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 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 digital displays are the easiest to read and set, though the display shouldn't be so bright as to be disruptive in the dark. Remote controls vary in their functionality, but even basic ones can be extremely convenient to have 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 100 pounds, though most weigh less than that, and you'll need to remove and remount the window venting kits when the seasons change. 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, while better ones will offer more -- up to five years. Some extend coverage for extra years 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. A very few portable ACs include in-home service as part of the warranty, but that's the exception rather than the rule.
Know before you go
Do you have a window? As we've noted elsewhere in this report, you MUST have a window to use a portable air conditioners as they need to be able to vent hot air outside to deliver cool air inside. We saw many low ratings from unhappy buyers who did not realize this, and it tends to bring down the overall rating for these units for something that isn't the AC's fault. Portable air conditioners come 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. Most portable ACs come with five foot exhaust and intake (in the case of dual-hose models) hoses. Makers generally caution that for best performance, the hose length should not be extended.
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 under typical conditions. 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 draw a lot of current. Make sure the outlet is on a circuit that can handle the load and don't add to the strain by connecting too many other electrical devices to the same line. Experts generally advise against using an extension cord, so check your outlet placement before you buy.