Yes, single hose portable air conditioners pull air from outside the room they are placed in. These portable units work by drawing in warm air from the room, cooling it through a refrigeration process, and then releasing the cooled air back into the room. To accomplish this, they use a single hose for ventilation.
The single hose serves a dual purpose:
Exhaust air: The hot air generated from the cooling process is vented outside through the hose. This ensures that the heat removed from the indoor air is expelled outdoors, preventing the air conditioner from recycling the same warm air continuously.
Air intake: Since warm air is being pushed out through the exhaust hose, the air conditioner needs to draw in fresh air from somewhere to replace it. This fresh air is typically pulled in from the room's surroundings, which can include air from outside the room.
Because single hose portable air conditioners rely on drawing air from inside the room for cooling, they may have some drawbacks:
Negative air pressure: Since they draw air from the room for cooling, they create a slight negative pressure inside the room, which can cause warm air to be drawn in from adjacent spaces or through leaks in doors and windows.
Inefficient cooling: The warm air that enters the room through leaks or openings can reduce the air conditioner's efficiency since it increases the overall temperature that the unit needs to cool.
Dual hose portable air conditioners are an alternative option that addresses some of the drawbacks of single hose units. They have two hoses—one for intake and one for exhaust—which can improve efficiency and provide better cooling performance by preventing negative air pressure and reducing the need to draw in warm air from the room.