What Affects the Cost
House size and zones. A 3-bedroom home with a single zone needs a 10–12 kW system. A 5-bedroom home across two storeys with 4-zone control needs 16–20 kW and substantially more ductwork, diffusers, and a larger unit.
Roof cavity clearance. The indoor unit needs at least 500mm of clearance. Many older Sydney homes have adequate cavity under terracotta tiles, but low-pitch roofs in some newer builds can be problematic and may require slim-line indoor units.
New install vs replacement. Replacing an existing ducted system reuses duct routes and penetrations, typically saving 30–40%. But ductwork over 15 years old may need replacing due to degraded insulation (flex duct in hot Sydney roof spaces degrades faster).
Three-phase power. Systems above 12kW need three-phase. Many larger Sydney homes already have it, but if yours does not, the upgrade through
Ausgrid adds $3,000–$5,000 or more.
Zoning and smart control. A basic 2–4 zone controller adds $800–$1,500. Smart systems like AirTouch 5 or iZone with individual room temperature sensors run $2,500–$4,500 installed. The running cost savings from zoning are significant for 4+ bedroom homes.
Brand and efficiency. A Daikin or Mitsubishi Electric system costs $1,000–$2,000 more than a Samsung or LG equivalent, but delivers better humidity handling (important for Sydney's summers), quieter operation, and wider service networks.
Strata restrictions. Townhouse and apartment installations may require body corporate approval, restricted installation hours, and specific outdoor unit placement, all of which add time and potentially cost.
A replacement system in a single-storey, 3-bedroom brick veneer home with good roof access, existing ductwork, and single-zone control sits toward $8,200. A new installation in a 5-bedroom, two-storey home in Strathfield or Epping with 4-zone smart control, three-phase upgrade, premium brand, and complex duct runs pushes toward $22,400.
Sydney-Specific Considerations
Sydney's established suburbs tell two different ducted aircon stories. Inner-west terraces and semi-detached homes in Marrickville, Leichhardt, and Newtown often have low-pitch or skillion roofs with minimal cavity, making ducted installation difficult or impossible without significant structural modifications. These areas tend to favour split systems instead. Where ducted is feasible in terraces, expect longer duct runs through tight roof spaces, increasing both material and labour costs.
The middle-ring suburbs are where ducted systems thrive. Strathfield, Epping, Ryde, and Burwood have generous terracotta tile roofs with ample cavity space. Post-war brick veneer construction makes cable and pipework routing straightforward. Many of these homes already have ducted systems from the 1990s or early 2000s that are now due for replacement. For these properties, the replacement cost is lower because existing duct routes and electrical circuits can often be reused, even if the ductwork itself needs upgrading to current R-value standards.
Western Sydney's newer estates in Kellyville, Marsden Park, and Oran Park are often designed with ducted aircon as a standard inclusion. Open-plan layouts, engineered roof trusses with ample clearance, and pre-wired electrical make installation faster and cheaper. Builders typically offer ducted as a package upgrade during construction. These suburbs also experience some of Sydney's most extreme summer temperatures, regularly exceeding 40°C, so a system sized for the heat load (often 14–18 kW for a 4-bedroom home) is a necessity rather than a luxury.
For apartments, ducted air conditioning is rarely feasible. The lack of roof cavity or ceiling void eliminates the ductwork option in most Sydney apartment buildings. Some newer developments in Green Square and Zetland include bulkhead spaces that can accommodate slim-line ducted units, but this requires confirmation from the building manager and often strata approval before proceeding.
Outdoor unit noise is worth considering in Sydney's higher-density suburbs. Under the Protection of the Environment (Noise Control) Regulation, councils can act on complaints about air conditioning noise. Premium inverter units from Daikin and Mitsubishi Electric operate as low as 40 dB(A), while budget systems may exceed 55 dB(A). Positioning the outdoor unit away from neighbours' bedroom windows, even if it means a slightly longer refrigerant pipe run, is usually worth the extra cost.
Hiring a Licensed Air Conditioning Technician in NSW
Ducted air conditioning installation requires two licences. The installer must hold an ARC (Australian Refrigeration Council) authorisation to handle refrigerant gases (R32 in all modern systems). The electrical work must be performed by an electrician licensed through NSW Fair Trading. Many aircon companies employ both, but verify both credentials before work begins.
The electrician must issue a CCEW (Certificate of Compliance Electrical Work) for any new circuits or switchboard modifications. Ask for the ARC authorisation number and the CCEW before making final payment. You can verify licences on the NSW Fair Trading and ARCtick websites.
Worth checking:
ARC authorisation number (verify on the ARCtick website)
NSW electrical licence (verify on the Fair Trading website)
That the quote specifies the brand, model, capacity (kW), number of zones, and what is covered by warranty
That the quote is based on an on-site inspection, not a phone estimate
CCEW confirmation before making final payment
A good installer will conduct a site inspection, measuring roof cavity clearance, assessing insulation, checking electrical capacity (single-phase vs three-phase), and discussing zoning options before providing a fixed-price quote. They should also specify the design temperature they are sizing for and explain why they have chosen a particular system capacity for your home.
How We Calculate
Estimates are based on surveyed trade rates for licensed air conditioning technicians in the Sydney metro area, adjusted for property type and system complexity. All prices include GST. Figures cover standard residential ducted air conditioning systems. Commercial installations are not included.