What a Melbourne house asks of a ducted system
Plenty of ducts already, few of them cooling
In the 2021 JWS survey for the Victorian Government, 40% of gas-area home owners mostly heated with heating-only gas ducted systems, and 18% had ducted reverse cycle. A lot of Melbourne houses have ducts in the roof or under the floor, but nothing cooling them.
Hot spells are more frequent
Occasional days of extreme heat have become more frequent in Melbourne since 2005. Summer heat isn't even across the city either: Viewbank, in the north-east, averages 28.2 degrees in January, so a house out there needs more cooling headroom than one by the bay.
Winter still sets the size
July nights average 5.8 degrees at Melbourne Airport and 5.0 at Laverton, on Bureau of Meteorology figures. A ducted system sized only for summer can leave a Melbourne house cold in winter, so ask for both heating and cooling capacities.
The power to run it
The ACT Government's guide says a large ducted system may need a 3-phase power upgrade, and your installer can confirm it. CitiPower runs the network in the CBD and inner suburbs, and AusNet across Melbourne's north and east.
Coming off gas ducted heating
Expect more work than a heater swap. The ACT Government's guide says gas ducts are too narrow for reverse cycle and may have age-related problems, so you're looking at new ductwork, a new indoor unit in the roof or under the floor, and an outdoor unit. A gasfitter disconnects the old heater.
If you'd rather keep gas for heating, add-on cooling uses the existing ducts instead. Rinnai says it only works with a compatible heater and suitable ducting, so have that checked first. Our Melbourne ducted heating page weighs up the options.
Zoning a Melbourne home
Daikin's example zoning puts the bedrooms in one zone and the living areas in another, so you can heat the living room in the evening and only the bedrooms overnight. Solar Victoria's advice is to heat or cool only the areas you're using.
ActronAir says all zones run in the same mode, heating or cooling, with no more than a 4-degree difference between them, and warns that zoning without proper temperature sensors can be less efficient. The national ducted air conditioning page covers the install step by step.
VEU and rentals
A ducted reverse cycle system can get a VEU discount through an accredited provider, but the program is voluntary and the rules set a floor: for a Melbourne ducted job through VEU, the minimum co-payment from 30 September 2026 is $3,000 including GST, and it can't be paid back to you in cash or extras.
For a rental, Consumer Affairs Victoria says a ducted unit needs a Total Cooling Seasonal Performance Factor of 3.8 or above to meet the cooling standard, and a ducted electric heater replacing a failed main heater needs a Heating Seasonal Performance Factor of 3.2 or more.
What to ask about a Melbourne ducted quote
- What heating capacity does this give on a July night, and how much cooling does it lose above 35 degrees?
- How many zones, and does each have its own temperature sensor?
- Are all the ducts new, and what's their insulation rating?
- Will the house need a 3-phase upgrade?
- If we want a VEU discount, which accredited provider would create the certificate?
Your part, and the installer's
You can
- Decide which rooms belong together in a zone.
- Tell the installer which rooms bake in summer and which stay cold in winter.
- Clean the return air filter on the manual's schedule once it's running.
Leave to a licensed installer
- The room-by-room heat load and duct design.
- Everything in the roof space or under the floor.
- Refrigerant, electrical and any 3-phase work.
- Disconnecting and removing an old gas heater.
What we'd do
Our take for a Melbourne house
We'd only compare ducted quotes that show the heating capacity for a July night and how the cooling holds up past 35 degrees, with the bedrooms zoned apart from the living areas. Coming off gas, we'd expect new ducts and plan around it. Then we'd give the job to a ducted specialist who designs duct runs every week, because the ducts decide how well the whole house heats and cools.
