What a Sydney house asks of a ducted system
The west is hotter, for longer
Sydney's CBD averages 15 days a year above 30 degrees. Liverpool averages 41 and Penrith 67, because the sea breeze that cools the eastern suburbs doesn't make it 9 km inland.
And the top end is where capacity drops
AdaptNSW says Western Sydney averages 10 to 20 days a year above 35 degrees. ActronAir says a system loses cooling capacity above 35, with a 14 kW unit falling to 10 or 12 kW in its example.
Frosty nights to the north-west and south-west
Richmond averages 17 nights a year below zero, and Camden Airport's July mean minimum is 3.0 degrees. In those suburbs, a ducted system spends months as the heater.
Houses, not units
Separate houses were 55.8% of Greater Sydney's homes at the 2021 Census and apartments 30.7%. Ducted is mainly a house job here; in a unit, ask about a multi-split instead.
A ducted quote in the east and in the west
| Eastern and coastal suburbs | Western suburbs | |
|---|---|---|
| Climate zone | Zone 5, warm temperate | Zone 6, mild temperate |
| Summer heat | Sea breezes help; much of the region sees fewer than 10 days a year above 35 degrees | No sea breeze relief; 10 to 20 days a year above 35 degrees |
| Humidity | Higher: January afternoons average 60% at Observatory Hill | Lower: January afternoons average 47% at Penrith |
| Winter | Mild: Observatory Hill has never recorded a frost | Cold nights: Camden Airport's July mean minimum is 3.0 degrees |
| Push for on the quote | No oversizing, so it dries the air, and salt protection near the water | Capacity on the hottest afternoons, and a heating figure in writing |
Zoning a Sydney house
Zoning splits the house into areas that are heated or cooled separately, with dampers in the ductwork opening and closing, as ActronAir explains. In a western Sydney house, it often pays to zone the sun-baked side apart from the rest, as well as bedrooms from living areas.
ActronAir also says the whole system runs in one mode at a time, heating or cooling, with no more than a 4-degree difference between zones. Know that before you plan around an upstairs that's always warmer than downstairs.
What makes a Sydney ducted job bigger
Coming off gas ducted heating. The ACT Government guide says old gas ducts can't be reused for reverse cycle because they're too narrow and may have age-related problems, so allow for new ducting throughout.
The roof space. A low or cramped roof makes duct runs harder. The crew needs crawl boards and light up there, because WorkSafe Victoria reports workers falling through plaster ceilings.
The power. The ACT guide says a ducted system in a large house may need 3-phase power, and your installer can confirm it.
Duct insulation. The ACT guide recommends at least R1.5 on the ducting and says suppliers may not include it by default. Under a western Sydney roof in January, ask for it by name.
Our national ducted air conditioning page covers the install step by step.
Signing at the kitchen table
Ducted is a big decision, and it's usually quoted at home. NSW Government guidance says that if a supplier you asked to quote starts negotiating a deal on that visit, the agreement can be unsolicited, which brings a 10 business day cooling-off period. If they leave the quote and you get back to them later to accept it, it isn't. Our cooling-off guide explains your rights.
Your part, and the ducted installer's
You can
- List the rooms you use on summer afternoons and winter nights. That's your zone plan.
- Note which rooms face west and which are always cold.
- Once it's running, clean the return air filter as your manual says.
Leave to a licensed installer
- The room-by-room heat load and the duct layout.
- Everything in the roof space.
- Refrigerant pipework, new circuits and any 3-phase work.
Before you sign a Sydney ducted quote
- Did you size this for afternoons above 35 degrees, and what's the capacity then?
- What heating output will it give on a frosty western Sydney morning?
- How many zones, and which rooms are in each?
- What insulation rating is on the ducts?
- Can any of the existing ductwork stay, or is it all new?
- Does my switchboard or supply need an upgrade?
What we'd do
What we'd do
We'd ask every installer for a room-by-room heat load that names the suburb's climate, not one worked out from floor area alone. Out west, we'd want the hot-afternoon capacity and the heating output in writing; near the coast, we'd resist oversizing. We'd take the quote away and decide in our own time, then hand the job to a ducted specialist who designs duct runs for Sydney houses every week.
