How does reverse cycle heating work?
A reverse cycle system doesn't make heat the way a bar heater does. The ACT Government's guide explains that it pulls heat out of the outside air and moves it indoors, using a compressor, an expansion valve and two heat exchangers. In summer the same system runs the other way.
There's more heat in cold air than you'd expect. The same guide says air at 0 degrees still holds over 90% of the heat energy of air at 40 degrees, and that good systems keep working at minus 10 degrees in winter.
That's why the efficiency figures look odd. The guide puts reverse cycle systems at 250 to 600% efficiency, known as the coefficient of performance (CoP), and says a system with a CoP of 6 uses half the energy of one with a CoP of 3 for the same heat.
How it compares with gas and electric heaters
The ACT Government's heater comparison lists a gas wall heater at 85% efficiency and an electric element heater at 100%, against 370% to 600% for reverse cycle. It also says gas heats a home quickly, but reverse cycle has much lower running costs.
For your own home, take the unit's input power in kW, multiply it by the hours you run it, then by your own electricity rate. The running cost tool does the sums.
Switching from gas is a choice, not a rule, for Victorian owners of existing homes: DEECA says there's no requirement to upgrade gas space heating. If you do swap gas ducted for ducted reverse cycle, the ACT Government says the old gas ducts are too narrow to reuse. See switching from gas to electric.
Split, multi-split or ducted reverse cycle?
| Split | Multi-split | Ducted | |
|---|---|---|---|
| What it covers | One room or an open living area | Two to five rooms, each with its own indoor unit | The whole house, through ceiling or floor vents |
| Outdoor units | One for each indoor unit | One for several indoor units | One |
| Zoning | Switch on only the units you need | Very good: you can turn off unused rooms (ACT Government) | Limited to good, depending on the system (ACT Government) |
| Efficiency (CoP), average to excellent | 3.7 to 6.4 | 3.7 to 5.1 | 3.5 to 5.0 |
| Worth knowing | A whole house needs several | All indoor units share heating or cooling mode (Mitsubishi Electric) | Some heat is lost through the ducts, so insulate them to at least R1.5 |
Choosing one for heating, not just cooling
Each type has its own page: split system installation, multi-split systems and ducted air conditioning. Whichever you pick, if you live somewhere cold, judge it on its heating.
The Zoned Energy Rating Label shows cooling stars in blue and heating stars in red, and the example label in the ACT Government's guide groups Canberra, Hobart and Melbourne in the cold zone. It also shows heating capacity at 7 degrees and at 2 degrees outside. On a frosty morning, the 2 degree figure tells you more than the headline kW.
The ACT Government also suggests asking whether a split has an 'H2' rating, which it says means the unit will work efficiently through a Canberra winter.
Expect the odd pause on cold, damp mornings. Mitsubishi Electric says heating can stop for about 10 minutes while the outdoor unit defrosts, and the white vapour you may see outside is part of that. It isn't a fault.
Discounts and rules worth knowing
Victorian Energy Upgrades (VEU) air conditioner categories only cover systems that can both heat and cool. Discounts come from accredited private providers and the program is voluntary. From 30 September 2026, a ducted VEU job carries a minimum co-payment of $3,000. Our VEU guide explains how it works.
In NSW, the Energy Savings Scheme covers installing or replacing an air conditioner with a high efficiency one, through installers who partner with Accredited Certificate Providers. The nomination form has to be signed before installation starts.
For Victorian landlords: from 1 March 2027, when the main living area heater permanently fails and can't be repaired, the replacement generally has to be energy efficient and electric, such as a non-ducted reverse cycle unit rated 2 stars or more for heating. A working gas heater can stay. See the rental rules guide.
What's on you, and what's on the installer
You can
- List the rooms you heat in winter and the ones you cool in summer. They're often not the same.
- Read the red heating stars for your climate zone on the energy label.
- Set it sensibly. The federal Energy Rating calculator suggests 18 to 20 degrees in winter and 25 to 27 in summer.
- Clean the filters as your manual says. Daikin's general rule is every two weeks.
Leave to a licensed installer
- The heat load, worked out for both heating and cooling.
- Choosing a model with enough heating capacity on cold mornings.
- All refrigerant and electrical work.
- Disconnecting the old gas heater (a gasfitter's job).
Questions to ask before you buy
- What's the heating capacity at 2 degrees outside, not just the rated kW?
- How does this model rate for heating in my climate zone?
- Are you, or the provider you work with, accredited for VEU or the NSW Energy Savings Scheme?
What we'd do
If it were our home
In a heating city, we'd choose the system on its heating figures first and let cooling come second. We'd ask for the heating capacity at 2 degrees, check the red stars for the cold zone, and have a reverse cycle specialist size it for the coldest room you actually use. In Brisbane or Darwin, which the label puts in the hot zone, we'd flip that order.
