How much cooling do you need
As a rough guide, 7000 to 9000 BTU suits a bedroom or a small office, 12000 BTU a typical living room, and 14000 BTU and above a large open plan space or a workshop. An undersized unit runs flat out on a hot day and never catches up. An oversized one cools the air quickly but switches off before it has taken much moisture out, so the room can feel clammy.
Monobloc or portable split
Most portable air conditioners are monoblocs: everything is in one cabinet and the hot air leaves through a hose to a window. A portable split puts the noisy, hot half in a small outdoor unit joined by a flexible pipe, so the room stays quieter and cools better, though the pipe needs a gap in a window or door. Heat pump models also warm the room in cooler months.
Venting, drainage and noise
Every portable air conditioner needs somewhere to send its hot air, usually through a window kit that seals the gap around the hose. Many models evaporate the water they collect and send it out with the exhaust, while others fill a tank or need a drain hose in humid weather. Noise is quoted in decibels (dB), and every 10 dB sounds roughly twice as loud, so a few decibels matter in a bedroom.
