How Much Does Ducted Air Conditioning Cost in Melbourne? (2026)

A ducted system is not one product. It is an outdoor condenser, an indoor fan coil in the roof space, a trunk and branch ductwork system, an outlet and a damper for each zone, a return air path, a controller, a refrigerant pipe run and a dedicated electrical circuit. The equipment is roughly half the invoice. The rest is design and the labour to install it through a roof space you cannot stand up in.

That is why ducted quotes vary so much more than split system quotes. Two houses can take the same nominal capacity and produce a $5,000 difference, entirely because of how the air has to get from the roof to the rooms. Anyone quoting ducted cooling without inspecting the roof space is estimating rather than quoting.

It is also worth being clear about what ducted refrigerated cooling competes with. Evaporative cooling is cheaper to install and run, but it does not dehumidify and it needs windows open. Ducted refrigerated works in any conditions and heats as well. The evaporative versus refrigerated comparison sets out where each one wins.

Capacity is set by the area being conditioned, the orientation and glazing, the ceiling height, the insulation and how many zones you want running at once. Floor area is the starting point rather than the answer, but it is a useful planning guide.

As a rough guide for a reasonably insulated Melbourne home, a small house up to about 120 square metres lands on 10 to 12kW with three or four zones. A standard three bedroom house of 120 to 180 square metres is typically 12.5 to 16kW with four to six zones. A large home of 200 to 280 square metres is usually 18 to 20kW with six to eight zones. Beyond about 300 square metres, or on a double storey where the two floors behave differently, two separate systems often work better than one large one.

Zoning matters more than most people expect. A system is sized on the largest combination of zones you will run at once, not the total floor area, so a house that only ever cools the living area and the main bedroom together can often use a smaller unit than its footprint suggests. That is a genuine saving and it comes from design, not from cheaper equipment. Undersizing is the more common failure: a system that cannot reach temperature on a 40 degree day runs flat out all afternoon and wears out sooner.

Every ducted system has some form of zone control, because sending conditioned air to bedrooms nobody is using is the main way these systems waste money. What differs is how good that control is, and it is a common place for quotes to diverge without appearing to.

Basic zoning uses motorised dampers and a wall controller that turns each zone on or off. It is included in most quotes and does the fundamental job. Temperature controlled zoning adds a sensor in each zone so the damper modulates to hold that room at its own set point rather than being simply open or shut. Indicatively $150 to $400 per zone, and it is the upgrade most people notice in a house where the west facing and south facing rooms behave differently at 5pm.

Then there are the smarter controllers with a touchscreen, app control, scheduling and in some cases individual fan speed per zone. Indicatively $500 to $1,200 above a basic controller. Scheduling genuinely saves money where the occupancy pattern is predictable. App control mostly saves you walking to the hallway. One design point either way: a zoned system needs somewhere for the air to go when most zones are closed, handled with a constant zone or a bypass, and a quote that has not addressed it will produce a noisy system.

Most Melbourne homes are single phase, and most residential ducted systems up to roughly 16 to 18kW come in single phase versions a normal domestic supply can carry on a properly sized dedicated circuit. Below that threshold, phase is not something you need to think about.

Above it, three phase becomes necessary or strongly preferable. Larger systems draw more current than a single phase supply can comfortably deliver, and starting current on a big compressor is exactly the load that makes lights dip. If the property already has three phase, the larger unit is straightforward. If it does not, bringing three phase in is a distributor level job with its own cost, and it changes the arithmetic on whether one large system or two smaller ones suits a big house.

That is a real design decision, not a technicality. Two single phase systems on a large double storey home give you redundancy, better zoning between floors and no supply upgrade. One large three phase system gives you a single outdoor unit and one controller.

Either way the ducted unit needs its own dedicated circuit with appropriate protection. If the board has no spare ways, no physical room or no RCD protection, a switchboard upgrade has to happen first, and that is $800 to $3,500 or more depending on scope. The switchboard cost guide breaks down the three tiers.

This is where ducted quotes are won and lost, and it is the part that is invisible from the kerb.

The good case is a single storey house with a pitched tile or metal roof, a manhole near the middle of the house, and enough headroom to move around and get an indoor unit into position. Duct runs are short and the installer can work efficiently.

The difficult cases are predictable. A low pitch roof means crawling, which slows every stage. A cathedral or raked ceiling has nowhere to run duct at all and usually needs bulkheads. A concrete slab upper floor means the downstairs zones have to be fed from somewhere other than the roof. Second storeys added later frequently have roof spaces that do not connect to the original one, so what looks like one house is two duct systems.

Outdoor unit placement is the other half. A condenser on a level pad close to the indoor unit with a short refrigerant run is the cheap version. A narrow side boundary, a unit that has to sit on a roof mounted platform, or a run right around the house all add material and labour. Inner west homes on tight blocks hit this constraint regularly.

If you want to predict roughly where your quote will land before anyone visits, these are the drivers in order of how much they typically move the number.

Ducted air conditioning is the hardest residential job to compare on price, because the specification varies invisibly. Two quotes $4,000 apart frequently describe genuinely different systems, and the cheaper one is sometimes better value and sometimes considerably worse.

Ask every contractor for the same six items in writing. The make, model and rated capacity of the indoor and outdoor units. The number of zones and which rooms are in each. What type of zone control is included, on and off or temperature controlled. The number and position of outlets. The electrical scope, including whether a dedicated circuit and any switchboard work are priced or assumed unnecessary. And whether removal of any existing system is included.

Then look at what is not on the page. Bulkheads where there is no roof space. A larger return air path. A constant zone or bypass. Making good after the old unit comes out. Those are the items that turn up as variations on the day.

On licensing, refrigerant work must be done by an ARC licensed technician and the electrical connection by a licensed electrician who issues a Certificate of Electrical Safety. Pivot Trade Services holds REC 37223 and SAA accreditation S3962281 and installs heating and cooling across the west from Altona, with a 12 month workmanship guarantee. If a ducted system is more than the house needs, we will say so and price split systems instead.