain it correctly in order to keep running costs down and extend the life of the unit. For residential installations, an annual service is generally sufficient, however, commercial installations will depend on the installation type and usage levels. We believe in maintenance so strongly that we offer extended warranty on selected systems if you join the NGS maintenance program.

Split systems

A split system consists of an outdoor compressor and a wall mounted indoor unit. This is typically used to heat/cool only one room.

Multi-head splits

Multi-head splits are systems where there is still only one outdoor unit, however, this is connected to 2 or more wall mounted indoor units. Multi head systems allow you to heat and cool more than one room with only one outdoor unit. This is more efficient and also reduces the maintenance costs of the system.

Ducted systems

Ducted air conditioning systems have a compressor outside and a fan unit usually mounted in the roof space. Ducting is then installed from this centralised fan unit to all of the areas that require heating/cooling. Individual areas can also be zoned to reduce operating costs or to focus the heating/cooling power to specific areas.

Digital Scroll

Digital scroll technology is the latest energy efficient technology for air conditioners. This technology delivers significant reduction in energy costs as well as better temperature control and management. They have been proven to be even more efficient than inverter type air conditioners.

What does the term ‘horsepower’ mean in terms of an air conditioner capacity?

The ongoing use of ‘horsepower’ by retailers is of concern to energy regulators in Australia. This term bears no relation to the output capacity of the unit. The only valid capacity measure is the kW output under AS/NZS3823 condition T1 for cooling or H1 for heating. The term ‘horsepower’ came from a time when air conditioner compressors where driven with mechanical motors. The output of an air conditioner depends on the motor efficiency, the compressor efficiency, the evaporator and condenser design and heat transfer properties, relative size of the evaporator and condenser, air flow design over the evaporator and condenser, fan efficiency and size, control system etc. Defining the input or output power of the electric motor in such a system as a proxy for capacity is completely misleading in all cases.
NGS will never try to mislead you by quoting horsepower instead of kilowatts.

How can I easily calculate the size of split system I need?

Here is a simple two-step formula you can use:

    1. Calculate the area of the room.
  1. Multiply the area by 150* watts.

For example, if your room is 6m by 5m:

    1. 6m x 5m = 30 m2
  1. 30 m2 x 150 watts = 4500 watts (4.5Kw)

*It’s also useful for us to know which direction the rooms face. Southerly facing rooms require less cooling in summer but more heating in winter. If the room is facing West, or if it faces North and has large windows, use a factor of 180 watts for your calculation. In our example above, a Westerly facing room would need a 5.4Kw system.

If more than two people regularly occupy the room in daylight hours, add an extra 200 watts for each additional person.

Here’s a helpful hint to keep your running costs down: make sure the external compressor unit is shaded.

What is an inverter air conditioner?

Inverter air conditioners are more economical to operate and quieter to run than conventional units. They can handle wider extremes in temperature, are smoother and more stable in operation and reach the desired temperature more quickly than conventional air conditioners.

How often do I need to change filters?

The standard air clean filter uses static electricity to clean dust and other fine particles such as plant pollen that are too small to see.

Air conditioning filters should be cleaned every three months and ideally they should be cleaned monthly during summer. You should also clean the air vents at the same time. We recommend you make a diary or calendar note at the start of each new year as a reminder.

How much energy does an air conditioner consume?

This depends entirely on the system. We can provide you with relevant information when a decision is reached about which systems are most suitable for you.

How do I dispose of an old air conditioner – can I just dump it?

Unless you have already had the refrigerant professionally recovered from the old unit, no, you should not dump it. This is because the refrigerant gas needs to be destroyed in order to prevent it from leaking into the atmosphere and contributing to global warming.

What is the ideal temperature to set my air conditioner to?

Most people find that a year-round temperature of 23 degrees is acceptable. This is the temperature at which most air conditioners run to the peak efficiency.

How long should I expect my air conditioner to last?

If the unit is the right size for your environment, if you routinely clean the filters and have air vents and have the systems serviced once a year, then you should expect ten years or maybe more. If you join the NGS Maintenance program, we offer extended warranties on selected systems.


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