Quick answer: set your reverse cycle air conditioner between 18°C and 20°C for heating in winter. That’s the range recommended by energy.gov.au, and every degree above it can add 5–10% to your running costs. Here in the Northern Rivers, where winter mornings are crisp but days are mild, 18–20°C is almost always enough.
Why 18–20°C is the sweet spot
Your air conditioner doesn’t work like a kettle — setting it to 26°C won’t heat the room faster, it just tells the unit to keep working longer and harder. A reverse cycle system set to 19°C will reach a comfortable temperature just as quickly as one set to 26°C; the difference is that the second one keeps chewing through power long after you’re comfortable.
The maths adds up fast. If every degree above 20°C costs you an extra 5–10%, running your system at 24°C instead of 20°C could push your winter heating bill up by 20–40%. Over a Ballina winter, that’s real money for no real comfort gain.
Reverse cycle is still the cheapest heating going
A modern reverse cycle air conditioner is one of the most efficient ways to heat a home in Australia — for every kilowatt of electricity it uses, it can deliver three to five kilowatts of heat. That beats plug-in electric heaters by a wide margin. If you’re still dragging out an old fan heater on cold mornings, your ducted or split system set at 19°C will do the same job for a fraction of the cost.
Tips from our techs for cheaper winter heating
Heat the rooms you’re in, not the whole house. If you’ve got a ducted system with zoning, close off bedrooms during the day and living areas overnight. No zoning? Shut doors to unused rooms.
Use the timer. There’s no need to heat an empty house. Set the system to come on 20–30 minutes before you get up or get home.
Don’t blast it on arrival. Cranking the set point to maximum won’t warm you up faster. Set it to 19–20°C and give it a few minutes.
Aim the louvres down. Warm air rises, so direct the airflow toward the floor and let it circulate up through the room.
Check your filters. A clogged return air filter makes the unit work harder for the same result — more on that in our winter maintenance guide.
What about humidity?
Winter in the Northern Rivers still brings damp weather, and reverse cycle heating has a bonus: warming the air lowers its relative humidity, which helps keep condensation and mould at bay. If your home struggles with damp in the cooler months, running the system at a steady 18–20°C is better for the building (and your lungs) than short bursts of high heat. We’ve covered the mould and humidity problem in detail in a separate article.
Frequently asked questions
Is it cheaper to leave the air conditioner on all day in winter?
For most homes, no — use the timer so it runs only when you’re home and awake. The exception is very well-insulated homes on mild days, where maintaining a steady temperature can cost about the same as reheating from cold.
What temperature should I set at night?
Cooler is fine for sleeping — around 17–18°C, or off entirely with decent bedding. Many of our customers set the timer to switch off an hour after bedtime and back on before they wake.
Does 18–20°C apply to every home?
It’s the efficient range for most, but older folks, young kids, and health conditions can justify a degree or two more. Just know that each extra degree costs you.
Artisan Air Conditioning & Refrigeration has been installing, repairing and servicing air conditioning across Ballina, Lennox Head, Byron Bay and the Northern Rivers for over 20 years. Need help getting your system winter-ready? Give us a call.