The number on the quote should come from the room, not the catalogue. We ask about floor area, ceiling height, which way the windows face, whether the ceiling is insulated and whether the room opens onto a hallway or a second living area. A 3.5 kW unit that is perfect for a south-facing bedroom in Coburg will struggle in a west-facing upstairs room in a two-storey estate home with a black roof.
The mistake we correct most often is going one size up to be safe. An oversized inverter unit reaches temperature quickly, then spends its life short-cycling, which is noisier, less efficient and worse at removing humidity. With WindFree in particular the unit needs to settle into its gentle mode, and it only does that when it is sized to hold the room rather than blast it.
The second mistake is sizing for summer only. Samsung’s wall units are reverse cycle, and in Melbourne they will heat far more hours than they cool. We size for the winter load in older, draughtier homes — period weatherboards, unrenovated brick veneers — and confirm the unit still has headroom for a February heatwave.
If you want to work through it yourself first, our split system sizing guide walks through the room-by-room maths. Then call, tell the office the rooms, and they will give you a free estimate on the spot.