Coway Airmega 400 True HEPA Smart Air Purifier (White)

The Airmega 400 pulls air in through both sides, each through a washable pre-filter and a Max2 filter (activated carbon plus True HEPA). Coway rates it for 1,560 square feet at two air changes an hour. A particle sensor shows the air quality as a coloured light, and the auto, eco and sleep modes set the fan on their own; a light sensor turns it down in a dark room.

It suits a big living space or an open floor plan. For one bedroom it is more machine than you need. This is the plain 400, not the 400S: the S adds Wi-Fi and the app, and both take the same filters.

Worth knowing No Wi-Fi or app on this model. It takes two Max2 filters, which Coway says last about 6 to 12 months, so replacement sets are a running cost.