What matters for ducted here?
Houses are where ducted fits
Separate houses were 73.1% of occupied homes in the Sunshine Coast council area at the 2021 Census. That's the ducted market, because the indoor unit and ducts need a roof space or subfloor to live in.
Designed for January, checked for July
Bureau of Meteorology averages at Sunshine Coast Airport give January a mean daily maximum of 29.1 degrees and July a mean daily minimum of 9.7. Size and zone for summer afternoons, then make sure the heating side copes with cool winter nights.
Humidity and oversizing
With afternoon humidity averaging 70% in January, a whole-house system that's too big is a real risk. Rinnai says oversizing causes short cycling and less effective dehumidification, which can leave a house cool but sticky.
No gas ducted to replace
The Queensland Government's list of natural gas distribution areas doesn't include the Sunshine Coast. So this is a reverse cycle decision from the start, not a question of reusing old gas heating ducts.
Building new in Aura
Aura, in Caloundra South, covers 2,310 hectares. On a new build there, agree the duct layout and return air grille with the builder before the ceilings go up.
How should a ducted system be zoned here?
Zoning lets parts of the house run on their own. Dampers in the ducts open and close to send air only where it's wanted, as ActronAir describes it.
Daikin's own example puts the bedrooms in one zone and the living areas in another. On the Coast that's a sensible starting plan: living areas through the afternoon, bedrooms at night.
ActronAir notes that a zoned system can only cool or heat at one time, with no more than a 4-degree difference between zones. Here that rarely bites, because most of the year you're cooling. It also warns that zoning without proper temperature sensors can cost more to run, so ask whether each zone gets its own sensor. Our page on zoning and controllers goes further.
What makes a ducted job bigger or smaller here?
One level and plenty of roof space is the simple version. Two storeys, a split-level block or a low, flat roof make the duct runs harder, and can mean two smaller systems instead of one.
Duct insulation is worth naming on the quote. The ACT Government's buyer's guide recommends R1.5 or better on ducting and warns that suppliers may not include it unless asked. It also points out that ducts through the ceiling cut into the ceiling insulation, so ask how that'll be made good.
Then there's power. The same guide says a large house may need a 3-phase upgrade for ducted, which your installer can confirm. The number of outlets and zones, and where the outdoor unit can sit out of the sea air, round out the list.
What you can do, and what's the installer's job
You can
- List the rooms you use in the afternoon and the ones you use at night. That's the start of your zone plan.
- Note which rooms get the western sun and which are always the last to cool.
- When it's in, wash the return air filter on the schedule in your manual.
- Stay out of the roof space. WorkSafe Victoria reports workers falling through plaster ceilings.
Leave to a licensed installer
- A room-by-room heat load and the duct design.
- Refrigerant work: a ducted system over 18kW, and any later refrigerant repair, needs a full RAC01 holder.
- The mechanical services work itself, under a QBCC licence.
- New circuits and any 3-phase connection, by a licensed electrician.
Questions for a ducted installer on the Coast
- How did you size it: a room-by-room heat load, or floor area?
- Which rooms are in each zone, and does each zone have its own temperature sensor?
- What's the insulation rating on the ducts?
- Where will the outdoor unit go, and what does the brand say about coastal placement?
- Does the house need a 3-phase upgrade?
- What's your RTA number and QBCC licence number?
What we'd do
Our take
We'd only accept a ducted design that comes from a room-by-room heat load, keeps the bedrooms in their own zone and has R1.5 or better duct insulation written into the quote. Near the beach, add a sheltered spot for the outdoor unit to that list. Then give it to a ducted specialist who lays out duct runs in Coast houses every week. Where we have installers like that, they see your job and only the one who takes it gets your contact details. If we don't, we say so.
