What Affects the Cost
Number of units needed. Perth's heat means most homes want aircon in every liveable room, not just the lounge. Three to five indoor units is common for a four-bedroom home. A 2-head multi-split runs $4,200–$5,000 supplied and installed; each additional head adds $1,000–$1,600. When individual single splits make more sense than a multi-split depends on room layout and pipe run distances.
Pipe run length. Back-to-back installs are cheapest. Copper refrigerant pipe costs $50–$130/m beyond the standard included length. Double-storey homes in newer Perth estates like Baldivis, Ellenbrook, and Byford often need 8–12m pipe runs from upstairs bedrooms down through wall cavities, pushing labour to $1,200–$2,200+.
Sandy soil. Perth's sandy ground can shift under a poorly prepared outdoor unit pad. A concrete slab ($60) needs a compacted base, or use wall brackets (~$90) fixed to the house structure to avoid ground settlement altogether.
Switchboard capacity. Multiple aircon circuits on a single switchboard can push it past capacity, particularly if the home also runs solar and a pool pump. A
board upgrade adds $1,500–$2,800. Each split system needs a dedicated 25A RCBO.
Hard water and condenser coils. In suburbs with bore water or high-calcium mains supply (common in Joondalup, Wanneroo, and northern corridor), mineral deposits build up on condenser coils, reducing efficiency. Corrosion-resistant coatings or regular hosing helps. Panasonic's anti-corrosion condenser design is popular in these areas.
Core drilling. Older homes in Fremantle, Mount Lawley, and Subiaco with double-brick or limestone block walls need core drilling ($150–$250) for the pipe penetration.
Access and storey. Second-storey installs on Perth's common double-storey designs may need scaffolding ($150–$300/day) for the outdoor unit or long pipe runs through wall cavities.
A single back-to-back install of a 2.5kW unit in a newer single-storey home in Baldivis or Butler, with the switchboard nearby and spare capacity, sits toward $1,500. A multi-split system with four or five heads across a double-storey home in Applecross or Dalkeith, long pipe runs, a switchboard upgrade, and condenser coating for hard water areas pushes toward $9,800.
Perth-Specific Considerations
Perth's summer heat is in a different league from the eastern capitals. When the mercury hits 40+ degrees for multiple consecutive days, which happens regularly from December through February, the outdoor compressor is working at its thermal limits. This makes outdoor unit placement more important than in cooler cities. A shaded location on the south or east side of the house, away from direct afternoon sun, helps the unit run more efficiently and last longer. If the only viable position is on a west-facing wall, a purpose-built shade structure over the outdoor unit is a worthwhile addition.
The newer suburbs that make up a large share of Perth's housing stock, including Baldivis, Ellenbrook, Byford, Piara Waters, and Harrisdale, are predominantly double-storey with lightweight construction. Installations here are generally straightforward in terms of wall penetration, but the pipe runs from upstairs bedrooms down to ground-level outdoor units can be 8–12 metres through wall cavities. Many of these homes are built without aircon, with builders offering it as an optional extra, so first-year installations are very common.
For older homes in suburbs like Fremantle, Mount Lawley, Subiaco, and Cottesloe, the construction varies from double brick to limestone block, both of which require core drilling. Western Power manages the distribution network, and three-phase supply is available in some established suburbs, which can be useful for larger multi-split systems.
Hiring a Licensed Air Conditioning Technician in WA
Split system installation in WA requires an ARC (Australian Refrigeration Council) licence for refrigerant handling. The electrical work must be performed by a licensed electrician registered with Building and Energy (DMIRS). Many Perth aircon installers hold both licences, but confirm before booking.
Your installer must lodge a Notice of Completion (NOC) with Building and Energy for the electrical circuit. You should also receive an ARC job card confirming refrigerant type (R32), quantity charged, and leak test results. Perth's smaller trade pool means lead times can blow out during peak summer season, so booking your install for autumn or spring often means better availability and sometimes better pricing.
How We Calculate
Estimates are based on surveyed trade rates for licensed air conditioning technicians in the Perth metro area, adjusted for property age. All prices include GST. Figures assume a standard residential split system installation.