I suspect some other reviews have not allowed the unit to go through its start up process – during which time it blows ambient air. When it click on (after 5 mins or so of warm up) it was blowing ice cold air and venting very hot air – so obviously you need to vent that hot air externally – if you are in an apartment you could vent the hot air via the exhaust fan in the bathroom if you don’t have a sliding or awning window to vent air from. I have just ordered a second unit.