Inverter or non-inverter: which aircon should you choose?
The inverter question comes up in almost every installation, and the answer is less about fashion than about how you will use the unit. This guide explains what an inverter actually changes.
What an inverter actually does
A non-inverter unit runs its compressor at one speed: on, or off. It switches on, cools the room, switches off, then switches on again when the temperature drifts. An inverter unit can vary the compressor speed, so it can run slowly and continuously instead of working in bursts.
That single difference explains most of the rest. Running slowly and steadily uses less power than starting and stopping, holds the temperature within a narrower band, and is quieter because the compressor is not at full speed for most of its life.
Where the difference shows in a Johannesburg summer
On a mild day the two units feel similar. The difference shows in a Highveld January, when a non-inverter unit is starting and stopping all afternoon and an inverter is sitting at a low, steady speed. That is where the running cost, the noise and the comfort separate.
It also shows over time. A compressor that starts and stops hundreds of times a season does more work than one that turns slowly for the same hours, and the electrical draw at startup is the heaviest moment in its cycle.
What the difference costs you over time
Two units of the same capacity, one inverter and one not, will do the same job on a mild day. Over a summer of nightly use the inverter runs at low speed for long stretches while the other starts and stops, and the difference shows in how the unit sounds, how steady the room temperature feels and what the compressor has been through.
There is also the electrical side. A unit draws its heaviest current as the compressor starts, so a unit that starts less often is gentler on the circuit it sits on. Add that to the comfort of a temperature that does not swing and the case is usually clear for a room that is used every night.
- How often the unit actually runs through the season.
- Whether the room is occupied every day or only occasionally.
- Whether the circuit already carries a heavy load.
- Whether the unit will also be used for heating in winter.
When a non-inverter still makes sense
A non-inverter unit is usually less expensive to buy, and where a unit is used occasionally, or where the budget is genuinely tight, that can be the right call. It is a straightforward machine and there is less to go wrong.
The sensible test is how the room is used. A bedroom unit that runs every summer night is where an inverter earns its price, while a spare-room unit switched on a few times a year may never recover the difference. Our sizing guide covers the capacity question that comes first.
What to ask
Ask which unit is being quoted and whether it is an inverter, and ask for the make and model in writing. Ask too what warranty comes with the unit and with the installation, because the two are not the same promise.
Finally, ask how the unit was sized. An inverter that is too large for the room still short cycles, and the efficiency argument for it quietly disappears. Aircon installation covers what the installation itself involves.
Frequently asked questions
Is an inverter always better?
For a unit that runs often, usually yes, because steady running uses less power than starting and stopping. For a unit used a few times a year, the extra purchase price may never be recovered.
Are inverter units harder to repair?
They have more electronics, so a fault can be a board rather than a mechanical part. Ask about the warranty on the unit before you choose.
Do inverters need different servicing?
No. The filter and coil still load up with dust, so the service rhythm is the same. Aircon servicing covers what a clean and check includes.
Does an inverter help with load shedding?
It draws less power overall because it is not starting and stopping, so it is gentler on a supply that is already carrying a lot, and it is easier to run from backup. How that shows on a bill depends on how the unit is used.