For most Australian homes, switching from gas ducted heating to ducted reverse-cycle is worth it once the gas system is ageing or you also want cooling. Reverse-cycle systems turn one unit of electricity into three to six units of heat, so they usually cost less to run than gas. They also cool the house in summer. The main hurdle is the upfront cost, which depends heavily on whether your existing ductwork and electrical supply can be reused.
At Solus Air, our ARCtick-licensed technicians carry out gas to reverse-cycle conversions across NSW, the ACT, Queensland, Victoria, South Australia and Western Australia. Most conversions we complete take one to two days. The homeowners who get the best result weigh four things together. These are the age of their gas unit, their need for cooling, the condition of their ducts, and the rebates available in their state.
This guide compares the two systems on running costs, comfort, installation and policy, then covers when switching makes sense and when it doesn’t.
What is the difference between gas ducted heating and reverse-cycle?
Gas ducted heating burns gas in a furnace and pushes the warm air through ducts to vents in each room. It only heats. Reverse-cycle air conditioning is a heat pump that moves heat from the outside air into your home in winter, and reverses the process to cool the house in summer.
That difference in how heat is made is what drives most of the cost gap. A gas furnace can never deliver more heat than the energy in the gas it burns. A heat pump moves heat that already exists in the outside air, so it can deliver several times more heat than the electricity it uses.
Is reverse-cycle cheaper to run than gas ducted heating?
Yes, in most Australian homes reverse-cycle costs less to run than gas ducted heating. Sustainability Victoria says electric reverse-cycle systems are more efficient and cheaper to run than gas ducted and gas room heaters.
The efficiency figures explain why:
- Reverse-cycle: The Australian Government’s energy.gov.au says reverse-cycle air conditioning is 300 to 600% efficient. One unit of electricity becomes three to six units of heating or cooling.
- Gas heaters: The same source says gas heaters typically convert only about 85% of gas into usable heat. The rest is lost through the flue.
- Gas ducted specifically: energy.gov.au describes ducted gas heating as expensive to operate because of its significant gas consumption, plus the electricity needed to run the fans.
How much does a unit of heat cost from gas vs reverse-cycle?
Electricity costs more than gas per unit of energy, but a heat pump uses far less of it. The table below shows the cost of delivering one kilowatt-hour of heat into your home under typical price assumptions.
| Heating source | Energy price assumed | Efficiency assumed | Cost per kWh of heat delivered |
| Gas ducted | 4 cents per MJ | 85% | About 16.9 cents |
| Gas ducted | 6 cents per MJ | 85% | About 25.4 cents |
| Reverse-cycle ducted | 30 cents per kWh | 300% (COP 3) | About 10 cents |
| Reverse-cycle ducted | 30 cents per kWh | 400% (COP 4) | About 7.5 cents |
Illustrative calculation. One kWh equals 3.6 MJ. Gas efficiency from energy.gov.au, heat pump efficiency within the 300 to 600% range published by energy.gov.au. Your tariffs, climate and system will change the numbers, so check your own bills.
On these assumptions, reverse-cycle heat costs roughly half to a third of gas heat. The gap widens further if you run the system on rooftop solar during the day.
Are ducted reverse-cycle systems as efficient as split systems?
No, ducted reverse-cycle systems are a little less efficient than wall-mounted split systems. energy.gov.au notes ducted units use a larger fan and lose some energy through the ductwork. They are still far more efficient than gas, and they heat the whole house from one system, which is why most people replacing gas ducted choose ducted reverse-cycle.
How much could switching save you on energy bills?
Savings depend on your climate, house size and how much you heat. The clearest published figure comes from the Victorian Government. Its Victorian Energy Upgrades program estimates bill savings of up to $1,140 a year when a ducted gas heater is replaced with an efficient reverse-cycle air conditioner.
A few factors push savings higher:
- Removing gas entirely. If heating is your last gas appliance, disconnecting also removes the daily gas supply charge. If you keep a gas cooktop or hot water, you keep paying that charge.
- Rooftop solar. Sustainability Victoria notes the benefits of reverse-cycle heating are even greater with solar panels, because the system uses more of your own solar output.
- Cold climates with long heating seasons. The more you heat, the more each cheaper unit of heat adds up.
- Replacing a separate cooling system. If you run gas ducted in winter and a separate evaporative cooler or split systems in summer, one reverse-cycle system replaces both.
How do gas ducted and reverse-cycle heating compare side by side?
| Factor | Gas ducted heating | Ducted reverse-cycle |
| Heating efficiency | About 85% on typical models | 300 to 600% |
| Cooling | None, needs a separate system | Heats and cools |
| Running cost | Higher per unit of heat | Lower per unit of heat |
| Solar compatibility | Cannot run on solar | Can run on rooftop solar |
| Combustion in the home | Burns gas, needs a flue | No combustion |
| Warm-up feel | Very hot air, fast warm-up | Gentler warm air, steadier temperature |
| Ductwork needs | Existing ducts in place | Ducts insulated to at least R1.5 |
| Electrical needs | Power for the fan only | Higher load, may need a dedicated circuit |
| New homes in Victoria and the ACT | No new gas connections | Standard choice |
Sources: energy.gov.au, YourHome, Sustainability Victoria, Victorian Government and ACT Government, linked throughout this article.
Does reverse-cycle heating feel as warm as gas?
Reverse-cycle heating keeps a house just as warm, but it feels different. Gas ducted systems push out very hot air, so a cold room warms up quickly. Reverse-cycle systems deliver warm air and hold a steady temperature. Many people find this more comfortable once they are used to it.
The difference is most noticeable when you switch the system on in a cold house. With a reverse-cycle, set a timer so the house is already warm when you get up or get home.
Does reverse-cycle work in very cold weather?
Yes, but heat pump output drops as the outside temperature falls, and units run periodic defrost cycles in frosty conditions. In most Australian climates this is not a practical problem if the system is sized correctly.
If you live somewhere with regular frosts, such as Canberra or parts of regional Victoria, check the cold zone rating on the Zoned Energy Rating Label. Energy Rating explains that the cold zone is based on Canberra, and that the label shows a second heating capacity figure at 2°C because output varies with outside temperature. Compare that 2°C figure, not just the headline capacity, when choosing a system for a cold climate.
Can you reuse gas ducted heating ducts for reverse-cycle?
Sometimes. Existing ductwork can often be reused if it is in good condition, adequately insulated and sized for the new system. This is where the biggest cost difference between conversions comes from.
The Australian Government’s YourHome guide says ducts must be insulated to at least R1.5, with joints sealed to prevent condensation and leakage. That matters more for reverse-cycle than for gas, because cold air in summer creates condensation risk that a heating-only system never had.
Here is what we check on every conversion:
- Insulation rating. Older gas ducts were often installed with lighter insulation than current standards require. Under-insulated runs need replacing.
- Condition. Crushed, torn or disconnected ducts leak air into the roof space and waste energy.
- Sizing and layout. Reverse-cycle systems move air differently, so some runs or vent positions may need changing to balance airflow.
- Floor vs ceiling vents. Many gas systems use floor vents. These work well for heating but poorly for cooling, since cool air sinks. Moving vents to the ceiling adds cost but improves summer comfort.
- Cleanliness. Ducts that have run for 15 or 20 years collect dust. A full ducted system clean before reconnecting is worth considering.
At Solus Air, our approach is to reuse existing ductwork wherever it is up to standard, because the ducts are usually the expensive part. Runs that fall short need repairing or replacing before the new system goes in.
What else is involved in switching from gas to reverse-cycle?
A typical conversion involves more than swapping one unit for another. Expect these steps:
- Assessment. A technician checks the ducts, roof space, switchboard and a spot for the outdoor unit.
- Sizing. The new system should be sized to your rooms, insulation and windows. Copying the old furnace’s rating often leads to the wrong capacity.
- Removing the gas furnace. A licensed gas fitter disconnects and caps the gas supply and removes the flue.
- Electrical work. A larger ducted system usually needs a dedicated circuit. Some older homes also need a switchboard upgrade.
- Installing the outdoor and indoor units. The indoor fan coil usually goes in the roof space, and the outdoor unit needs clearance and a stable base.
- Ductwork and vents. Existing ducts are reconnected, repaired or replaced, and a zoning controller can be added.
- Commissioning. The system is tested, and you should receive the relevant electrical and gas compliance certificates.
How much does it cost to switch from gas ducted to reverse-cycle?
A whole-home ducted reverse-cycle system typically costs $10,000 or more installed for a standard house. CHOICE says you will be hard-pressed to buy a ducted reverse-cycle system for less than $5,000. For a typical freestanding house, the cost can easily reach $10,000 or more, and large or multi-storey homes are probably looking at $15,000 or more.
The biggest swing factors on a conversion are:
- Whether the ductwork can be reused or needs replacing.
- Whether the switchboard or electrical supply needs upgrading.
- The system capacity and number of zones.
- Roof space access and the distance between indoor and outdoor units.
- Your location, since regional installs can cost more.
Are there rebates for replacing gas ducted heating?
Yes, in some states. In Victoria, the Victorian Energy Upgrades program offers discounts of up to $5,530 when a ducted gas heater is removed or replaced with an efficient reverse-cycle air conditioner. Other states and territories run their own programs, and eligibility and amounts change, so check your state government’s energy website before you get quotes.
Is gas heating being phased out in Australia?
Gas is being phased out for new homes in some states, but existing homes can keep their gas heating. Victoria has required new homes needing a planning permit to be all-electric from 1 January 2024. The ACT has prevented new gas network connections in residential zones since 8 December 2023.
The ACT Government states that homes with a gas meter already installed can keep using their connection. Nobody is being forced to remove a working gas heater. Policy direction is still worth weighing if your system is nearing replacement, because it affects the long-term cost of staying on gas.
When is it worth switching to reverse-cycle?
In our experience, switching makes the most sense when two or more of these apply:
- Your gas ducted unit is over 15 years old or needs a major repair such as a heat exchanger.
- You want cooling as well as heating, or you run a separate cooling system you would like to retire.
- Your existing ducts are in reasonable condition and can be reused.
- You have rooftop solar, or plan to install it.
- Heating is your last gas appliance, so switching removes the gas supply charge.
- You live in a state with a rebate for replacing gas ducted heating.
When should you keep your gas ducted heating?
Keeping gas can be the better call in some situations:
- Your gas unit is fairly new. A well-maintained system under about 10 years old still has plenty of life in it. Keep it serviced and plan the switch for later.
- You don’t need cooling and your heating bills are modest. The running cost savings may take many years to cover the upfront cost.
- Your ducts and switchboard both need replacing. A full duct replacement plus electrical upgrade can make the payback period long, especially without a rebate.
If you are keeping gas for now, have it serviced regularly so it runs safely and efficiently. Sustainability Victoria recommends that anyone buying a new gas ducted heater choose a high-efficiency model of 5 stars or higher.
Frequently asked questions
Is ducted reverse-cycle cheaper than gas ducted heating in Melbourne?
Yes, in most Melbourne homes. Sustainability Victoria says electric reverse-cycle systems are cheaper to run than gas ducted heating, and the Victorian Energy Upgrades program estimates savings of up to $1,140 a year when replacing a ducted gas heater.
How long does a gas to reverse-cycle conversion take?
Most conversions take one to two days. Jobs that need new ductwork throughout or a switchboard upgrade can take longer.
Can I keep my gas hot water and switch my heating to reverse-cycle?
Yes. Heating and hot water are separate systems. The trade-off is that you keep paying the daily gas supply charge while any gas appliance stays connected.
Do I need new ducts to switch from gas to reverse-cycle?
Not always. Ducts can be reused if they are in good condition, insulated to at least R1.5 and suited to the new system’s airflow. Damaged or under-insulated runs need replacing.
Will reverse-cycle heating increase my electricity bill?
Yes, your electricity bill will go up. In most homes, your gas bill will fall by more. Because a heat pump delivers three to six units of heat per unit of electricity, total heating costs are usually lower.
Is a bigger reverse-cycle system better for heating?
No. An oversized system cycles on and off and wastes energy, while an undersized one runs flat out on cold nights. The right capacity comes from measuring your rooms, insulation and windows.
Should you make the switch?
If your gas ducted heater is ageing, you want cooling, or you have solar, switching to reverse-cycle is usually worth it. You will pay less per unit of heat, get cooling from the same system, and move away from a fuel that new homes in Victoria and the ACT can no longer connect to. If your gas system is newer and you don’t need cooling, keep it serviced and revisit the decision when it nears the end of its life.
If you would like to know what a conversion would involve for your home, book a conversion assessment. One of our technicians will check your ducts, switchboard and heating needs, and confirm the price before any work begins.
