A two-bedroom unit and a four-bedroom family home need different air conditioning. Here's how we decide between split systems and ducted, and what size air conditioner each room needs.
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23The guide
Short answer: in the split system vs ducted decision, the house decides. A two-bedroom unit, a terrace or any home without usable roof space should have split systems, one in each room that needs it. A three or four-bedroom family home with roof space, where you want the bedrooms comfortable as well as the living area, is usually better off with zoned ducted air conditioning. Either way, the right size matters as much as the type, and there's a sizing guide by room further down.
Here's how we make the call on the houses we see around Newcastle, Maitland and Lake Macquarie.
A split system is a wall-mounted indoor unit in one room, connected by pipes to an outdoor unit. It cools and heats that one room, or an open-plan area it can reach. Most homes that have one have more than one.
Ducted air conditioning puts one larger indoor unit in the roof space, with ducts to a vent in the ceiling of each room. One outdoor unit, one controller, and with zoning you choose which rooms get air. Nothing hangs on the walls.
Both are reverse cycle, so both heat in winter as well.
A two-bedroom unit in Merewether or a terrace in Cooks Hill usually has no roof space worth the name. There may be a slab above, a strata building around it, or a skillion roof with a few centimetres of void. Ducted needs room for a unit and ducts above the ceiling, so in these homes the choice is made for you.
Splits also suit the way these homes get used. One unit in the living area and one in the main bedroom covers most of the year. You run the one you're in. A smaller home cools fast, so there's no reason to condition rooms nobody is sitting in.
What to watch in a unit or terrace:
Our split system installation page covers the job itself.
A four-bedroom home in Rutherford, Thornton or Cameron Park is a different problem. Kids' bedrooms at one end, a main bedroom at the other, an open-plan living and kitchen area in the middle. Covering that with splits takes four or five units, each on a wall, each with its own outdoor unit or a large multi-head unit outside.
That's where ducted earns its place. One system, vents in every room, and zones so you can cool the living area during the day and only the bedrooms at night. The house looks cleaner too, with no units on the walls. Most brick-and-tile homes from the last few decades have the roof space for it.
The honest catch is running cost. A ducted system cooling the whole house is conditioning far more space than one split in the lounge. Zoning is what keeps that in check, so we'd only recommend ducted with zones. If your family lives in one room all summer, splits will cost less to run.
Our ducted air conditioning page explains how we design the zones and what the install involves. If you're in Maitland, the air conditioning Maitland page covers the new estates from Thornton North to Lochinvar.
A three-bedroom house with roof space is the hard one. Our rule of thumb: if you want three or fewer rooms conditioned, go splits. If you want four or more, including bedrooms you sleep in on hot nights, price zoned ducted alongside them before you decide.
Capacity is measured in kilowatts (kW) of cooling. Too small and it runs flat out and never catches up on a hot afternoon. Too big and it cycles on and off and costs more to buy than it needs to.
As a starting point, the sizing guide General (formerly Fujitsu General) publishes for Australia allows about 0.15kW of cooling per square metre of floor, in these bands:
| Room size | Cooling capacity | Typical room |
|---|---|---|
| Up to 20 m² | 2.0 to 3.5kW | Small bedroom, study |
| 20 to 30 m² | 3.5 to 5.0kW | Larger bedroom, small living room |
| 30 to 45 m² | 5.0 to 7.0kW | Medium living area |
| 45 to 60 m² | 7.0 to 9.5kW | Large open-plan space |
| Over 60 m² | 9.5kW and up | Extra-large rooms |
Treat that as a starting point. High or raked ceilings, poor insulation, big west-facing windows and open-plan layouts all push the size up. A ducted system is sized for the whole house and its zones, which is why we do a room-by-room heat-load check at the quote visit instead of reading a number off a chart.
Wall split systems carry the Zoned Energy Rating Label, which gives star ratings for hot, average and cold climate zones. Ducted systems generally don't have to display the label, so ask for the model's seasonal efficiency figures and compare those.
If you're weighing up evaporative cooling as well, read evaporative cooling in Newcastle first. On the coast, we think reverse cycle wins.
23Questions
The house decides. For a unit, a terrace or any home without usable roof space, split systems are the better choice. For a three or four-bedroom family home with roof space, where you want every bedroom comfortable, zoned ducted air conditioning is usually the better fit.
It can be, because a ducted system cooling the whole house is conditioning far more space than a split cooling one room. Zoning closes off the rooms you aren't using, which narrows the gap. If you only ever cool the living room, a split will cost less to run.
A starting point is about 0.15kW of cooling capacity per square metre of floor. General (formerly Fujitsu General) suggests 2.0 to 3.5kW for a room up to 20 square metres and 7.0 to 9.5kW for a large open-plan space of 45 to 60 square metres. High ceilings, poor insulation, big windows and afternoon sun all push the size up.
Usually not. A ducted system needs room above the ceiling for the indoor unit and the ducts, so a flat-roofed terrace or an apartment with a slab above rarely suits it. Those homes are better served by split systems, one per room that needs it.
Once you want four or more rooms cooled and heated, and the house has roof space, it's worth pricing zoned ducted alongside the splits. Below that, splits nearly always make more sense for a Newcastle home.
Wall split systems carry the Zoned Energy Rating Label, which shows efficiency for hot, average and cold climate zones. Ducted systems generally don't have to display one, so ask for the model's seasonal efficiency figures when you compare quotes.
23Got a job?
Breakdown call-out: $140 in business hours, $220 after hours and on weekends, including the first half hour. Install quotes are free.