The compressor is the heart of an air conditioner. In a non-inverter (fixed-speed) unit it runs at one speed: full power or off. An inverter unit varies the compressor speed, a bit like a car that slows down instead of braking and accelerating all the time.
How each one holds the temperature
A fixed-speed aircon cools at full power until the room reaches the set temperature, switches the compressor off, waits for the room to warm up by a degree or two, then starts again. An inverter cools quickly at high speed, then slows right down and keeps running gently to hold the temperature steady.
| Inverter | Non-inverter (fixed speed) | |
|---|---|---|
| Electricity use | Lower in daily use — often 30% or more less | Higher; full power every time it runs |
| Temperature | Steady, within about half a degree | Swings up and down |
| Noise | Quieter once the room is cool | Louder start-stop cycles |
| Start-up current | Soft start — easier on solar and backup systems | Current spike every time the compressor starts |
| Purchase price | Higher | Lower |
| Best for | Bedrooms, lounges and offices used daily | Rooms used now and then |
Price difference by size
Current starting prices on our website, for the indoor and outdoor unit:
| Size | Fixed speed from | Inverter from |
|---|---|---|
| 9 000 BTU | R6,295 | R7,100 |
| 12 000 BTU | R7,010 | R7,910 |
| 18 000 BTU | R9,260 | R11,415 |
| 24 000 BTU | R13,845 | R16,450 |
Which should you buy?
If the room is used for several hours most days, buy an inverter: the lower running cost usually pays back the difference over a few years, and it is quieter and more comfortable. A fixed-speed unit is fine for a guest room, a boardroom used a few times a week, or when the upfront budget matters most.
Do inverter aircons really save electricity?
Yes, in rooms you cool or heat for several hours a day. The compressor runs at low speed most of the time instead of cycling at full power, so it usually uses noticeably less electricity than a fixed-speed unit of the same size. The saving is small if you only run the aircon for short periods.
Is an inverter aircon better for solar or a backup inverter?
Yes. It starts gently without a current spike and draws less power once the room is cool, so it is much easier for a solar or battery system to run. See running an aircon on solar.
Do inverter aircons last longer?
They avoid the constant start-stop cycles that wear a fixed-speed compressor, but they have more electronics. With regular cleaning and servicing both types commonly last ten years or more.