A 2.5 kW split system is suitable for most standard Australian bedrooms up to around 18 to 20 square metres with a standard 2.4-metre ceiling. For the majority of bedrooms in temperate climates, it is the most common and appropriate choice.
However, several factors can mean you need to step up to a 3.5 kW unit. These include a larger master bedroom with an ensuite or walk-in wardrobe, west-facing windows that get heavy afternoon sun, poor ceiling insulation, or a room in a hotter climate.
Oversizing a bedroom unit can cause it to short-cycle and leave the room feeling clammy, so it is worth getting the sizing right rather than simply going bigger.
Blue Mountains Air will calculate the right capacity for your specific room before recommending a unit.
