Reverse-cycle air conditioning or gas heating?

A gas heater burns natural gas and passes the heat through a heat exchanger. A fan pushes the warm air into the room, or through ducts to vents around the house, and a flue carries the combustion gases outside. All the warmth comes from gas burned on the spot, and some of it always leaves with those flue gases.

A reverse-cycle air conditioner is a heat pump. In heating mode it absorbs heat from the outside air and releases it indoors; in summer it runs the other way. Because it moves heat rather than making it, the government's energy rating site says it can move three to five units of heat into a room for every unit of electricity. A bar or convection heater manages about one.

Installers call that ratio the coefficient of performance, or COP. It isn't fixed. The colder it is outside, the harder the outdoor unit works to find heat, so the ratio falls on a frosty night. That's why cold-weather heating figures matter more in Melbourne than brochure headlines.

The federal energy guide puts reverse-cycle air conditioners on the Australian market at 300% to 600% efficient. Ducted systems are less efficient than wall units, because a larger fan does the work and energy is lost through the ductwork. Even so, the guide rates ducted reverse-cycle as more cost-efficient than gas heating.

Heating is the half to focus on. Victorians typically use more energy for heating than cooling, so the Victorian Government suggests a unit with higher heating efficiency. The Zoned Energy Rating Label shows estimated yearly heating use in kWh, in red, and the Commonwealth's installer guide places Melbourne in the Cold zone.

Bills also depend on things no label sees: tariffs, insulation, draughts and how you run the system. The Victorian Government suggests 18°C to 20°C for heating, with every degree higher adding around 10% to the bill. Check your gas bill too: a fixed daily supply charge won't shrink because one appliance goes.

Gas ducted heating is quick and obvious. The burner fires, hot air pours from the floor vents, and once the thermostat is satisfied it shuts down until the house cools again. It's a heat you notice, in bursts.

Reverse-cycle feels different. Air from the outlet is warm rather than hot, and an inverter unit slows down instead of switching off, so the room holds an even temperature. It suits being left on at a sensible setting through the evening, not blasted for an hour when you get home. Warm air rises, so point the louvres down in heating mode.

On frosty mornings the outdoor unit collects ice and pauses heating for a few minutes to defrost. The indoor fan may stop and you might see steam outside, which catches people out the first time. Laverton's mean July minimum is 5.2 °C, below the 5.5 °C the energy rating guide uses for frosting conditions, so expect it in Melbourne's west.

Then there's summer. Laverton averages 27 days a year at or above 30 °C, when a gas heater does nothing and a reverse-cycle system becomes your cooling.

If you own and live in your home, nothing requires you to take out working gas heating. The Victorian Government says there's no requirement to switch gas space heating or cooking to electric, though it encourages homeowners to do it to lower their bills. Hot water is different: from 1 March 2027, a gas hot water appliance that breaks and can't be repaired must be replaced with an electric alternative.

Rentals have firmer rules. From 1 March 2027, when a rental's fixed heating fails and can't be repaired, it must be replaced with an energy-efficient fixed electric heating system with an outlet in the main living area. A working heater that meets the current minimum standard can stay. New rental agreements from that date also need efficient fixed cooling in the main living area, and Consumer Affairs Victoria notes one reverse-cycle air conditioner can satisfy both standards.

New homes are already heading there. From 1 January 2027, all new homes must be built all-electric.

A serviced, reliable gas ducted heater that warms the rooms you use isn't a problem to solve this week. If money is tight, keep it and plan the change for later. A common middle path is a reverse-cycle split in the living area: it carries most of the everyday heating and all the cooling, and the gas covers the bedrooms on the coldest nights.

If you keep gas, keep it serviced. Energy Safe Victoria recommends servicing gas heaters at least every two years by a qualified gasfitter, with a carbon monoxide test at the vents in every room for ducted heaters. Carbon monoxide can't be seen or smelt, so a heater that seems fine isn't proof it's safe.

Some things push the decision along. ESV says a change in flame colour means a qualified gasfitter must check the heater for carbon monoxide leakage, and that an old or long-unserviced heater is worth considering replacing. Open-flued heaters spill carbon monoxide more easily than other types, and weather-sealing a home around one may trap it inside.

Check whether your switchboard needs an upgrade before a reverse-cycle system goes in. ESV says a manufacturer's requirement for a dedicated circuit or safety switch must be followed, and an original board in a post-war Altona or Laverton home may have little spare room. Older homes can also have a small single-phase supply that needs upgrading, and three-phase makes sense when big loads such as a large ducted system and EV charging are planned together.

Size for heating first. For ducted systems, the Victorian Government recommends 1.1 to 1.4 kW of heating output for every 10 m² covered, depending on the home, with zones so you heat only the rooms in use. Older gas ducts often run under the floor, while ducted reverse-cycle usually sits in the roof with ceiling outlets, so existing ductwork needs checking, not assuming.

Three licences are involved. A licensed gasfitter disconnects and caps the old heater, because ESV says unlicensed gasfitting is illegal and potentially fatal. Installing a split system needs a refrigerant handling licence. The electrical work needs a licensed electrician, who must give you a Certificate of Electrical Safety.

Get us in when you want the whole picture from one visit. We're one local team for electrical, heating and cooling, so the same people look at the gas heater, the switchboard, the roof space and the outside walls, and explain what each option would need. That includes telling you when a sound gas heater is worth keeping for a few more winters.

You get the price before we start, as a fixed price for the agreed scope. Quotes are free and no-obligation, and our work carries a lifetime workmanship guarantee. If your heater has already failed, or a gasfitter has told you not to use it, mention that when you get in touch.