However, if you live in the southern states of Australia, it’s certainly not summery conditions all year round. During the frosty winter months, a heater is definitely a necessity. In this case, your reverse cycle system extracts heat from the air outside, even in winter, and uses a refrigerant to heat the air through a condenser, then distributes the warm air inside. (After being passed through a filter of course). Reverse cycle heaters have a defrost function meaning they can still work effectively in temperatures below freezing. This is a much more energy efficient process than using a conventional or gas heater, which operates by creating heat.