A Buyer’s Guide to Air Conditioners

There’s a lot to think about when you decide to buy an air conditioner for your home or office and choosing the right one can be challenging at best. Things to consider include the size, the initial cost and how expensive it will be to install and to run, as well as the noise factor. Then there’s the type of ac, be that split system, reverse cycle, or ducted.

Because the split system type is Australia’s most popular ac, our following guide will focus mainly on these, but the others do get a look-in. If you are considering which type of ac to buy, you will need to acquaint yourself with the types of air conditioners available and know what they do and what they don’t do.

Air Conditioner Types

• Split system: Used mainly to cool large areas – to 60 sqm and they come with an indoor unit connected by pipes and an outdoor compressor unit. They range in price from $600 to $5,500.
• Multi-split: These are a kind of split system, with two or more units placed inside the home linked to an outdoor unit. If a ducted system or separate split systems aren’t an option due to limited space, a multi split system can be a successful way of cooling or heating up to three rooms that are close to each other. Price unavailable.
• Ducted: For controlling the temperature in all areas of a large home, ducted is the best choice. This type of ac has ducts linked to sensors and air outlets in each room and they’re connected to a central unit with a control panel which has settings for the temperatures and the areas of the house that are to be cooled or heated. They range in price from $5,000.
• Window-Wall: These units can cool open-plan areas and rooms up to 50 sqm and are usually installed on an outside wall or in a window. The larger models need to be wired in but the smaller ones can be plugged into a household power point. There aren’t many of these air conditioners on the market these days since most people prefer split systems. The price ranges from $400–$1100.

An Inverter or not?

Once you’ve decided on which general kind of air conditioner will suit you, the next step is deciding whether you want cooling only, or both cooling and heating, and do you need an inverter?

• Why an Inverter?: The speed of the compressor varies on inverters, which means in the outdoor unit it doesn’t need to continuously turn on and off. It simply speeds up or slows as the need requires. This causes less compressor stress and it uses less power because it doesn’t need to start and stop throughout the day or night. This makes these air conditioners cheaper to run and also more efficient. Most split systems sold these days are inverters. Another good point is they can keep within a narrow temperature range.
• And a non-inverter?: These models, which are also known as conventional ac, have the compressor in the outside unit either turned on full, or they’re turned off. Because the compressor turns off and on, rather than slowing down like the inverter models, it causes more wear and tear and also uses much more power. This makes them not as efficient and also more expensive to run, but they are cheaper to buy.
• Reverse-cycle: These ac models are used for heating in winter and cooling in summer, and while they are expensive to buy and install, the heating is cheaper and they’re amongst the most efficient and cost effective ways to heat and cool your house in the long run.
• Cooling-only: If you live in a climate of mild winters and need the cooling for summer or if you have a heating system already, then a cooling-only ac might be the best option for you. They are usually less expensive to run than reverse-cycle models and usually come equipped with the same features. An inverter reverse-cycle split-system ac is normally the best way to go for most homes.

The different kinds of indoor air conditioner units

• High wall: This is where the air conditioner unit is mounted indoors high up on a wall – it’s the usual place for a split-system. The air easily flows over a room and since hot air rises, the cool air will sink and the hot air is pushed up and floats away.
• Cassette: The indoor unit here is mounted in the ceiling but some models can be mounted on the floor or either on the floor or in the ceiling.
  Floor-mounted: The unit is wall mounted but low down on the floor, which means it could be a more suitable model for some rooms and better still if it’s main use is for heating. The heated air will rise to the ceiling, heating the whole room.

Choosing the most suitable capacity (size)

Air conditioner capacity is measured in kilowatts (kW) with smaller rooms possibly needing a 2.5kW model, and a larger room or open-plan space could require 6kW or even more. Accuracy when calculating the needed heating or cooling capacity of an ac is important. You can get an oversimplified calculation online and some installers aren’t much better at judging how much you will need. So to get a better idea of your needs it’s best to take the details of the room into account. For example:

1. The local climate
2. The kind of room, whether it’s a kitchen, bathroom, bedroom etc.
3. The room’s size including its width and length and the height of the ceilings.
4. A large north or west-facing window will usually allow a lot of heat in summer, so the orientation and the size of glass doors and windows have to be taken into account.
5. The size and orientation of the windows and glass doors.
6. Is there wall, ceiling and floor insulation?
7. Are there heavy curtains on the windows or any shading effects?

There’s a good calculator on the Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH) website at http://www.fairair.com.au/Calculator.Size.aspx.

How much will my air conditioner cost to run?

In the average Australian home, heating and cooling accounts for some 40 percent of the energy used. But there are things you can do to keep the running costs of your ac down.

• Having the right size of ac is vital.
• Models with star ratings that are high will use less power and also be more efficient than those with fewer stars on the label.
• Try to make your home an energy efficient one.
• Switch to eco mode if your unit has one.
• When setting the temperature on your ac, make it reasonable so you don’t put too much pressure on the system.

What is a reasonable temperature?

If the day is hot, say 30°C you might think the temperature on your ac should be set at 20°C but even though you might think it’s counterintuitive, it’s best to set it at 25°C. This will save wear and tear on the unit and also save you money. For every degree hotter or cooler, you add about 10 per cent in running costs.

Dehumidify and dry modes

Too much dampness in a home can be a problem and if you have that problem a dehumidifier might solve it, and air conditioners are good at controlling warm, humid air. When in cooling mode, they remove some moisture from the air.

What about noise?

Nobody wants a noisy ac that interferes with their activities or those of their neighbours. Many local councils have ac noise restrictions, so it’s best to check the regulations and also check the noise levels which should be shown on the labels on the ac you consider buying. Noise is measured in decibels (dBA) adjusted to reflect how the ear responds to different sound frequencies. The noise level range for indoor air conditioners is from 20 to 30 dBA and that’s on the lowest setting of the fan. And at the highest speed, it’s up to 40 to 50 dBA. Levels for outdoor air conditioning units are usually in the range of 45 to 65 dBA.

To help you compare them:

• 60 dBA: Is a normal conversation level
• 30 dBA: The sound level of a quiet home
• 50 dBA: Inside a quiet car while driving
• 70-80 dBA: A typical vacuum cleaner
• 145 dBA: Firecracker