You MUST have a window to use a portable air conditioner
The statement above is the greatest misconception we saw regarding portable air conditioners and it results in a lot of 1-star ratings: people don't realize that, even though a portable air conditioner is not a window air conditioner, you MUST have a window to use a portable air conditioner (although, a sliding door or any other way of venting the exhaust to the outside will do as well). We wanted to make that clear early on, so that, if you don't have the option of venting your portable air conditioner to the outside, you can head on over to our report on fans instead, to find the one that will keep you the coolest.
Now that we have that out of the way….
When considering how to cool a home, there are two main options: central air conditioners (which cool the whole house from a central location) and smaller window or through-the-wall air conditioners that cool down individual rooms. We cover both of those types of air conditioners in their own reports, but there's also a third alternative -- a portable air conditioner. These are similar in scope and cooling capacity to a window air conditioner, but their more modest venting requirements make them easier to install -- especially in rooms where installing a window unit is either undesirable or impossible, such as apartment units where they may be prohibited.
The best portable air conditioners can be set up quickly by just one person and can be moved around to cool a different room as needed, although they're still heavy in spite of having wheels. A portable air conditioner doesn't commandeer a large section of the window (like a window air conditioner does), but a portable AC still needs access to outside air. Each portable unit comes with a window kit, which mounts one or two hoses to a small panel that's installed in a window. Some experts prefer the dual-hose style because it provides slightly better performance. TheSweethome.com says that, while that's true in theory, in practice the difference is actually very slight. In our research, we found that single-hose models often rate as well or better than many dual-hose portable air conditioners, and typically cost less.
All air conditioners, including portable air conditioners, pull excess moisture from the air. This is stored in a water tank that must be periodically emptied (machines will shut down when the tank is full) or drained continually through a hose running outside. Portable air conditioners with a self-evaporative system minimize the need for emptying, though under more humid conditions, the water tank may still need to be emptied occasionally, and more frequently if the humidity is exceptionally high. Some portable air conditioners have dehumidifying functions that pull excess moisture from the air without cooling it. If you are primarily interested in that, we cover dedicated dehumidifiers in their own report.
Why most portable air conditioners get mediocre reviews
In doing the research for this report, we quickly found that expert reviews of portable air conditioners offer only half-hearted recommendations, and user reviews aren't much rosier. Here's the problem:
Like window air conditioners and central air conditioners, the cooling capacity of a portable air conditioner is measured in British Thermal Units, or BTUs. However, notes Liam McCabe at TheSweethome.com, portable air conditioners aren't held to the same rating standards as window units or central air systems, so there's often a disconnect between their claimed BTU rating and the size of room a portable air conditioner can satisfactorily cool. McCabe notes that even different models with the same BTU rating will vary in their actual cooling capacity.
That means that the disparity between the BTU ratings of window and portable air conditioners renders traditional sizing guidelines somewhat moot. Instead, where a 6,000 BTU window air conditioner might be great for a small bedroom, testing shows that you may need to turn to a 10,000 BTU or better portable model to get the same degree of cooling.
These performance shortfalls aren't a result of poor manufacturing, but a byproduct of having a unit that's designed to vent hot air to the outside while sitting entirely in the room it is trying to cool (instead of being half inside and half outside). Still, as most experts and users say, if a portable air conditioner is your only practical option, it's a lot better than having no air conditioner at all on a hot summer day.
Finding the best portable air conditioners
To find the best choices among portable air conditioners, editors read through available, credible expert reviews from sources such as ConsumerReports.org and TheSweethome.com. We then weighed feedback from users as posted at sites such as Amazon.com, HomeDepot.com, Walmart.com and others. We considered performance, how easy the portable air conditioner was to set up and use, and how well it held up over the long haul, including the warranty and customer service reputation of the manufacturer. The result is our picks for a portable air conditioner for any size room.