Using Your Air Conditioner for Heating in Brisbane Winter

Can You Use Your Air Conditioner for Heating?

Yes — if you have a reverse cycle air conditioner (and most Brisbane homes do), your AC doubles as a heater. Reverse cycle systems use a heat pump to extract warmth from outdoor air and transfer it inside, making them the most energy-efficient way to heat your home in Brisbane’s mild winters.

How Reverse Cycle Heating Works

In cooling mode, your AC removes heat from inside and pumps it outside. In heating mode, it does the opposite — extracting heat from the outdoor air (even when it feels cold) and pumping it indoors. This process is 3-6 times more efficient than portable electric heaters because it moves heat rather than generating it.

Brisbane winters rarely drop below 5°C overnight, which means reverse cycle systems operate at peak efficiency here. In colder southern cities, heat pumps can struggle below 0°C, but that’s rarely an issue in Southeast Queensland.

Running Costs: AC Heating vs Other Options

Reverse cycle AC heating costs roughly one-third of what a portable electric heater costs. Over a Brisbane winter (May-August), that difference adds up to $150-$200 in savings.

Best Temperature Setting for Winter

Set your air conditioner to 20-22°C in heating mode for the best balance of comfort and efficiency. Every degree above 20°C adds approximately 10% to your running costs. At 22°C, most people feel comfortably warm without overheating.

Use the “Auto” fan setting in heating mode — it starts on high to warm the room quickly, then drops to low to maintain temperature quietly.

Tips for Efficient AC Heating in Brisbane

• Use a timer — Set your AC to turn on 30 minutes before you wake up rather than running all night
• Close doors and curtains — Keep warm air in the rooms you’re using, close curtains at sunset to insulate windows
• Set the swing vane downward — Hot air rises, so direct the airflow downward to heat the living space rather than the ceiling
• Use zone control — If you have ducted AC, only heat the rooms you’re actually using
• Don’t crank it up — Setting your AC to 28°C won’t heat the room faster, it just runs longer and costs more. Set to 20-22°C and let the inverter do its job
• Get a winter service — A pre-winter service ensures your system heats efficiently. Dirty filters and low refrigerant reduce heating performance significantly

When AC Heating Doesn’t Work Well

If your reverse cycle AC struggles to heat in winter, common causes include:

• Dirty filters — Restricted airflow means the system can’t distribute warm air effectively
• Low refrigerant — A gas leak reduces the heat pump’s ability to extract warmth from outdoor air
• Undersized unit — A unit too small for the room will run constantly without reaching the set temperature
• Defrost cycle issues — On cold mornings, the outdoor unit defrosts periodically (this is normal), but if it defrosts excessively, there may be a fault

Pre-Winter AC Service

Book a service before winter to ensure your system heats efficiently. Our technicians check refrigerant levels, clean coils, test heating mode performance, and ensure everything is ready for the cooler months.

Call Sun City Air on 07 3283 5566 or book a winter service online.

Related: AC servicing Brisbane | Service costs | How to save money on AC