What the best portable air conditioner has

  • Energy efficiency. The energy efficiency rating (EER) is a measurement of how much energy it takes to run an air conditioner in relation to its cooling capacity. A higher number indicates a more efficient unit, which can save money on the monthly electric bill. However, portable air conditioners aren't efficient enough to be Energy Star Qualified.
  • Low fan noise. A loud compressor is one of the most common air conditioner complaints -- owners want to be able to stay cool while comfortably watching TV or sleeping. Portable air conditioners tend to be louder than window units of the same capacity, but the best ones keep noise levels below that of a typical conversation -- 60 to 65 dB
  • User-friendly controls. Portable air conditioners with a digital display are the easiest to read and set, though the display shouldn't be glaring enough to be disruptive in the dark. Remote controls vary in their functionality, but even basic ones can be extremely convenient in bedrooms and large living rooms.
  • Dehumidifier. While all portable air conditioners remove a certain amount of moisture from the air, the best feature is a separate dehumidifying function. This reduces the humidity in your room without adding an icy blast, a handy setting for muggy days that aren't hot enough for air conditioning.
  • Easy to move. To be fair, portable air conditioners are really only "portable" in relation to window or through-the-wall air conditioners that are permanently or semi-permanently mounted. Most are heavy, as much as 80 pounds, and you'll need to remove and remount the window venting kits. Still, castors can make moving a portable AC into another room a lot easier, as can conveniently located handles. However, you need to keep that weight in mind if you are intending to buy a portable air conditioner for use on multiple floors as hauling one up and down the stairs might be quite a chore. A portable air conditioner with a more compact design will be lighter and will save space.
  • Warranty. Portable air conditioners are generally covered by a one year warranty, though some cheaper models might have less coverage. Some extend coverage for extra years (up to five) for the sealed cooling units, but these generally cover parts and not labor, plus you will likely bear the cost of shipping or otherwise transporting the unit to an authorized service center.

Know before you go

How big a portable air conditioner do you need? Select the size of your portable air conditioner based on the square footage and setting of your space. The ideal size has enough power to effectively cool your room while running long enough to remove as much moisture from the air as possible. Because of the challenges all portable AC units have in cooling a room compared to window models, expect cooling to be notably lower than a like-sized window air conditioner -- delivering only 60 percent of the cooling according to testing by ConsumerReports.org. As a guideline, expect a 10,000 BTU portable AC to be adequate for rooms up to 350 square feet, a 12,000 BTU portable air conditioner to be suitable for spaces up to 425 feet or so, and 14,000 BTU models to be right-sized for rooms of around 500 square feet. Keep in mind that because standards for portable air conditioners are looser than those for other types of air conditioners, like-sized models from different makers may deliver a little more or less cooling than that. Rooms bigger than 500 square feet will present a challenge for even the largest consumer portable ACs. Portable air conditioners rated lower than 10,000 BTU are available, but are only suitable for very small rooms.

A window is still required. Air conditioners need to be able to vent hot air outside to deliver cool air inside, and a portable unit is no different. Each comes with a window kit, which uses a few inches of window space for a vent hose or hoses. Installing these kits is usually straightforward, but some instructions require you to screw the mounts into the sill and sash, or to use duct tape to hold it in place and seal against leaks. Complaints about difficult-to-install window vent kits and unclear assembly instructions sometimes crop up in user reviews of many otherwise well-liked portable air conditioners.

Will you need to empty the water tank? Air conditioners pull extra moisture out of the air -- reducing your room's humidity and making it more comfortable. The best units use a self-evaporative system to automatically disperse this moisture out of the vent hose. For units without this system, or in areas or on days that are excessively humid, users have to manually drain the water tank or install a drain hose.

Filtering the air. Most portable air conditioners include one or two built-in air filters. For maximum filtration, look for a unit that has a washable pre-filter and an additional carbon filter, which can remove finer particles such as mold, pollen and dust. Some dehumidifiers have ionization features to better trap particles.

Check your outlets. Most portable air conditioners use standard 115-volt AC, but they can pull a lot of power; make sure your outlets can manage the extra load. Experts generally advise against using an extension cord.

Elsewhere in this report:

Best Portable Air Conditioners | Best Large Portable Air Conditioners -- 10,000 BTU and above | Our Sources

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