How to Buy a Portable Air Conditioner

What the best portable air conditioner has

• Adequate cooling performance. Units with the same cooling capacity can differ widely in how well they actually cool the air in a room.

• The ability to remove moisture from air. A good air conditioner should dehumidify as well as cool, and models that excel at one may not be good at the other.

• Reasonably quiet operation. One of the most common complaints we saw about portable air conditioners was that they are disruptively loud.

• Easy setup. Users tend to say that venting the exhaust hose out the window is the trickiest part of the process.

• Convenient features. Features that users especially like include self-evaporation (which reduces the need to drain the unit), easy drainage, remote controls and casters for wheeling the air conditioner from room to room.

• Good value for money. Consider durability as well as cost, since a cheap model that doesn't last will cost more in the long run.

• A strong warranty. Look not just at the length of the warranty but also at details such as whether it covers labor and shipping costs.

Know before you go

How big a space are you cooling? The cooling capacity of a portable air conditioner is measured in British thermal units (Btu). The chart below, from the retail site Air-n-water.com, offers a rough estimate of the cooling power needed for your room size. Manufacturers may claim that their units can cool a larger space than the chart indicates, but reviews show that these claims are often exaggerated.

How humid is your climate? In a hot and dry climate, an air conditioner will not need to pull much moisture out of the air. Thus, you will not need to drain the unit very often. Many people who live in the dry Southwest say that they use self-evaporating air conditioners and never need to drain them at all. In a humid area, by contrast, it's very important to have a unit that is easy to drain.

The best option is a hose that can be run out a window to drain the water continuously. This means choosing a unit with a condensate pump to move the water upwards (or else raising the whole air conditioner up to window height). Second best is a unit with a large, built-in water reservoir and an automatic shut-off to turn off the air conditioner when the tank is full. Without this feature, you risk having the tank overflow and flood your room.

What kind of windows do you have? Every portable air conditioner must be vented to the outdoors, usually through a window. Check to make sure that the installation kit provided with the unit will fit the type of window you want to use. If your windows are too large for the kit, think about whether you can rig something up to fit. Several owners describe fashioning makeshift systems with some combination of plywood, packing foam and duct tape.

The position of the window is also an issue. The air conditioner must sit close enough to a window for the exhaust hose to reach out. The shorter and straighter the hose is, the more efficiently the air conditioner will work. Check to see how close to a window you can place your air conditioner, and think about whether you will need to raise the unit up off the floor to keep the hose straight.

Does white noise bother you? Portable air conditioners tend to be loud. However, the same unit that sounds unbearably loud to one person may register as no more than a pleasant hum to another. Check the decibel rating of the air conditioner before buying, and if possible, listen to it running and think about whether you can live with that level of noise.

How much weight can you handle? Portable air conditioners are heavy. The models covered in our sources range from around 50 to 85 pounds. Features like casters and carrying handles can make the unit easier to move, but you may still want to avoid choosing a unit that's too heavy for you to lift if you plan to move it from room to room.