Ducted vs Multi-Split vs Split Systems
Most people start this decision with a budget and a vague sense that ducted is the "good" option and splits are the cheap one. That's not really how it works.
All three do the same job with the same technology — a refrigeration circuit moving heat in or out of your house. What separates them is how many compressors are doing it, how the air gets to each room, and what you're willing to trade.
Key points
- Ducted reverse cycle is the recommendation for whole-of-home comfort where roof space allows.
- Individual splits suit smaller homes, one or two rooms, and pair well with evaporative cooling.
- Most residential multi-splits cannot heat and cool at the same time across different heads.
- Rebates are driven by capacity — split claims are limited to a baseline product, while multis and ducted attract the most.
Here's what each one actually is, and what nobody mentions until later.
Individual splits
One outdoor unit paired with one indoor unit, serving one room or area. Three rooms means three complete systems.
Each one is entirely independent: its own compressor, its own refrigerant circuit, its own controller.
What that gets you. Independence is worth more than it sounds. Any room can be any temperature, in any mode, at any time — one person heating the study while someone else cools a bedroom is no problem. If one system fails, the others don't care. Repairs are cheap and simple, replacement is one room at a time, and you can add another later without touching anything else.
It's also the most efficient arrangement in practice. Each inverter modulates to the load of the one room it serves, so it spends most of its life running steadily at low capacity, which is where inverters are at their best. Single splits generally carry the highest energy star ratings on the market.
What it costs you. Outdoor units. Several of them, needing wall or ground space, each with its own pipe run and wall penetration, each making some noise. On a small block, a townhouse, or anywhere with tight side setbacks, you can simply run out of places to put them. And every indoor head is a visible box on a wall.
Multi-splits
One larger outdoor unit connected to several indoor heads — typically two to five — each with its own refrigerant line running back to the shared outdoor unit.
Why people choose it. Almost always one reason: outdoor space. Apartments, townhouses, heritage properties, narrow side setbacks, or body corporate rules that permit one condenser and not four. A multi-split solves a genuine problem, and where that problem exists it's the right answer.
What you should know before choosing one.
Most residential multis can't heat and cool at the same time. All the connected heads have to be in the same mode. If someone wants heating in the study while someone else wants cooling in the lounge, one of them doesn't get it. This surprises people more than anything else on this list, and it can't be fixed afterwards.
One outdoor unit is one point of failure. When it goes, every room goes with it. With individual splits, a failure is an inconvenience in one room.
Part-load efficiency is worse. The outdoor unit is sized for the combined load of everything connected to it. Run one small bedroom head on a winter night and that large compressor has to operate at a small fraction of its capacity — often near or below the bottom of its efficient range. A dedicated single split serving that same bedroom would be running comfortably in its sweet spot. This is why multi-split systems generally carry lower star ratings than the equivalent single splits, and it shows up on the bill.
Not every head delivers full capacity at once. Multis are sized on the assumption you won't run everything at maximum simultaneously. On the most extreme days, that assumption is exactly when it stops holding.
The upfront cost is closer than you'd think — but rebates change the maths. Past two or three heads, the hardware and labour on a multi often lands near or above the same number of individual splits: longer and more complex pipework, more joints, a bigger outdoor unit. Rebates usually close that gap and then some — see the rebate section below, because it affects all three options and it's the single biggest variable in what you actually pay.
Repairs are more expensive and more disruptive. Shared refrigerant circuits are harder to diagnose, and a fault can take the whole house out until it's resolved.
Repairs are more expensive and more disruptive. Shared refrigerant circuits are harder to diagnose, and a fault can take the whole house out until it's resolved.
Ducted reverse cycle
One outdoor unit and one indoor fan coil, usually in the roof space, distributing conditioned air through ductwork to outlets in each room.
What that gets you. The house looks like it has no air conditioning. Just vents. Even, consistent temperatures across the whole home rather than pockets of conditioned air, and the indoor unit is up in the roof rather than on a wall, so living spaces are quiet. It's usually the strongest option for resale value, and with proper zoning and per-zone sensors you get room-level control that a bank of splits can't quite match for a whole house.
What it costs you. The highest upfront price and a genuine design exercise — heat load calculation, duct sizing, return air, zone layout. It needs adequate roof space, which rules out some homes and makes double-storey more complicated. It's one system for the whole house, so a failure affects everything. And it's the option most exposed to installation quality: undersized return air, kinked duct or under-rated duct insulation will cripple an otherwise excellent system, and none of it is visible once the manhole is shut.
Quick comparison
| Individual splits | Multi-split | Ducted | |
|---|---|---|---|
| Outdoor units | One per room | One total | One total |
| Different modes at once | Yes | Usually no | No (zones share mode) |
| If it fails | One room affected | Whole house | Whole house |
| Part-load efficiency | Best | Weakest | Good with zoning |
| Visual impact indoors | Head in every room | Head in every room | Vents only |
| Upfront cost | Low to moderate | Moderate to high | Highest |
| VEU rebate | Limited by baseline capacity | Among the highest | Among the highest |
| Design required | Minimal | Moderate | Substantial |
| Retrofit difficulty | Easiest | Moderate | Hardest |
What the rebates do to this comparison
This is the part that most changes the real cost, and it doesn't work the way people assume.
Under the Victorian Energy Upgrades program, the rebate is driven by capacity, not by how many boxes get installed. Putting in four small splits doesn't generate four rebates.
Individual splits are limited. The claim is made against a baseline product, typically around 7–8kW. That caps what a split installation can attract regardless of how many rooms you're doing.
Multi-splits and ducted systems attract the most. Both are larger-capacity systems, and the rebate scales accordingly. This is why the after-rebate price on a multi or a ducted system often lands much closer to a set of individual splits than the list prices suggest — and sometimes below.
Replacing ducted gas heating attracts more again. If you're taking out a ducted gas heater and putting in reverse cycle, the rebate is higher than a straight cooling upgrade. You're displacing gas, and the program rewards that. If you have ducted gas heating and you're weighing up your options, this is the single most valuable position to be in — and it's worth getting a figure before your gas heater fails and makes the decision for you.
The practical instruction: ask for the rebated price on each option. Comparing list prices will point you at the wrong answer, and the gap is large enough to change which system you choose.
How we'd steer you
Whole home? Ducted reverse cycle. It's what we recommend for whole-of-home solutions and it's what the technology is designed for — even temperatures throughout, room-level control through zoning, nothing visible but vents, and the strongest position at resale. If you have the roof space and you're conditioning the whole house, this is the answer.
Smaller home, or one or two rooms? Individual splits. Straightforward, efficient, cheap to run and cheap to fix, and there's no case for anything more complex.
Already have evaporative cooling? A single split in the living room is one of the smartest additions you can make. It covers the humid days when evaporative cooling struggles, gives you one sealed room you can properly control, and adds reverse cycle heating — for a fraction of the cost of replacing the whole system.
Several rooms but nowhere to put outdoor units? Multi-split. Apartments, townhouses, tight setbacks, body corporate restrictions. It exists to solve that problem, and the rebate position on multis is strong enough that it's often the better commercial answer even where space isn't the deciding factor. Just go in knowing the trade-offs above — particularly the same-mode limitation.
Double storey? Often a hybrid. Ducted from the roof serves upstairs well, while downstairs is awkward without bulkheads — so a common answer is ducted upstairs with splits or a second system below. Don't assume it has to be one approach for the whole house.
Whichever you choose, this matters more
Sizing. A system of any type that's been sized off floor area rather than a heat load calculation will disappoint you — undersized systems never recover on a 40°C day, and oversized ones short-cycle, cost more and control humidity poorly.
Ask whether a heat load calculation was done for your home specifically. The answer tells you a lot about the quote.