Monoblock air conditioners compared

A monoblock houses the compressor, evaporator and condenser in a single casing. The waste heat goes out through the window via an exhaust hose (usually 13–15 cm in diameter). Because the unit blows room air outside, it creates slight negative pressure – warm air flows back in through gaps around doors and the window. Part of the cooling capacity is lost this way.

That is why a good window seal matters more than a few extra BTU: a sealing kit for tilt or sliding windows costs little and makes a noticeable difference. Dual-hose units, which draw in outside air to cool the condenser, partly avoid the problem but are rare.

Cooling capacity is stated in BTU/h or kilowatts; 1 kW equals roughly 3,400 BTU. As a rule of thumb, allow 60–100 W of cooling per square metre, depending on insulation, window area and sun exposure.

At 52 to 65 dB, monoblocks are clearly audible – somewhere between a running fridge and a vacuum cleaner in the next room. Models with “Silent” in the name (De'Longhi Pinguino Silent, Comfee Breezy Cool) run noticeably quieter in night mode. Most units evaporate the condensate through the exhaust air; in high humidity you will still need to empty the tank now and then.

Useful extras: a timer and night mode, app control if you want to start the unit before you get home, and a heating function if it should also work in spring and autumn.