Split System Air Conditioner: What is it, Types, Working principle and Pros and Cons
Get a Quote
A split system air conditioner is a type of air conditioning system that has an outdoor condenser unit and an indoor evaporator unit connected by refrigerant pipes. The term "split" refers to the two separate units.
Split systems are capable of both heating and cooling (split system heating and cooling). They pump refrigerant between the outdoor and indoor units to transfer heat in or out of a home, allowing you to control the temperature.
Split systems are commonly installed in Australian homes and small commercial spaces like offices and shops. According to the Australian Bureau of Statistics, over 40% of Australian homes have reverse cycle split system air conditioners as of 2021.The main working principle of a split system air conditioner is the refrigeration cycle. The cycle uses a refrigerant that absorbs heat and changes between gas and liquid states. The outdoor unit compresses the refrigerant gas, heating it up. The hot gas then passes into the indoor unit and condenses, releasing its heat. This cools and dehumidifies the air. The cycle then reverses to provide heating.
Key advantages of split system air conditioners are their affordability, efficiency and flexibility compared to other types of air conditioning. As they have separate components, the outdoor unit can be installed out of sight and the indoor unit placed for optimum room cooling. They are also quieter than other types of air conditioning.
Potential disadvantages include heat transfer efficiency loss from the long piping, possibility of refrigerant leaks, and their unsuitability for very large spaces. Professional installation is also recommended.
Split system air conditioner costs vary greatly depending on the unit size, features and brand. As a guide, a popular 2.5kW reverse cycle split system unit from a leading brand costs approximately A$1,100 to purchase plus A$880 for installation. Owners should budget for annual servicing and cleaning which may cost around A$220 per service.
What is a split system air conditioner?
A split system air conditioner is a type of air conditioning system consisting of an outdoor unit and an indoor unit connected by refrigerant piping and electrical cables. The term "split" refers to the two separate units. Split systems use the refrigeration cycle to cool and heat the air.
The first split system air conditioner was invented by Stuart Cramer in 1902. His system used fans to blow air over a cold water coil, which was an early form of what would later become modern refrigerant-based air conditioning.
Key components of a split system air conditioner include a compressor and condenser in the outdoor unit, and an evaporator and blower fan in the indoor unit. The two units are linked by copper pipes that allow refrigerant to flow between them.
What is a split system AC unit?
The term "unit" refers to each individual component that makes up the split system. This includes both the outdoor unit and the indoor unit.
The outdoor unit houses the compressor, condenser coil and fan. It is installed outside the home, usually on the ground or mounted on an exterior wall. The indoor unit contains the evaporator coil and blower fan, and is mounted high up on an interior wall or ceiling.
Different types of indoor units are available depending on the application, such as wall-mounted, ceiling cassette, and ducted units. The installer will determine the optimal indoor unit type based on room size, aesthetics and installation considerations.
Who invented the split system air conditioner?
In the history of air conditioning, the basic concept of the split system can be traced back to the 1902 invention of Stuart Cramer. However, the modern refrigerant-based split system air conditioner was invented later in the 20th century.
Specifically, the split system design allowing separate indoor and outdoor units was patented in 1935 by two Brazilian engineering students, Edson Giunta and Eduardo Kneese de Melo. Their system design enabled air conditioning units to be less intrusive indoors by locating the noisy mechanical components in a separate outdoor unit.
This pioneering split system design by Giunta and Kneese de Melo paved the way for the split system air conditioners widely used for residential heating and cooling today.
How does a split system air conditioner work?
Split system air conditioners work by transferring heat between the inside and outside air. This is accomplished through the refrigeration cycle using special refrigerants and a compressor to control air temperature.
To provide cooling, the split system air conditioner goes through a 4-step process:
- Refrigerant in the indoor unit absorbs heat from the air in the room, causing the refrigerant to evaporate into a gas. This evaporation has a cooling effect.
- The gaseous refrigerant is then compressed by the electric compressor located in the outdoor unit. When compressed rapidly, the refrigerant heats up significantly.
- The hot gas passes through the outdoor coil (condenser), where a fan blows outdoor air though the coil. This allows the hot refrigerant gas to dissipate its heat into the outside air, causing the gas to condense back into a high pressure liquid.
- This liquid refrigerant then passes through an expansion valve in the indoor unit, causing it to turn into a cold, low pressure mixture of liquid and gas. It once again absorbs heat from the indoor air via the evaporator coil, providing cool air circulation into the room via the indoor blower fan. Any accumulated moisture also condenses and drains out.
The most common refrigerant used in split system air conditioners is R410A and R32.
To provide heating, the process is reversed:
- The liquid refrigerant in the outdoor unit absorbs heat from the external air, causing it to evaporate.
- The refrigerant gas is compressed, increasing its temperature.
- The hot gas dissipates its heat indoors via the indoor coil, heating the air.
- It condenses back into a liquid, flowing outside to repeat the cycle.
The cooling and heating capacity depends on the power and size of the indoor and outdoor units.
- Small split systems under 2kw-5kwkW capacity
- Large split systems 5kw to 10kW+ capacity
- Multi-split systems with multiple indoor units connected to one outdoor unit
The power is denoted in the model description, for example a "Mitsubishi 5kW split system air conditioner model is MSZ-AP50VGD-2".
What are the split system air conditioner components?
The components of a split system air conditioner refers to the individual working parts located in either the indoor or outdoor units. They each serve specific functions that enable the heating and cooling process to take place.
The main indoor components are:
- Evaporator Coil - A long copper tube filled with refrigerant to absorb heat from the indoor air. This causes the refrigerant to evaporate and cool the air.
- Blower Fan - Circulates the indoor air over the cold evaporator coil then drives the colder air into the rooms through vents and ducts. Essential for efficient circulation.
- Filter - Traps dust, dirt and debris to keep the coil surfaces clean for optimal performance. Needs regular cleaning or replacing.
The main indoor components are:
- Compressor - Raises the temperature and pressure of the refrigerant gas for circulation between indoor and outdoor units. The heart of the split system operation.
- Condenser Coil - Refrigerant from compressor dissipates heat here, condensing the gas into liquid form to repeat the cooling cycle.
- Outdoor Fan - Draws outside air over the hot condenser coil to cool the refrigerant, while blowing out hot exhaust air.
- Expansion Valve - Drops the liquid refrigerant to a lower pressure to resume absorption of indoor heat when it passes back into the evaporator.
Proper functioning of all these components is crucial for effective and reliable split system heating and cooling.
What are the split system air conditioner types?
There are 3 main types of split system air conditioners: standard split systems, mini split systems and multi-split systems.
A standard split system has one indoor unit connected to one outdoor unit, and is the most common type used in homes.
A mini split system has a smaller, more compact indoor unit for smaller spaces. The outdoor unit is similar in size to standard systems.
A multi-split system has a single outdoor unit linked to multiple indoor units, allowing different rooms to be air conditioned using just the one external compressor. Useful for zones.
Commercially, split systems are often described by the kilowatt (kW) power or capacity of the indoor unit. The kW indicates the potential rate of cooling or heating energy transfer.
Tips for selecting the right air conditioning system:
- 2.5kW small split system air conditioner for bedrooms
- 5kW split system air conditioner for small living rooms
- 8kW large split system for larger living rooms
It's important to choose the correctly sized system for your space. An underpowered system will have to work harder, while an oversized unit is less efficient and has higher operating costs. Getting professional advice is recommended. An inaccurate system sizing can lead to issues with temperature, humidity, mould formation from condensation and higher energy bills.
What is a Ductless Mini-Split System?
A ductless mini-split system is a compact, energy efficient type of split system used where installing ductwork is impractical. It consists of an outdoor compressor/condenser and one or more small indoor wall-mounted or ceiling units.
The main advantages of ductless mini-split systems are:
- Their small, discreet indoor units allow installation where standard split system vents or ducts aren't feasible
- Useful for heating and cooling additions like garages or attic conversions
- Separate temperature control possible in different rooms
- Quieter operation than central ducted systems
- Increased home resale value by air conditioning previously unventilated areas
What is a Multi-Split System?
A multi-split system connects multiple indoor units to one outdoor unit. It enables several rooms to be air conditioned using a single exterior condenser by utilising a branched network of refrigerant piping.
Key advantages of multi-split air conditioner systems include:
- Avoiding multiple outdoor units in residential blocks for aesthetic reasons
- Centralised control of rooms with differing heating/cooling needs
- Cost savings on installation due to shared infrastructure
- Adjusting capacity by the addition or removal of indoor fan coil units
- Ideal for two-storey homes due to flexible configuration
Multi-split systems are the preferred ductless heating & cooling solution for larger homes or office spaces. Their expandable nature makes them a versatile choice.
How to choose the size of split air conditioner
Follow these key steps to choose the correctly sized split system:
Step 1: Calculate the floor area of the room in square metres
Step 2: Multiply the area by the power required per square metre, which is around .13kw per sqm for Australian homes
Step 3: Select a system with higher capacity if the room gets a lot of sun or has a high occupancy
Step 4: Consider 2 smaller systems for large spaces rather than 1 oversized unit
Step 5: Have an OZ Air Group Air Conditioning specialist confirm your estimated size
An accurate calculation matching usage needs is important for efficiency. Over or undersized units can cause problems.
What are the Benefits of Installing split system air conditioners?
An accurate calculation matching usage needs is important for efficiency. Over or undersized units can cause problems.
- Increase home comfort by regulating room temperatures
- Improve air quality and circulation with built-in filtration
- Enhance lifestyle enjoyment of spaces like lounges or bedrooms
- Provide simultaneous heating and cooling to different zones
- Achieve cost savings compared to running inefficient portable units
- Increase convenience with easy operating conditions from a compact indoor unit
- Improve resale potential due to ductless flexibility and modern reputation
With multiple performance and lifestyle benefits, adding split system air conditioning is a smart way to upgrade a home.
What is the noise level (dB) on a split system air conditioner?
The noise level refers to the sound power or loudness emitted from the indoor and outdoor units of a split system, measured in A-weighted decibels (dBA). This equates to how noises appear to the human ear.
On average, most split systems produce between 30 to 60 dBA from the outdoor unit and 20 to 40 dBA from the indoor unit during operation. Top brands such as Daikin, Fujitsu, Panasonic, and Mitsubishi Electric have compressor technologies that lower outdoor noise levels to as low as 46 dBA even at high capacity.
Indoor units are noticeably quieter as they contain only the evaporator fan and air distribution louvres. Here sound levels range from faint background noise of 20dBA for some wall mounts, up to around 39dBA for more powerful ceiling cassettes on their highest fan setting.
When selecting split systems, noise is an important factor especially for outdoor units placed near windows and entertainment areas. Models from reputable brands generally have a sound power that does not interfere too greatly during use - but checking specifications or consulting experts is advised for noise sensitive installations.
What are the Cons of Installing split system air conditioners?
Disadvantages of installing split system air conditioners include:
- Increase energy bills from daily running costs
- Require professional installation leading to higher initial cost
- Possibility of leakage of refrigerant gases over time
- Chance of mechanical breakdowns requiring repair by a tradesman
- Can detract from a room's aesthetic if large wall or ceiling units
- Outdoor units may disturb neighbouring residences or business areas with noise
While cheaper to install than central systems, split air conditioners can raise maintenance requirements and monthly expenses in the long run. Weighing up these cons is important when making a decision.
Are split system air conditioners good for residential homes?
Yes, installing split system air conditioning units is a good choice for most Melbourne homes. Split systems are well suited to residential spaces thanks to advancements making them powerful enough even for our hot summers, yet energy efficient and quiet.
Benefits for households include zones control, no major ductwork alterations needed, and flexible installation options. For larger homes a multi-split system or multiple smaller units can be used to avoid a bulky central system.
For commercial buildings with open spaces though, ducted or central systems may be preferable. The multiple vents and zoning control help modify conditions for workspaces or high occupancy levels, despite higher install costs. But for most homes, a quality split system is hard to beat.
Is a split system air conditioner good for bedrooms?
Yes, a split system air conditioner is a good option for cooling or heating a bedroom. Their adjustable temperature controls and quiet operation make split system units ideal for rooms where sleep and noise considerations are a factor.
Advantages for bedrooms include allowing desired temperatures to be set at the press of a button, such as creating cooler conditions overnight during Melbourne's hot humid nights. Their ductless, discreet wall mounting keeps rooms visually tidy. Some even have a Sleep Mode optimised for soundless running without disturbing sleep.
Is a split system air conditioner good for commercial buildings?
For commercial spaces, split systems may not be the most suitable form of air conditioning in all cases. The main downside is that while split systems serve individual rooms well, larger warehouses or open floor offices often favour other types of systems.
The better alternative option for many commercial premises is installing a multi-zone ducted system. Ducted systems have the advantage of providing even cooling or heating to expansive floor spaces through multiple ceiling vents. Though they require major ductwork construction initially, the zoned climate control suits businesses with high occupancy levels or rooms with machines generating excess heat. This makes them preferable for maximising commercial workplace comfort.
So some small offices may install split systems successfully, while noise levels and congested ceiling spaces in others clearly favour ducted systems instead. The intended business use of the buildings drives optimal system selection.
Is split system air conditioner good for Melbourne climate?
Yes, a split system air conditioner is an excellent choice for the varied climate in Melbourne. During hot summers with temperatures over 30°C, their powerful and adjustable cooling keeps homes comfortable. Split systems also work as effective heaters in winter when overnight temperatures drop below 10°C.
Most quality split systems perform very well across Melbourne's temperature extremes. Features like inverter technologies help them operate efficiently year-round, without drastically spiking power bills in summer or winter. With good insulation, sealants, window coverings and a suitable-sized unit, modern split systems can handle Melbourne's demands.
What is the best split system air conditioner brand in Australia?
According to reviews and industry surveys, the top split system air conditioner brands in Australia provide an optimal mix of reliability, features and value for money:
- Daikin - over 20% market share. Excellent warranty and tech.
- Mitsubishi Electric - innovative, quiet technology.
- HItachi - reputable Japanese brand, self cleaning options.
- Chance of mechanical breakdowns requiring repair by a tradesman
- Fujitsu - reliable, energy efficient heating and cooling performance.
- Mitsubishi Heavy Industries - popular for modern designs and strong after-sales support.
While there are lower cost brands too, these companies consistently offer robust units with great customer satisfaction for Australian conditions. Weighing up professional advice for your home alongside cost finds the best brand fit.
How much does a split system air conditioner cost? (Purchase cost only)
.jpeg)
The cost to purchase a split system air conditioner can vary greatly depending on the size, brand, type and features. However, as a general guide for a good quality residential unit from a leading supplier:
- The cost to purchase a 2.5kW-5kW split system unit ranges from AUD $600 up to about AUD $1,800
- Larger capacity split systems between 5kW to 8kW cost approximately AUD $1,500 to AUD $5000
- Advanced multi-split systems come in from AUD $2,500 up to AUD $10,000+
The cost to install a split system also depends on the complexity and whether it is a new installation or a replacement job.
- Basic installation starts from around AUD $800 for a wall mounted unit, up to $2500+ for more difficult jobs
Ongoing costs come from:
- Annual services & maintenance which cost about AUD $220-$500
- Energy bills - running an efficient 5kW system for 6 hours per day all year can cost AUD $800+ annually
While split systems may require a notable upfront investment, you can find good home & budget models if you research brands, efficiency ratings and installer deals available in your area.
If seeking a cheaper split system air conditioner, some entry-level brands to consider are:
- Kelvinator - Basic features & performance for lower purchase costs
- Midea - Affordable Chinese brand with good warranty support
- Teco - Well-priced units adequate for smaller spaces
Going for a discounted or cheap split system unit can work out if less frequent usage is needed. But it's recommended to check the energy efficiency ratings, as less durable parts may cost you more over time. Getting professional advice also ensures your unit meets budget and functional needs. Regular maintenance ensures optimum performance for many years.
How much does it cost to install a split system air conditioner?
The average cost to install a split system air conditioner in Australia is between $800 - $2500 depending on the complexity of the job. In Melbourne, most standard 2.5kW split system installation costs range from $800 for a basic wall mounted unit, up to about $1500+ for more tricky installations.
Factors affecting installation costs include:
- Need for additional cabling, piping, valves or wiring
- Single or multi-split system configuration
- Inclusions like outlets, safety switches or touchscreen controllers
- Location of the indoor and outdoor units and difficulty of mounting
Here at Oz Air Group, we offer professional split system installation services across Melbourne and suburbs starting from $800 with a 5 year warranty on workmanship. Get in touch if your home or office needs a split system installed.
What is the warranty period of a split system air conditioner?
Most leading split system air conditioner brands offer warranties of 5 years for residential systems, covering parts and labour on the compressor and other components. Budget models may only offer the legally required 3 year warranty in Australia.
Warranty periods can vary based on:
- Reputability and reliability of the brand
- Type of system, commercial vs home units
- Whether an extended warranty is purchased
Does a split system air conditioner require maintenance?
Yes, it is recommended to perform regular servicing and maintenance on split system air conditioning units. Both the indoor and outdoor components accumulate dust, debris and mould over time which can degrade performance or functionality if not cleaned.
For indoor unit maintenance:
- Check and clear drain lines for condensation flow
- Use a disinfectant spray on fan coils and catchment trays
- Ensure unobstructed air flow at inlet and outlet vents
- Clean or change air filters monthly
For outdoor unit maintenance:
- Clear leaves or debris from around external unit
- Hose down condenser coils to remove dirt buildup
- Trim back foliage blocking airflow intakes
- Verify refrigerant levels and top up if required
- Check fan blades and condenser wiring
Following this split system maintenance routine avoids issues and keeps cooling and heating running optimally.
How to Maintain split system air conditioner Units
The split system units refer to the air conditioner’s separate indoor and outdoor components. The indoor unit consists of the evaporator coil, filters, drain pan and blower fan. The outdoor unit contains the compressor, condenser coil and an external fan.
Follow this routine maintenance checklist for your split system's indoor and outdoor units:
- Step 1: Clean air filters monthly by vacuuming debris and washing filters
- Step 2: Use a garden hose on a low setting to clear dust from outdoor unit coils and fan
- Step 3: Cut back foliage or structures obstructing airflow around external unit
- Step 4: Bookend of financial year professional services to disinfect, optimise and identify faults
Letting dust and debris accumulate by neglecting maintenance causes air flow issues and failures. So remember to care for both units!
How long does a split system air conditioner last?
The average lifespan of a split system air conditioner is 8 to 12 years. Units that are well-maintained with annual servicing, cleaning and part replacements as required, can potentially operate reliably for over 15 years.
Factors impacting lifespan include brand quality, usage levels, installation quality and ongoing maintenance. Higher-end brands from Daikin, Fujitsu or Panasonic will generally outlast cheaper models.
Following professional care guidelines means your split system should provide many years of effective climate control. If your old unit is playing up, get in touch about a replacement split system - many come with over a decade manufacturer's warranty.
What are the alternatives to split system air conditioners?
The main alternative air conditioning system types are:
- Ducted systems - Better for large, open floor spaces across multiple zones
- Evaporative coolers - More affordable to install and run, suit low humidity areas
- Portable units - Offer flexible placement but are less energy efficient
What is the difference between split AC and inverter AC?
The main difference between a split AC and inverter AC is that standard split ACs have fixed speed compressors that fully switch on or off to regulate temperature. Meanwhile, inverter split ACs have variable speed compressors that continually adjust output to more precisely match the cooling or heating demand needed.
Inverter air conditioner benefits include higher year-round efficiency, quicker room temperature pull-down, quieter operation, and more granular control for comfort. This makes inverter-based split systems ideal for living spaces.
In terms of installation, there is no major difference - standard and inverter split systems have similar indoor and outdoor units connected by piping and cables. The only distinction is that an inverter AC will require an inverter drive to be wired to the outdoor unit.
What is the difference between split AC and window AC?
The main difference is that window AC units are single self-contained systems designed for mounting in windows to service one room. Split AC systems have separate, connected indoor and outdoor units for more flexible installation, zoning and higher whole home cooling capacity.
Split systems offer greater energy efficiency, power, smart features and longevity compared to window units. But window systems take up less internal space and have lower install costs. This makes them preferred for small rooms.
Regarding installation, the key difference is that window ACs are fully integrated systems designed for simple window mounting to service a single room. Split ACs require indoor and outdoor unit installations, with the outdoor unit often wall mounted or placed on concrete slabs. This allows split systems to cool multiple rooms. But window ACs just slot into a window frame without the need for major mounting work.
Are split system air conditioners the best solution for Melbourne’s climate?
Yes, split system air conditioners are one of the best air conditioning solutions for coping with Melbourne’s varied climate across the seasons. Their ability to efficiently heat and cool makes them an ideal fit for the city’s hot summers and brisk winters.
For Melbourne homes and apartments, split systems provide reliable and controllable heating and cooling all year round. Features like good timers, energy ratings and zoning capabilities suit the demands of the climate. They remove humidity in summer and provide cosy warmth in winter without excessive energy costs for many households.
Compared to other types of air conditioning like window units or evaporative coolers, split systems offer stronger performance across Melbourne’s climate range. Easy installation also makes them one of the quickest and most effective ways to add climate control. New variable capacity inverter units further improve their climatic suitability.
So for most residential contexts around Melbourne and Victoria, a modern split system air conditioner is hard to beat as an all-purpose heating and cooling solution. They provide the power, features and responsiveness required for living comfortably through harsh summers and cold winters.
.png)