Gas Ducted vs Reverse Cycle Heating (2026 Comparison)

A gas heater burns fuel and converts 80 to 92 percent of it into heat. That figure is a ceiling, not a starting point. No burner, however well engineered, can extract more energy from the fuel than the fuel contains, so the best a gas appliance can ever do is approach one unit of heat per unit of fuel and fall slightly short.

A reverse cycle system does something categorically different. It does not make heat, it collects heat that already exists in the outside air and moves it indoors using a refrigerant circuit. That is why it returns 3 to 4 units of heat for every unit of electricity it consumes. The comparison is between a ceiling of about 0.92 and a return of 3 to 4, which is the entire reason the running costs diverge as much as they do.

This surprises people because it feels like it breaks a rule. It does not. The energy is not being created, it is being relocated, and the electricity is paying for the relocation rather than for the heat itself. The same principle is why a heat pump hot water system uses about a third of the electricity of a conventional element tank.

In cents, reverse cycle heats a room for roughly 28 to 36 cents an hour, against 50 to 72 cents an hour for ducted gas. Across a Melbourne winter that lands at $200 to $450 a year for most households.

Two things push that higher. The first is the daily gas supply charge. If hot water, cooking and heating are the only reasons you hold a gas connection, moving all three to electricity lets you disconnect and stop paying a fixed charge every day whether you use gas or not. Heating is usually the last and largest of the three, which is why it is the appliance that unlocks the saving.

The second is solar. A reverse cycle system running during daylight uses your own generation, which is worth far more to you than exporting it at current feed-in rates. Gas cannot use your solar under any circumstances. For a household with panels already on the roof, that shifts the comparison further than the headline cents per hour suggests.

One thing that does not change: comfort. Both systems will heat a Melbourne house properly when correctly sized. Anyone telling you reverse cycle cannot heat in a Melbourne winter is describing equipment from twenty years ago. Our guide on cutting winter heating bills covers the rest of the picture, including the draught sealing that matters regardless of which system you run.

Where a figure is missing below it is because it varies too much by house for a single number to be honest, and we would rather leave a gap than invent one.

This is the first question anyone with existing gas ducted heating asks, and the honest answer is sometimes, and it needs looking at rather than assuming.

The reason it is not automatic is that the two systems move air differently. A gas furnace delivers a smaller volume of much hotter air. A ducted reverse cycle system delivers a larger volume of air at a milder temperature. Ductwork sized for the first job is frequently undersized for the second, and pushing more air through undersized ducts produces noise, poor airflow at the far outlets and a system that never quite performs the way the specification promised.

Return air is the other common blocker. Gas ducted systems often run with a modest return air path, whereas reverse cycle needs a generous one, because it is recirculating a much larger volume. On a lot of houses the return air grille has to be enlarged or a second one added, and that is real work rather than a swap.

What frequently can be kept is the duct runs themselves in newer houses where they were sized generously, the ceiling penetrations, and sometimes the outlet positions. What rarely survives is old flexible duct that has been in a roof space for two decades, has crushed sections where someone knelt on it, or has failed insulation. That is worth replacing regardless of which system you fit, because it is losing heat into your roof space right now.

The practical approach is an inspection in the roof space before quoting, measuring the duct sizes and looking at the return air. That inspection is what separates a quote that holds on the day from one that grows. Where the ducts genuinely cannot be reused we say so at quote rather than discovering it halfway through the job.

There are two very different changeovers and they should not be quoted as if they were the same thing.

The first is replacing whole house ducted gas with ducted reverse cycle. That is the larger job, and it is quoted per house because duct condition, return air, zoning and the outdoor unit position all vary. This is the option that keeps the whole house on one system and one controller.

The second is walking away from ducted heating altogether and fitting split systems to the rooms you actually use. A split system runs $2,500 to $7,500 installed depending on capacity and the number of indoor heads. A single head in a living area sits near the bottom, a multi head system covering a living area and two bedrooms nearer the top. For a lot of households this is the better value path, because it stops paying to heat a hallway and three empty bedrooms, and because the same units cool in summer. Households across Altona and the inner west frequently land here.

On the discount side, Victorian Energy Upgrades comes off the installation invoice directly rather than being claimed afterwards, and there is no income test. The property must be at least two years old and there is a minimum customer contribution of $200 including GST. Because it is an invoice discount there is no waiting period and nothing to submit once the job is finished. The honest caveat is that the program changed on 30 September 2026, so we put the current amount in writing at quote and update it if it moves before the work goes ahead.

The other line worth checking early is the switchboard. Reverse cycle equipment needs dedicated circuits with appropriate protection, and on older homes that can mean a switchboard upgrade before anything else happens.

We fit both, and there are households where the correct advice is to keep the gas running for now. Pretending otherwise would be a sales pitch rather than an answer.

The clearest case is a working furnace that is not old. If your gas ducted unit is running well, has not needed repairs, and is comfortably within its expected life, replacing it early means throwing away a functioning asset to chase a $200 to $450 annual saving. On that arithmetic the payback runs long, and the money is usually better spent on draught sealing and ceiling insulation, which reduce the bill under either system and cost a fraction as much.

The second case is a household staying on gas for other appliances. If you are keeping gas cooking and gas hot water regardless, the daily supply charge is being paid anyway, and one of the larger arguments for changing the heating disappears. In that situation the sensible plan is to sequence the changeover so that heating goes last, or goes at the same time as the hot water, so the connection can actually be dropped.

The third is timing. Peak heating season runs June to August, which is exactly when every heating contractor in Melbourne is booked out and every furnace decides to fail. Choosing a system in the middle of that is choosing on who can attend tomorrow rather than on merit. If your furnace is old but working, assess it in autumn and make a considered decision.

The fourth is a genuinely large, poorly insulated house where the heating load is high and the electrical supply is limited. That is not a reason to stay on gas forever, but it is a reason to fix the building fabric and the switchboard first rather than fitting a large electric heating system to a house that leaks.

Most households do not electrify everything in one weekend, and the order genuinely matters to what it costs.

Seal the draughts first, because it is the cheapest thing on the list and it reduces the capacity you need from whatever heater you end up buying. Fix the ceiling insulation second, for the same reason and because it pays back again every summer. Both work with your current gas furnace, so nothing is wasted if the changeover is still two years away.

Change the heater third, once the house holds heat, so the new system can be sized for the improved building rather than the leaky one. Sizing to a draughty house means paying for capacity you will not need afterwards, and an oversized system cycles instead of running steadily, which costs both efficiency and comfort.

Get the switchboard assessed once, not three times. If reverse cycle, a hot water heat pump, solar or an EV charger are all on the horizon, designing the board once to that whole plan is materially cheaper than modifying the same enclosure every time something new goes in. That is the most common avoidable cost we see across the western suburbs.

And book the work outside peak season. If you want an opinion on your specific house, including whether your ducts can be kept, get in touch. Pivot Trade Services holds REC 37223 and SAA accreditation S3962281, and every installation carries a 12 month workmanship guarantee on top of the manufacturer warranty.