If you want app control on the air conditioner you already own, you almost never need a new thermostat. It comes down to one of three things: a wifi module made for your unit, a small infrared controller that copies your handpiece, or a smart plug if the thing actually plugs into a power point. Which one you can use is decided by the aircon, not by the app.
Worth clearing up early. The wall-mounted “smart thermostats” marketed so hard online are built for central ducted systems wired back to a low voltage thermostat cable. A typical Aussie wall-hung split has no such cable, so the gear sold here for retrofitting smarts is a little box that sits in the room, not a thermostat you swap out.
Three ways to add smart control
- The manufacturer’s own wifi kit: most current splits either ship with wifi built in or take a matching module that clips into the indoor unit. Best option by a fair margin, because it talks to the unit properly and the app knows the real running state. If your split is only a few years old, check the model first. You may already have it unused.
- An add-on infrared controller: a small box on a wall or shelf that sends the same infrared codes your handpiece does. It suits any unit driven by an IR remote, which covers most wall-hung splits in the country, and it works on units far too old to have wifi of their own.
- A smart plug: only relevant if the unit runs off a normal power point, so portables and some window boxes. Useless for a hardwired split, and it has a catch covered below.
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Add-on infrared controllers are easy enough to find here, the Sensibo Sky being one of the common ones. Whatever you look at, check it against your exact indoor unit first, for the reasons below.
What scheduling and geofencing actually save you
The honest version is not the one the marketing leads with. The biggest lever on your running cost is the temperature you set, not the cleverness of the schedule. The Australian Government’s YourHome guide puts it plainly: “Each extra degree of heating or cooling increases the system’s energy use by about 5 to 10 per cent”, and it recommends you “Set the thermostat to 18 to 20 degrees C in winter and 25 to 27 degrees C in summer”. Dragging a room down to 21 instead of holding 25 costs you more than any schedule will claw back.
Scheduling earns its keep on a different problem: the unit running when nobody benefits. Cooling an empty house all afternoon, or heating a bedroom from 6am when the first person is up at 7.30. Geofencing, where the app starts things as you head home, is comfort rather than savings, since you still pay to cool the house. Be wary of any percentage saving quoted at you, because it depends entirely on the habits it replaces.
Compatibility is decided by your indoor unit
Brand-level compatibility is close to meaningless, because remote protocols change across model years within the same brand. Get the model number off the label on the indoor unit, usually on the side of the case, and check it against the controller maker’s list.
Three situations where an infrared add-on will not do the job:
- Splits with a hardwired wall controller and no IR handpiece: there is nothing for the add-on to imitate.
- Ducted systems: these run off a proprietary wired touchpad, often tied into zone motors. The path is the manufacturer’s wifi upgrade or a controller swap, and that is installer work.
- Anything without line of sight: infrared has to reach the receiver on the indoor unit. Around a corner will not fly.
Infrared is also one way. The box sends commands out but has no idea what the aircon is actually doing, so if somebody picks up the handpiece and switches it off, the app may still report it as running. Better add-ons work around this with their own temperature sensor, but expect some drift.
Where DIY stops
The line is simple. Plugging something into an existing power point, or sticking an infrared box on the wall, is yours to do. Anything connecting into the aircon’s supply, its isolator or the switchboard is electrical work. Energy Safe Victoria is blunt about it: “If you are planning to have electrical installation work done, you must engage a registered electrical contractor (REC). They will send a licensed and qualified electrician to do the work to the required standards.” Every state and territory has a regulator saying much the same.
Manufacturer wifi modules sit in an awkward middle, since fitting one means opening the indoor unit’s case, which can put your warranty in question. Cheapest answer is to have it fitted at the next service, when the cover is off anyway.
That smart plug catch, since we are here: a plug only cuts and restores power. Whether the aircon comes back on depends on whether that unit resumes its previous settings afterwards, and plenty do not. They sit in standby waiting for a remote press. Test it before building a schedule.
So is it worth it?
Worth doing if your hours are unpredictable, if you get to work and cannot remember whether you left it running, if you are managing a rental or holiday place, or if you want to check on an elderly parent’s heating in a cold snap. Less worth it if you are home to a routine and already sit in that 25 to 27 degree band. Before spending anything, look properly at the timer built into your handpiece. Most people have never set it, and for a predictable week it does most of what an app schedule would, for free.
