Unlike single-hose units, dual-hose portable AC (PAC) models feature two separate exhaust hoses. One hose draws air in from the outside while the second hose expels warm air and moisture back outside. This helps prevent cool air from being exhausted out of the room—something that can occur with single-hose PACs and can ultimately decrease a unit's cooling efficiency. The models listed below all are all dual-hose configurations and offer other user-friendly features like self-evaporating technology, digital controls, and adjustable thermostats.
Because of their unique exhaust configurations, dual-hose portable air conditioners are said to cool faster and more efficiently than their single-hose counterparts. In fact, in its July 2009 issue, Consumer Reports recommends purchasing a dual-hose portable air conditioner over a single-hose model. Keep in mind, however, that extensive research proving the benefits of one exhaust system over another has yet to be conducted. One more tip – note that dual-hose PACs can be modified in a pinch to function as single-hose units.