Ducted air conditioning installation cost in Australia (2026): prices by home size, changeover and rebates

Here’s the number everyone wants first: a new ducted reverse-cycle system in Australia costs $8,000 to $20,000 installed for most homes, and up to $25,000 for a large, fully zoned one. If you already have ducted and you’re replacing it, the honest number is usually smaller — and if you’re in Victoria, there’s a date coming that changes the maths.

The detail, with what actually moves the price:

Home	Typical capacity	Installed price (2026)
Small — 2–3 bedrooms	7–10 kW	$8,000–12,000
Medium — 3–4 bedrooms	10–14 kW	$10,000–16,000
Large — 4–5 bedrooms	14–18 kW	$14,000–20,000
Very large, fully zoned	18–24 kW	$18,000–25,000

These are typical quoted ranges from 2026 installer price guides, not a survey — there’s no official price index for air conditioning. Treat them as the sanity check for your quotes, not a promise.

Replacing an existing ducted system? Ask about a changeover first

This is the most useful thing on this page, and plenty of quotes skip it. If your home already has ducted air conditioning, you may not need to pay for ductwork again. A changeover — new outdoor unit and indoor fan coil, with your existing ducts, vents and return air reused — typically runs $8,000–14,000, saving roughly 30–40% against a full new install.

The catch is duct condition. Ducts that are leaking, crushed or older than about 15 years are usually due for replacement anyway, which puts you back at full-install money. A good installer will get into the roof and tell you which side of that line you’re on before quoting — if a quote doesn’t say whether your ducts stay or go, that’s your first question.

What actually moves the price

• Zones. Being able to shut off bedrooms by day and living areas by night is where ducted running costs are won — but each zone adds roughly $500–1,500, and smart zone controllers run $800–4,500 on top. Worth it for the rooms you’ll actually shut; not worth paying for ten zones in a house that uses three.
• Your roof space. A tight, low-pitched or cluttered roof adds labour — installers price limited access at around $500–1,500 extra, and double-storey homes generally quote higher again.
• Power supply. Systems above about 12 kW usually need three-phase power. If your home doesn’t have it, that’s $3,000–5,000+ before the air conditioner — and a good reason to check whether a right-sized smaller system does the job on single phase.
• Brand tier. Premium badges cost more for the same kilowatts. The warranty floor is the same across the majors — five years parts and labour — so make a dearer brand justify itself on something you can point to, not the logo.

Don’t buy more kilowatts than the house needs

The dearest mistake isn’t the brand — it’s the size. An oversized ducted system costs thousands more up front, then short-cycles: on, off, on, off, never running in the efficient middle of its range. Insist on a room-by-room heat-load calculation (the industry method is AIRAH’s FairAir calculator) rather than a guess off floor area. And if the system is zoned, it shouldn’t be sized as if every room runs flat-out at once — zoning exists precisely so they don’t. We’ve written the full sizing guide — including the free calculator and the questions that catch a guessed quote.

How long it lasts

A well-maintained ducted system is a 15–20 year asset — manufacturers themselves say to expect at least ten. Zone controllers and thermostats tend to give out sooner (8–12 years), and ductwork is condition-dependent: some outlives the unit, some is tired at 15. Spread the install cost over that life before comparing it with anything else — $14,000 over 18 years is under $800 a year of capital, which is the honest way to weigh it against the $600–1,200 a year it costs to run.

Rebates: one is real money, and one has a deadline

• Victoria (VEU) is the big one — but only for the right swap. Replacing a ducted gas heater with ducted reverse-cycle attracts indicative discounts of up to $2,520–5,530 depending on size (electric-resistance ducted heating, up to $5,460). Replacing an old ducted reverse-cycle with a new one earns far less — up to about $490–910. Discounts are market-based and vary by provider, so treat every figure as “up to”. The deadline: from 30 September 2026 the minimum you must pay yourself rises to $3,000 for all ducted systems — if a ducted VEU upgrade is already on your list, the sums are better before that date than after it.
• NSW has a live air-conditioner upgrade incentive under the Energy Savings Scheme — no closing date, delivered through accredited suppliers, and the government publishes no fixed dollar amounts, so get the discount in writing on the quote.
• SA (REPS) currently lists an activity specifically for ducted and multi-split reverse-cycle installs, delivered through energy retailers, with the deepest discounts reserved for concession and hardship households.
• ACT: a 50% rebate up to $2,500 exists but is concession-card-gated; ActewAGL runs a retailer offer for swapping ducted gas to ducted reverse-cycle.
• Queensland: none. The appliance rebate that briefly covered air conditioners closed in December 2023 — whatever some blogs still claim.

Rebate rules churn. Every scheme above was checked against its official page in late August 2026 — confirm on the scheme’s own site before you sign anything.

Is ducted even the right answer?

Two honest checks before you spend five figures:

If your current ducted system works, keep it. A modern zoned inverter saves roughly $200–500 a year over an old unzoned one — real money, but against an $8,000+ install it’s a 20-year payback. We’ve run that maths: the smart move is to buy the efficient, well-zoned system when you’re replacing it anyway, not before. (The one exception worth pricing: a Victorian home on ducted gas — the VEU discount plus the running-cost gap can genuinely change that answer.)

If you’re cooling two or three rooms, splits win on price. A single split system installs for roughly $1,800–2,800, so covering the rooms you actually live in can come in at around half the cost of whole-home ducted — with no roof space needed and no single point of failure. Ducted earns its premium in bigger homes where you genuinely condition most of the house, and on resale presentation. That’s a preference call; the running costs are a maths call.

And splits win on efficiency, kilowatt for kilowatt. The government’s YourHome guide puts it flatly: fixed split systems are “the most efficient domestic air-conditioners”. The engineering reason is simple — a split carries a generous heat exchanger for its capacity and delivers air straight into the room, while a ducted system spends extra energy on fans pushing air through the house, and loses heating or cooling through every metre of duct that isn’t well insulated and sealed. A typical split turns one kilowatt-hour into around 4.2 kilowatt-hours of heating; typical ducted units manage about 3.3–3.4 — roughly 20–25% less warmth per dollar, before any duct losses. And those losses are real: ducts usually run through a roof cavity that bakes all summer and chills all winter — exactly where you don’t want your cooled or heated air travelling through thin insulation. If you do go ducted: insist on well-insulated, properly sealed ducts, use the zones hard, and know that ducted systems aren’t even required to carry the Energy Rating Label that splits must display — so comparing models takes more homework.

The quote checklist

Five things a ducted quote should show before you compare it with anything:

1. Supply and install itemised — unit, ductwork, zones, electrical, as separate lines.
2. A heat-load calculation — not “we usually do 16 kW for this size house”.
3. On changeovers: a verdict on your existing ducts, in writing.
4. The warranty, split out — five years parts and labour on the unit is standard; ask what the workmanship warranty is, because that’s the one that matters in a dispute.
5. Any rebate shown as gross price, rebate line, net price — a quote that only shows the net figure is hiding the number you need to compare installers.

The verdict

• $8,000–20,000 installed for most homes; $18,000–25,000 fully zoned and large. Get three quotes — the spread between installers is real money.
• Already have ducted? Price the changeover — $8,000–14,000 with ducts reused, roughly a third cheaper, duct condition permitting.
• Size to a heat-load calc, not habit. The wrong extra kilowatts cost thousands up front and keep costing after.
• Victorian on ducted gas? Check VEU before 30 September — the minimum co-payment jumps to $3,000 after that.
• A working system stays. Efficiency alone won’t pay for a replacement — that verdict hasn’t changed.

Installed price bands: 2026 installer price guides (sparky.fyi April 2026, What’s The Damage August 2026, SolarQuotes January 2026); changeover and drivers: Essence Electrical (January 2026), TradieVerify and KYC (March 2026), sparky.fyi. Lifespan: installer consensus and manufacturer guidance. Rebates: each scheme’s official page, checked 28 August 2026. There is no public price index for air conditioning — these are typical quoted ranges, and your quotes are the real data. Prices and rebate rules move; check dates before you rely on either.