Replacing or installing a ducted gas heating system is one of the bigger household investments a Melbourne homeowner will make. When a heater breaks down mid-winter, the last thing you want is vague estimates and a final invoice that looks nothing like the original quote.
So what does ducted gas heating actually cost in Melbourne right now?
The honest answer is that it depends on the scope of the work. Here’s a realistic breakdown.
The Broad Price Ranges
For a straightforward unit swap – removing your old heater and connecting a new one of similar size to your existing ductwork and gas line – a standard ducted heating replacement typically falls between $2,200 and $4,500.
If you’re installing a completely new system from scratch, or if your existing ductwork has degraded and needs replacing, the total generally runs between $4,500 and $8,000. For large, multi-storey homes with complex zoning requirements and premium 6-star units, costs can extend beyond $9,000.
To understand where your home sits within those ranges, you need to look at the specific factors that drive the price up or down.
Unit Replacement vs. Full System Installation
The single biggest factor in any ducted heating quote is whether a contractor can use your existing infrastructure or whether it all needs to come out.
A unit replacement involves disconnecting your old heater and connecting a new one to your existing gas line, electrical connection, thermostat, and ductwork. Because the ductwork is already in place, labour costs are significantly lower and most jobs can be completed in half a day.
A full installation is a different job entirely. If your gas ducted heating system is 20 years old, there’s a strong chance the ductwork is in poor condition. Flexible ducting collapses over time, plastic linings tear, and rodents frequently chew through insulation. Connecting a new, high-efficiency unit to damaged ductwork means pumping expensive warm air straight into your roof cavity rather than into your rooms. In these cases, the old ducting has to be stripped out and replaced entirely – more materials, more time, and a higher final cost.
Energy Star Ratings: Upfront Price vs. Running Costs
When choosing a new unit, you’ll find options rated anywhere from 3 stars to 6 stars for energy efficiency. The star rating has a significant impact on the purchase price and an equally significant impact on what you’ll pay to run the system year on year.
A 3-star unit is the most affordable upfront. These use simpler technology, heat reliably, and will absolutely keep your house warm through a Melbourne winter. They consume more gas to do it, but for a rental property or a home you plan to sell within the next few years, they’re a sensible choice.
A 6-star unit costs considerably more to purchase. These use condensing technology that captures heat from exhaust gases – heat that would otherwise be lost through the flue – and recycles it back into your home. The upfront cost is higher, but a 6-star unit uses far less gas per hour of operation. For a homeowner planning to stay in the property for the next 10 to 15 years, the reduction in annual running costs typically covers the difference in purchase price.
A quality installer will help you run those numbers before you commit to a unit.
Home Size and Heating Capacity
Heaters are sized by kilowatt output, and getting that sizing right matters more than most homeowners realise.
A compact three-bedroom home might need a 14kW unit to heat comfortably. A large two-storey home with multiple living zones might require 30kW or more. If a contractor quotes you a unit that’s too small for your floor plan, the heater will run continuously trying to reach the set temperature – wearing out internal components ahead of time and driving your gas bill up. If the unit is too large, it will short-cycle, switching on and off rapidly, which is just as damaging to the machinery.
A proper quote includes room measurements and an output calculation – not just a unit from a standard price list.
Zoning: Comfort vs. Cost
Installing zones allows you to divide your home into independently controlled areas – a day zone for living areas and a night zone for bedrooms, for example. You only heat the rooms you’re using, which reduces running costs considerably over time.
That said, zoning increases the initial installation cost. It requires motorised dampers inside the ductwork to control airflow, additional low-voltage wiring, and a more advanced wall controller. Upgrading from a basic manual switch to a smart programmable touchscreen adds a few hundred dollars to the quote. For most homeowners planning a long-term stay, it’s money well spent.
Gas Line and Infrastructure Upgrades
Modern efficient gas appliances often require a higher volume of fuel than the units they’re replacing. During an inspection, a licensed gasfitter checks the size of the gas pipe running from your street meter to the heater location. If that pipe is too narrow, the new unit will be starved of fuel and fail to ignite reliably.
Upgrading a gas line involves running new copper or composite pipe under the home or through the roof space. It’s a strict compliance requirement, not an optional extra, and it will affect the total cost of the job if your existing infrastructure isn’t up to the task.
Repair vs. Replace: Getting the Call Right
Sometimes a repair is the smarter financial move. A relatively modern unit with a faulty ignition sensor or a blown capacitor can often be back running for a few hundred dollars.
But there are situations where spending money on a repair is a poor decision. If a heater is more than 15 years old and the main fan motor has burnt out, replacement parts are often expensive or no longer available. More critically, if an inspection reveals a cracked heat exchanger, the unit must be taken out of service immediately. A cracked heat exchanger allows carbon monoxide to enter the air stream circulating through your home. Heat exchangers cannot be safely patched – replacement is the only legal and safe option.
Putting money into a system that’s in that condition is a false economy. It’s also the natural point at which to consider a quality replacement unit from brands like Braemar, Brivis, or Bonaire.
What to Watch for in a Low Quote
When gathering quotes, you may find one price that sits noticeably below the others. Look closely at what that quote actually includes.
Contractors who price unusually low often do so by using cheap imported ductwork with thin insulation – meaning heat escapes into the roof before it reaches your vents. Others skip replacing old roof flashing, which creates a high risk of water ingress during the next heavy rainstorm. Some exclude removal and disposal of the old unit entirely.
The most important thing to check: does the quote include a compliance certificate from the Victorian Building Authority? This certificate is your legal proof that the installation was completed safely and to the required state standards. No certificate means no proof the job was done correctly – and potential liability if something goes wrong down the track.
What a Reputable Quote Should Look Like
A trustworthy ducted heating quote starts with a licensed plumber inspecting your home – checking existing ductwork, measuring your rooms, and assessing your gas line sizing before any number is put on paper.
From that inspection, you should receive a fixed price that covers the unit, all labour, removal and disposal of the old system, and compliance certification. No surprise fees for extra piping, no disposal charges added on completion, no hidden costs.
Every installation should be tested for carbon monoxide before the technician leaves – and backed by a workmanship warranty that gives you confidence the job was done to last.
A warm home at a price that doesn’t change between quote and invoice. That’s what a quality installation looks like.
