Sign in or sign up

No Bunnings account? Sign up

Project list

Sign in to your account

White kitchen with stainless steel appliances and overhead air conditioning unit
Our guide helps you cut through the jargon so you can choose the right heat pump or air conditioner for your home.


Types of air conditioners and heat pumps

Portable air conditioners can be plugged straight into the mains and positioned in any room or household area where they are needed. All that is required is a nearby window or other opening where the hot exhaust air can be vented to the outdoors via a supplied hose. This is a good portable ‘plug and play’ option for people who are renting, as it is perfect for small spaces and doesn’t involve any structural modifications to the home.

Split system air conditioners are the most popular installation-type units and a great option for keeping comfortable in both summer and winter. With the split system format, the compressor is positioned outdoors and connected by insulated pipes to the head unit inside. The air conditioner head is the component that circulates the air in the room to cool it, heat it (if it’s a reverse cycle model) or change its humidity level.

Window/wall mounted units are all-in-one appliances that are installed into a permanent opening in a wall or window. This is a simple and cost-effective option that tends to be cooling-only (see below), and is normally easier to install than a split-system unit.

Cooling only refers to air conditioners that cannot be switched to heating mode.

Reverse cycle air conditioners can be used for heating as well as cooling. In heating mode, the refrigerant (a chemical used to ‘dump’ heat from inside to outside when the appliance is in cooling mode) is used to extract heat energy from outdoors. The warmed refrigerant is then pumped through the head unit indoors, which circulates air around it and propels the warmth into the room using a fan.

What size air conditioner do I need?

There are many factors to consider when choosing the best air conditioner for your space, so the final appraisal should be made by a qualified professional. We can supply you with a measure and quote as part of our heat pump installation service that we offer to customers buying a Carrier heat pump.

However, for budgeting and to narrow down your selection, it is useful to have a rough idea of what size you will need. Simplified power estimates do not take into account factors such as how well insulated the space is, ceiling height, number of north-facing windows, and so on. 

As a rule of thumb, a small room of roughly 25 square metres will require an air conditioner of about 3kW, while a larger room of 40–50 square metres will require a unit of at least 6–7kW.

Tip: To calculate the area of your room in square metres, multiply its length by its width.

Styled living room featuring an air conditioner, beige sofa, timber coffee table and console

Air conditioner and heat pump running costs

How much an air conditioner or heat pump will cost to cool or heat your home will depend to a large extent on its capacity in kilowatts, but the equation is not as simple as ‘more power equals more cost’. The efficiency of the unit you choose will also have a major influence, and the rating sticker on the appliance will show this, as well as its energy star rating. 

For an accurate idea of one air conditioner’s running cost compared to another, check how many kilowatt hours (kWh) it is estimated to consume per year, as listed on its rating sticker.

What does BTU mean?

You may see an air conditioner’s output listed in terms of BTU, which stands for British thermal units. This is an imperial measurement that indicates an air conditioner’s ability to change the temperature of the air in a room.

How to reduce your bills

When the weather turns cold, running your air conditioner in reverse cycle mode is an excellent energy-saving feature, as it is one of the cheapest ways to heat your home. This is because even when it is very cold outside, the unit can extract warmth from the air using less electrical power than the heat energy it produces.

Air conditioner extras

Allergen filters on most air conditioners capture and eliminate bacteria, fungal spores and dust particles from the air.

Auto-clean options on some models actually wash dirt and grime off internal components inside the head unit for you.

Wi-Fi connectivity means you can control your air conditioner via a smart home system such as Grid Connect, Amazon Alexa or Google Home, and use your smartphone as the remote control.

Timer functions and sleep mode are popular features that let you set when the air conditioner turns itself on, and switches it to a low-power mode while you sleep.

Long reach or long distance airflow on more powerful air conditioners propels cool or warm air up to 18m into an indoor space. This gives you effective temperature control even in very large open-plan areas.

Close up of a person's hand remote-controlling the thermostat of a smart air-conditioner in a living room

More tips for regulating the temperature in your home year-round

Check out tips for winter-proofing your home, five ways to reduce your cooling bills, and our wide range of air conditioners and heat pumps.


Photo credit: Getty Images


Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer. You can also use a simple test kit from Bunnings to indicate the presence of lead-based paint.