Consumer Reports: Air conditioners

Portable air conditioners sound like an easy solution for cooling a room that can't accommodate a window air conditioner, but many are returned by unhappy customers. So Consumer Reports tested 8 from Honeywell, Haier, Frigidaire and Sunpentown, ranging in price from $250 to more than $500.

Consumer Reports used a special chamber to test their cooling power. The temperature outside is kept at 90 degrees, the humidity at 70 percent. Inside, each air conditioner is set to 75 degrees. Strings of thermocouples record temperatures throughout the room.

The results were disappointing. None of the units, not even the biggest ones, could get the test chamber below 80 degrees even after an hour and forty minutes.

That was true even of the most expensive unit tested - the $550 Honeywell MM14CCS, which promises it "cools up to 550 square feet." It struggled to cool the test chamber, which is half that size.

Consumer Reports' tests show window air conditioners are much more effective and they tend to cost less. Consumer Reports found several to recommend.

Top-rated for larger rooms (350 to 650 square feet), the $350 LG LW1214ER.

For medium-sized rooms (250 to 400 square feet), the LG LW8014ER for $240.

And for smaller rooms (about 100 to 300 square feet), the $210 GE AEM05LS is a Consumer Reports Best Buy.

Consumer Reports says be sure to pick the right size air conditioner for your space. If the unit is too small, your room won't get cool enough. But an air conditioner that's too big may make it feel cold and clammy.

A 5,000 to 6,000 BTU air conditioner will cool a small space - about 100 to 300 square feet. For rooms 250 to 400 square feet, choose a unit with about 7,000 to 8,000 BTUs. And for larger areas - about 350 to 650 square feet - you'll want a unit with about 9,800 to 12,500 BTUs.