How to choose a portable air conditioner

Jun 10, 2011 at 2:01 p.m. ET

The temperature is on the rise as we head into summer. If your home or office is a little too hot, consider purchasing a freestanding portable air conditioner to keep cool. Portable air conditioning units are convenient because you can get cool air exactly where you need it and roll the unit from room to room. To beat the heat, follow these tips to select the right air conditioner for you.

Window AC

For those who don't have central air, a portable air conditioner is a must during the summertime. If your window space is limited or window air conditioners are prohibited in your building, a freestanding portable air conditioning unit is the answer. Even for those who have a central air conditioning system, you can use a portable unit as a supplement.

1Know your BTUs

BTU stands for British Thermal Unit. It's simply the amount of heat necessary to increase the temperature of one pound of water by one degree Fahrenheit. When it comes to air conditioners, the higher the BTU, the quicker your room will be cooled down. If the BTU rating is too low for the amount of square footage you are trying to cool, the air conditioner will not be able to cool the room adequately. Multiply the width times the length of the room you are trying to cool to determine its square footage. You will need a portable air conditioner with about 30 BTUs per square foot. To save money, don't splurge on an air conditioner with a much higher BTU rating than you need.

2Air conditioner size

The air conditioner's BTU rating isn't the only thing you should consider -- the unit's size and weight are important as well. Portable air conditioners are generally between 24 and 36 inches tall, and vary in shape, size and weight. If you intend to move your AC unit from room to room (or bring it up stairs), the weight certainly will be a factor in your buying decision.

3Bells and whistles

All portable air conditioners are not created equal. Depending on how much you want to spend, you can find units with remote controls, programmable timers and built-in air filters. If you are on a budget, you don't need these extras. Most air conditioners come with dehumidifiers or water reservoirs, as well as exhaust hoses and other venting accessories.

4Before you buy

Keep in mind that portable air conditioners (as well as wall units) can be noisy. See if you can test drive the unit at your home improvement store to see if you can handle its noise level. As your portable air conditioner operates, water will accumulate and go into its drain tank. With most types of portable air conditioners, this water cools the coils inside and is evaporated (or discharged through the exhaust). Unfortunately, with some units, you need to empty the tank manually a couple times of day. Find out as much as you can about the portable air conditioner you want to buy by reading online reviews and customer testimonials. Ask about the manufacturer (and store) warranty, as well as the return policy before making your purchase.

More about air conditioners

Energy-efficient air conditioners
Summertime air-conditioning: Is it a health risk?
Beat the heat with a portable air conditioner