Cairns facts that change the install
Humidity through the wet
Average afternoon humidity at the Bureau of Meteorology's Cairns station peaks at 71% in February, with a dew point of 23.6 degrees. Rinnai says oversized systems short cycle and dehumidify less effectively, so going a size up to be safe can leave a room cool but clammy.
A tropical house, sealed in places
The Queensland Government's zone 1 advice is to design for breezes and shade with wide eaves, but to insulate and seal any room that's air conditioned. In practice that means choosing which rooms get closed up and cooled, and which stay open to the breeze.
Apartments and rentals
15.7% of occupied dwellings in the Cairns council area were flats or apartments at the 2021 Census, and 35.0% were rented.
Floods
Cyclone Jasper's December 2023 flood was the Barron River's worst since records began in 1915. For flood-prone homes, Get Ready Queensland's list of resilience steps includes putting air conditioner units and switchboards above the flood level.
Salt near the coast
Daikin says all its outdoor coils carry a 'Blue Fin' anti-corrosion treatment, and that maintenance and positioning, as set out in the installation manual, still matter.
Sizing for a Cairns room
Ask for a heat load calculation. Mitsubishi Electric calls one essential, because climate, orientation, insulation, windows, building materials and ceiling height all change the answer.
Rinnai's starting points, a 2.5 kW unit for spaces up to roughly 20 square metres and 3.5 kW up to about 30, help you sanity-check a quote. They don't replace the visit.
Tropical rooms lose cool air through louvres, gaps and uninsulated ceilings. Sealing and insulating first can bring the size down: ActronAir says a well insulated home likely won't need as much capacity as a poorly insulated one.
Apartments, rentals and approvals
In a unit block, the outdoor unit usually goes on a balcony, an external wall or a shared area, and the body corporate will want a say. Get the approval in writing before you book, and read our apartments and strata page for what to ask.
If you rent, the owner decides. Tell your property manager what you need and which rooms matter most.
What makes a Cairns install bigger or smaller
A back-to-back split on a ground-floor wall is the simple version. Raising the outdoor unit above flood or storm tide height, running pipes down from a high-set house, or mounting on an apartment balcony or wall all add work.
Electrical work grows if the switchboard has no room for the dedicated circuit each unit needs; Mitsubishi Electric says a non-dedicated supply may cause overheating or fire. And several rooms means a choice between separate splits, a multi-split, with one outdoor unit for a small balcony, and ducted. Our main installation page has the full job.
Questions for a Cairns installer
- What size did you work out, and how did you allow for humidity?
- Which rooms should I seal up, and what insulation would help?
- Where will the outdoor unit go, and how loud is it at night for the neighbours?
- Does this model have a coil coating, and what does the warranty say about sea air?
- Have you checked the flood or storm tide level for this address?
Before anyone quotes
You can
- Get body corporate or landlord approval in writing first.
- List the rooms you'll close up and cool.
- Compare the corrosion terms in the warranties of the models you're quoted.
Leave to a licensed installer
- Heat load and sizing.
- Raising and fixing the outdoor unit.
- Refrigerant pipework and commissioning, and circuits by a licensed electrician.
Who's licensed to install
Installation is mechanical services work, so in Queensland it needs a QBCC licence at any value. The wiring needs an Electrical Safety Office licence, and any multi-split, or a split over 18kW, needs an ARC RAC01 holder rather than RSS03.
Licence-checked Cairns installers who specialise in that kind of system see your install, where we have them near you. If no Cairns installer takes it within 48 hours, installers elsewhere in Queensland may see it as well. Your contact details go to just one of them: whoever takes the job. Our Cairns page covers the city's climate in more detail.
What we'd do
What we'd do
We'd get a heat load done with the humidity in mind and choose the size it gives, not one up. We'd seal and insulate the rooms being cooled, put the outdoor unit on the most sheltered side that still breathes and above any flood or storm tide level, and in a unit block we'd have the body corporate's yes in writing before booking.
