Split System Heating That Costs Less to Run

Every split system carries two ratings on the label, one for cooling and one for heating, and they are not the same. On most units the heating capacity is slightly higher than the cooling capacity, but the rated output also falls as the outside air gets colder because there is less heat available to collect.

That is why we quote against the heating load in a Melbourne winter rather than the cooling load in a Melbourne summer. For a well insulated 4 by 5 metre bedroom, 2.5 kW is usually right. A 6 by 7 metre open plan living and dining space with a raked ceiling and west facing glass is more likely 6 to 7.1 kW. Ceiling height, insulation, glazing and orientation all move that number, which is why we work from volume and construction, not floor area.

Warm air rises, which works against a high wall head unit. A good installation aims the airflow down and along the floor, so the room fills from the bottom rather than baking the ceiling. We look for a wall that lets the unit throw across the length of the room, not into a bulkhead or straight at a curtain.

The other constraint is the pipe run back to the outdoor unit. Short, direct runs perform better and cost less to install. Long runs through a roof space need extra refrigerant, more insulation on the pipework, and careful thought about oil return on vertical rises. We will always tell you when a preferred head position adds real money, and what the alternative costs.

A multi head system runs two to five indoor units off one outdoor unit. It looks tidier and saves wall space outside, which matters on the narrow side setbacks common in Newport and Seddon. The trade off is that all the indoor heads share one compressor, so they cannot run in heating and cooling at the same time, and if the outdoor unit fails every room loses its heating at once.

Separate single head systems cost more in outdoor units and pipework but fail independently, run at their best efficiency in each room, and are simpler and cheaper to repair. Our general advice is to use singles where there is room for the outdoor units, and multis where there genuinely is not.

On damp mornings below about 7 degrees, frost forms on the outdoor coil. The system periodically reverses to melt it, which is why the outdoor unit steams and the indoor fan stops for a few minutes. This is designed behaviour, not a fault, and the indoor fan pausing is the unit avoiding blowing cold air at you.

Frequent, long defrost cycles are a different story. They usually point at an outdoor unit sited where it cannot breathe, a fan or sensor problem, or low refrigerant charge. If your system spends more time defrosting than heating, it is worth a service call rather than a bigger thermostat setting.

Two licences apply to every split system install in Victoria. Refrigerant handling requires an ARC licence, and the electrical connection must be done by a licensed electrician who issues a Certificate of Electrical Safety. Pivot holds REC 37223 and does both parts in house, so there is no waiting on a second trade to energise the unit.

A correct install includes pressure testing and vacuum before the refrigerant is released, a properly graded and terminated condensate drain, sealed wall penetrations, and a commissioning check that measures the temperature split across the indoor coil. Ask for those. A unit that has been gassed up without a vacuum will work for a season and then start giving you trouble.