How to Install a Ducted Air Conditioner: What Every Australian Homeowner Needs to Know

How to Install a Ducted Air Conditioner: The Short Answer

Installing a ducted air conditioner is not a DIY project. By law in Australia, ducted air conditioning installation must be carried out by a licensed HVAC technician and a licensed electrician. No amount of YouTube research changes that. If you're asking because you want to understand the process, control costs or check whether your home is a good candidate, you're in the right place. This article covers what ducted air conditioning is and how it works, the full installation process step by step, what makes some jobs more complex than others, what you can expect to pay and whether an older home can realistically have a ducted system fitted.

The short version: get a licensed installer in for an assessment, get at least two quotes and make sure both the HVAC and electrical licences are confirmed before anyone starts work.

What the Ducted Air Conditioning Installation Process Actually Involves

A ducted air conditioning installation is a multi-trade job that typically takes one to three days from start to finish. It involves roof space access, ductwork runs through ceiling cavities, refrigerant line connections and switchboard work. Here is exactly what happens at each stage.

1. Initial home assessment and load calculation. A licensed HVAC technician visits your home to measure the floor area, assess ceiling height, check insulation, count windows and note which direction rooms face. This information feeds into a heat load calculation that determines the correct system capacity. Skipping this step and guessing on size is one of the most common and costly mistakes homeowners make.
2. Choosing the right system size and brand. Based on the load calculation, your installer will recommend a capacity range. For smaller homes or apartments, an 8.5kW unit such as the Fujitsu SET-ARTH30KHTA (priced at $3,604) is a practical starting point. A three or four bedroom home typically suits a 10kW system like the Daikin FDYAN100 at $4,138. Larger homes or open-plan layouts often need a 12.5kW unit such as the Daikin FDYAN125, priced at $4,761. Your installer will also factor in zoning requirements, the number of outlets and whether you want smart controls.
3. Receiving and reviewing a detailed quote. A reputable installer will provide a written quote that itemises the system unit, ductwork, vents, electrical work, any crane or scaffolding hire and the commissioning fee. If a quote is a single lump sum with no breakdown, ask for the detail before signing anything.
4. Scheduling the installation. Most residential ducted installations take one to three days depending on home size, roof space access and the number of zones. Larger homes with complex duct runs or difficult roof access can take longer. Confirm the timeline in writing so you can plan around it.
5. Installation day. This is where the bulk of the work happens. The indoor unit (the air handler) is positioned in the roof space or, in some homes, under the floor. The outdoor compressor unit is placed on a concrete pad or wall bracket outside. Ductwork is run through ceiling cavities to each zone, and vents are cut and fitted in the ceiling of each room. Refrigerant lines are connected between the indoor and outdoor units, and all electrical connections are made to the indoor unit and the zone controller.
6. System commissioning and testing. Once everything is connected, the technician pressurises the refrigerant lines to check for leaks, then charges the system with refrigerant. Each zone is tested individually to confirm airflow, temperature and zone control are all working correctly. This step cannot be rushed and should not be skipped.
7. Handover and user walkthrough. Your installer should walk you through the zone controller, explain how to set temperatures and schedules, and hand over all documentation including the warranty cards and the compliance certificate for the electrical work.

Who Actually Does the Work?

A ducted installation involves at least two licensed trades. The HVAC installer handles the mechanical side: positioning the indoor and outdoor units, running the ductwork, fitting the vents and connecting the refrigerant lines. Handling refrigerant legally requires an ARC (Australian Refrigeration Council) licence. If you want to understand what an ARC licence is and why your installer needs one, it is worth reading up before you sign a quote.

The licensed electrician handles the power supply from your switchboard to the indoor unit and any associated wiring. Some HVAC companies have both trades in-house, which can simplify scheduling and accountability. Others subcontract the electrical work to a separate firm. Either arrangement is fine, but you should confirm both licences before work begins. Ask for the HVAC contractor's ARC licence number and the electrician's licence number. Any reputable installer will provide these without hesitation.

What Makes Ducted Installation More (or Less) Complex?

The difficulty and cost of a ducted air conditioning installation depends heavily on your home's physical characteristics. Two houses with the same floor area can produce quotes that differ by thousands of dollars, simply because one has a generous roof cavity and a modern switchboard while the other has a cramped attic and 1970s wiring. Understanding the main variables helps you have a more informed conversation with your installer and avoid surprises.

The factors that most commonly affect complexity and cost are:

• Roof space access and height. A tall, clear ceiling cavity makes it straightforward to position the indoor unit and run ductwork. A low or heavily obstructed roof space forces technicians to work in tight conditions, which adds time and labour cost.
• Home size and number of zones. More floor area means more ductwork, more outlets and a larger capacity unit. Each additional zone also adds a motorised damper and controller, which increases both materials and programming time.
• Single-storey vs double-storey. Double-storey homes are significantly more complex. Running ducts between floors requires careful planning, additional penetrations and often more labour hours than a comparable single-storey job.
• Slab-on-ground vs raised floor. Homes built on a raised timber floor have the option of under-floor ducting, which can be a practical alternative where ceiling space is limited.
• Existing ductwork. If your home already has ducting from an older system, an installer will assess whether it can be reused or needs to be replaced. Old, leaky or undersized ductwork is rarely worth keeping.
• Electrical switchboard capacity. Older switchboards with ceramic fuses or insufficient capacity will need upgrading before a ducted system can be connected. This is a separate cost that not all homeowners anticipate.
• Distance between indoor and outdoor units. Longer refrigerant line runs require more copper pipe and insulation, and can affect system efficiency if the distance exceeds the manufacturer's recommended maximum.

None of these factors should put you off a ducted system outright. They are simply things a good installer will identify during the initial assessment and account for in the quote. The key is making sure the assessment is thorough before any work begins.

Can You Install a Ducted Air Conditioner in an Older Home?

Retrofitting a ducted air conditioner into an older Australian home is possible in most cases, but it requires a careful assessment before you commit to anything. Homes built before the 1990s were not designed with ducted air conditioning in mind, so there are a few specific things an installer needs to check before confirming the job is straightforward.

The good news is that many older homes actually have generous ceiling cavities, particularly those built in the 1960s and 1970s with high ceilings and pitched roofs. That roof space is often perfectly adequate for positioning an indoor unit and running ductwork. The main areas to assess are:

• Roof space suitability. The installer will check ceiling height, structural obstructions and whether there is a safe access point for the indoor unit and ongoing maintenance.
• Insulation levels. Older homes are often under-insulated, which affects both the heat load calculation and the efficiency of the system once installed. Topping up insulation before installation is worth considering.
• Asbestos. Homes built before 1990 may contain asbestos-containing materials in ceiling sheeting, insulation or duct lagging. This is not a reason to panic, but it does require a professional assessment before any cutting or drilling takes place. Do not skip this step.
• Electrical capacity. Pre-1990s switchboards frequently need upgrading to handle the load of a ducted system. Factor this into your budget from the start.
• Under-floor ducting. If the ceiling cavity is genuinely unsuitable, homes on raised timber floors can sometimes have ductwork run underneath instead, with vents positioned in the floor rather than the ceiling.

A qualified HVAC assessor will identify all of these issues during the initial site visit and give you a clear picture of what is and is not feasible. If ducted turns out to be impractical for your home, a high-wall split system or a multi-split setup can deliver excellent comfort without the need for roof space access at all. For a full comparison of both options, see our guide to ducted vs split system air conditioning.

Choosing the Right Ducted System Before Installation Day

Choosing the right ducted air conditioner before installation day means matching system capacity to your home's floor area, confirming the unit has inverter technology and zoning capability, and deciding whether to buy the unit separately or as part of a full supply-and-install package. Getting this decision right upfront saves you from costly undersizing, oversizing or a system that cannot do what you need it to do.

Sizing: Getting the Kilowatts Right

Capacity is the most critical variable. As a rough guide, a two-bedroom apartment or smaller home suits a system in the 8 to 9kW range, a three or four bedroom home typically needs 10 to 12kW, and a larger home with open-plan living or high ceilings will often require 12.5kW or more. These are starting points only. Your installer's heat load calculation will refine the number based on your specific home.

To give you a concrete sense of what units at each size bracket look like in practice, here are three options available at Oz Air Online in 2026:

• Fujitsu 8.5kW Ducted Air Conditioner System SET-ARTH30KHTA at $3,604. A practical entry-level option for smaller homes and apartments. Reliable, quiet and well-suited to homes where a single zone or two is all that is needed.
• Daikin 10kW Inverter Ducted Air Conditioner FDYAN100 at $4,138. A popular mid-size choice for three and four bedroom homes. Daikin's inverter compressor adjusts output continuously to match demand, which keeps running costs lower than a fixed-speed unit over a full season.
• Daikin 12.5kW Inverter Ducted Air Conditioner FDYAN125 at $4,761. The right step up for larger homes, open-plan layouts or homes in hotter climate zones where the system will work harder for longer periods.

Inverter Technology and Zoning

All three units above use inverter technology, which is worth prioritising. A non-inverter system runs at full power until the target temperature is reached, then cuts out completely. An inverter system ramps up and down continuously, which is more efficient and puts less wear on the compressor over time.

Zoning is equally worth thinking through before installation day. A zoned system lets you condition only the rooms that are occupied, which can meaningfully reduce running costs in a larger home. The number of zones you need should be confirmed with your installer before the ductwork is designed, because adding zones after the fact is expensive.

Supply-Only vs Supply-and-Install

One option many homeowners overlook is buying the unit separately online and having a local installer fit it. Purchasing supply-only through a retailer like Oz Air Online and sourcing your own licensed installer can cost less than a full supply-and-install package from a single contractor, particularly if you take the time to get two or three installation-only quotes. The trade-off is that you are coordinating two separate parties, so make sure both the unit warranty and the installation warranty are clearly documented. Browse the full range of ducted air conditioners to compare models and capacities before you commit.

How Much Does Ducted Air Conditioning Installation Cost?

Ducted air conditioning installation in Australia typically costs between $5,000 and $15,000 or more for a complete supply-and-install job, depending on home size, system capacity and how complex the installation turns out to be. That is a wide range, and the gap between a straightforward single-storey job and a complex retrofit can easily be $5,000 or more.

What Drives the Cost Up

The unit itself is only part of the total. Labour, ductwork, electrical work and any site-specific complications all add to the final figure. The factors most likely to push your quote toward the higher end are:

• Double-storey homes. Running ductwork between floors adds significant labour time and materials compared to a single-storey job of the same floor area.
• No existing ductwork. A full duct installation from scratch costs more than replacing or extending an existing system. All new ductwork means more materials, more time in the roof space and more ceiling penetrations.
• Switchboard upgrades. If your switchboard cannot handle the additional load, an electrician will need to upgrade it before the system can be connected. This is a separate cost that can add $1,000 to $3,000 depending on the work required.
• Long refrigerant line runs. The further the outdoor unit sits from the indoor unit, the more copper pipe and insulation is needed. Very long runs can also affect system efficiency and may require a larger unit to compensate.
• Difficult roof access. Low or heavily obstructed ceiling cavities take longer to work in, which adds to labour costs.

What a Quote Should Itemise

A detailed quote from a reputable installer should break out the cost of the unit, ductwork and vents, electrical work, any crane or scaffolding hire, commissioning and the compliance certificate. If you receive a single lump-sum figure with no breakdown, ask for the detail before signing. Knowing what each component costs makes it much easier to compare quotes from different installers on a like-for-like basis.

One figure that comes up regularly is the $5,000 threshold, which relates to when certain licensing and permit requirements apply. That is covered in full in the FAQ section below. For a complete breakdown of what to expect to pay across different home sizes and scenarios, see our complete Australian air conditioning installation cost guide.

Frequently Asked Questions

Can I install a ducted air conditioner myself?

No. Australian law requires ducted air conditioning installation to be carried out by a licensed HVAC technician and a licensed electrician. Handling refrigerant without an ARC licence is illegal, and unlicensed electrical work will void your home insurance and fail any future building inspection. There are no legal workarounds for this requirement.

How long does ducted air conditioning installation take?

Most residential ducted installations take one to three days from start to finish. A straightforward single-storey home with good roof access is typically done in a day. Double-storey homes, complex duct runs or difficult ceiling cavities can push the job to three days or more.

How much does it cost to install ducted air conditioning in Australia?

A complete supply-and-install ducted air conditioning job in Australia typically costs between $5,000 and $15,000 or more. The final figure depends on home size, system capacity, the amount of ductwork required and any site-specific complications such as switchboard upgrades or difficult roof access.

Can ducted air conditioning be installed in an older home?

Yes, in most cases. Many older Australian homes have generous ceiling cavities that are well suited to ducted installation. The key considerations are roof space access, electrical switchboard capacity and, for homes built before 1990, a professional asbestos assessment before any cutting or drilling takes place.

Is it cheaper to buy the unit separately and hire my own installer?

It can be. Purchasing a unit supply-only through a retailer and sourcing your own licensed installer separately often costs less than a full supply-and-install package from a single contractor. The trade-off is that you are coordinating two parties, so make sure both the unit warranty and the installation warranty are clearly documented before work begins.

Ready to Get Your Ducted System Sorted?

Ducted air conditioning installation is a job for licensed professionals, full stop. The complexity and cost vary depending on your home's size, roof space, electrical setup and whether you are retrofitting an older property or starting fresh. Most homes can accommodate a ducted system with the right assessment upfront, and getting at least two detailed, itemised quotes is the single best thing you can do before committing.

The next practical step is to get across the available systems and what they cost before your installer arrives. That way you can have an informed conversation about capacity, zoning and brand options rather than relying entirely on whoever is quoting you. Browse the full range of ducted air conditioners at Oz Air Online to compare models, capacities and prices before you call in an installer.