In air conditioning, heat pump and reverse cycle mean the same thing: a system that both heats and cools by moving heat rather than generating it.
The name describes what the machine does. It pumps heat from where you do not want it to where you do. In summer it pumps heat out of your house. In winter it pumps heat from the outside air into your house.
Heat pump air conditioner, or heat pump hot water?
This trips people up, so it is worth separating.
- A heat pump air conditioner heats and cools the air in your home. That is what this page is about.
- A heat pump hot water system uses the same principle to heat water in a storage tank. It replaces an electric or gas hot water system, not an air conditioner.
Both are called heat pumps. They are different appliances and attract different rebates.
Why heat pumps are efficient
A bar heater turns one unit of electricity into one unit of heat. That is the ceiling for any resistive heater.
A heat pump does not convert electricity into heat. It uses electricity to run a compressor and a fan, and the heat itself comes free from the outside air. On the Australian market, reverse cycle air conditioners deliver roughly three to six units of heating or cooling for every unit of electricity they consume (energy.gov.au).
That is why several state governments now offer discounts for replacing gas heating with a reverse cycle system.
What forms do heat pump air conditioners come in?
Heat pump is a capability, not a shape. You can get it as:
- Split systems and multi-splits, the most common by far
- Ducted systems
- Cassette units set into the ceiling
- Floor consoles
- Some window and wall units
Performance in cold weather
Heating output falls as the outdoor temperature drops, and the outdoor unit periodically runs a short defrost cycle. Modern systems still work well below zero, but capacity and efficiency are lower than the headline figures suggest.
If you live somewhere with real winters, check the Zoned Energy Rating Label for the cold climate zone star rating rather than the average, and ask your installer for the rated heating capacity at low outdoor temperatures.
Do heat pumps dehumidify?
Yes, in cooling mode. Moisture condenses on the cold indoor coil and drains away, which is why an air conditioner produces water. Inverter models tend to dehumidify better than non-inverter models, because they run for longer at lower output rather than in short bursts.
Most systems also have a dedicated dry mode. Dry mode uses less energy than full cooling, but it is not a substitute for a dehumidifier and its ability to pull down humidity is limited.