Quick Answer
For most Melbourne homes, a ducted reverse-cycle system suits open-plan houses over 180m² where you heat multiple zones simultaneously; a split system is more cost-effective for homes under 150m² or where you mostly heat 1–3 rooms. Running costs differ significantly: a well-zoned ducted system costs roughly $1.20–$2.50 per hour; a single split system costs $0.15–$0.50 per hour. If replacing an old gas ducted heater, a modern reverse-cycle ducted system is the go-to upgrade.
Ducted Reverse-Cycle Air Conditioning
A single outdoor compressor connects to a central indoor unit in the ceiling or roof space, distributing conditioned air through insulated ducts to vents in each room. Modern systems include zone control — motorised dampers let you turn individual rooms on or off from a controller or app.
Ducted System Costs
| Home Size | System Supply & Install | Zone Control Add-On |
|---|---|---|
| Small home (under 150m²) | $8,000–$14,000 | $800–$2,000 |
| Medium home (150–250m²) | $12,000–$20,000 | $1,500–$3,000 |
| Large home (250m²+) | $18,000–$30,000 | $2,000–$4,500 |
Pros of Ducted
- Heats (and cools) every room from a single system
- Invisible — no wall unit in each room
- Zone control means you only heat occupied rooms
- Reverse-cycle: same system heats in winter and cools in summer
- Better for new builds and open-plan layouts
Cons of Ducted
- High upfront cost ($8,000–$30,000 installed)
- Duct leakage in roof space reduces efficiency (older systems especially)
- Without zone control, you heat the whole house even for one room
- Requires roof space access for installation
Split System Reverse-Cycle Air Conditioning
Each split system consists of an outdoor unit (compressor) and a wall-mounted indoor unit (head unit). You can install multiple split systems in a home — a multi-split system uses one outdoor unit to power 2–5 indoor heads, reducing outdoor units on the wall.
Split System Costs
| System Type | Supply & Install Cost | Best For |
|---|---|---|
| Single split (2.5–3.5kW) | $1,200–$2,200 | Bedroom, study, small room |
| Single split (5–7kW) | $1,800–$3,500 | Open-plan living area under 60m² |
| Single split (8–9kW) | $2,500–$4,500 | Large open-plan under 90m² |
| Multi-split (2 zones) | $4,500–$7,500 | Two main areas; one outdoor unit |
| Multi-split (4 zones) | $7,500–$13,000 | Whole home without ducting |
Running Cost Comparison
| Scenario | System | Est. Cost per Hour | Cost per Winter Month |
|---|---|---|---|
| Heat 1 bedroom (15m²) | Split system 2.5kW | $0.12–$0.25 | $18–$40 |
| Heat open-plan living (50m²) | Split system 6kW | $0.25–$0.55 | $40–$90 |
| Heat whole house (180m²) — no zones | Ducted 14kW | $1.50–$3.00 | $240–$480 |
| Heat whole house (180m²) — 2 zones active | Ducted 14kW | $0.80–$1.80 | $130–$290 |
| Heat 3 main rooms — multi-split | Multi-split 3×3.5kW | $0.50–$1.10 | $80–$180 |
Which System Is Right for Your Melbourne Home?
| Your Situation | Recommended System |
|---|---|
| New build or major renovation with roof space access | Ducted reverse-cycle with zone control |
| Replacing old gas ducted heating | Ducted reverse-cycle (reuse existing duct network if in good condition) |
| Adding heating to 1–3 rooms in an existing home | Individual split systems |
| Renter or tight budget | Split systems — most cost-effective option |
| Home under 150m², rooms used at different times | Multi-split system |
| Open-plan home over 200m² | Ducted with 3+ zones |
Tips and Gotchas
- Always use a licensed refrigeration mechanic (ARCtick) — split and ducted system installation requires an ARCtick licence for handling refrigerants. Never accept an unlicensed installer.
- Check existing duct condition before retro-fitting ducted heating. Old flex duct in attics can be collapsed or disconnected — pay for a duct inspection before assuming existing ductwork is usable.
- Inverter technology matters. Fixed-speed compressors are significantly less efficient. All new systems sold in Australia are inverter, but older systems may not be.
- Roof insulation affects ducted system efficiency enormously. An uninsulated or poorly insulated roof space means supply ducts radiate heat into the roof cavity rather than the room. Insulate before or during ducted installation.
- Split system sizing matters. Undersizing is the most common error — a 2.5kW split in a Melbourne living room will run constantly and never reach setpoint on cold days. Use a sizing calculator or ask the installer to calculate load properly.
- Victorian Energy Upgrades rebates apply to qualifying reverse-cycle installations — check eligibility at energy.vic.gov.au before purchasing.
- Gas ducted heater replacement: if your existing gas ducted heater is over 15 years old, it’s significantly less efficient than modern systems. Higher Victorian gas prices since 2024 mean replacement payback periods are shorter than ever.
Local Melbourne Resources
- Victorian Energy Upgrades — Heating Rebates
- Victorian Building Authority — Licensed Refrigeration Mechanics
- Daikin — Find an Accredited Installer (Melbourne)
- Fujitsu General — Find a Dealer
Frequently Asked Questions
Can I use my existing gas ducted heating ductwork with a new reverse-cycle system?
Sometimes, but it depends on duct condition and size. A refrigeration technician or HVAC installer can assess whether existing flex duct is in good enough condition. In many SE Melbourne homes built 1980–2005, existing ductwork is reusable, saving $3,000–$6,000 in installation costs.
Which split system brand is best in Australia?
Daikin, Fujitsu, Mitsubishi Electric, and Panasonic consistently rank highly for reliability and efficiency in Australian reviews. Daikin has an extensive local service network. Budget brands are cheaper upfront but have higher failure rates after 5–7 years.
How often does a split system need servicing?
Filter cleaning every 2–3 months (DIY, 5 minutes); professional service every 2–3 years including coil cleaning, refrigerant check and drainage test. A dirty system uses up to 25% more electricity and can grow mould on the indoor coil.
Is ducted heating being phased out in Victoria?
Gas ducted heating is not being banned outright, but new gas connections are no longer permitted in many Victorian developments from 2024, and gas prices have risen significantly. Most new builds and major renovations in SE Melbourne are now specifying reverse-cycle ducted systems over gas.
Final Thoughts
The ducted vs split system question comes down to your home size, budget, and how you actually use your home. For Melbourne winters, having a properly sized, well-zoned system matters far more than the brand. Split systems win on running cost for partial-house use; ducted wins on convenience and aesthetics for whole-home heating. The worst outcome is an undersized system that runs constantly without reaching setpoint — always err on the side of slightly larger when in doubt.
