Question: What is the difference between an air conditioner and an evaporator? Is one better for my home? I just need something to cool the front room occasionally in the summer and I hate window units. — George F., Burlington, Vt.

Answer: An evaporative cooler can be a cost-effective alternative to an air conditioner but it's not always the best choice. Also known as swamp coolers, evaporative coolers add humidity to the air in your house. They bring in air from the outside, pass it over water-soaked pads, and blow that humidified air inside.

If you live in a hot, dry climate like the Southwest, a swamp cooler can be a very efficient way to cool the house. In hot, humid climates, not so much, because the air in the house is already humid.

Air conditioners work well in humid climates because they help remove some of that humidity from the air. While they're not dehumidifiers per se, the unit recirculates air in the room. As that air passes over the air conditioner's evaporator coil, the moisture in the air condenses and is drained from the unit, while the air is blown back into the room. That process helps cool the air and reduce mugginess.

Both units need regular maintenance. An evaporative cooler's pads need to be changed every few weeks while in use, and an air conditioner's filter needs to be cleaned or replaced each month in the warm season.

If you hate lugging window units in and out of the window each year, look into buying a portable air conditioner.

These typically cost more than window units — sometimes twice as much for the same BTU level — but can be rolled from room to room as needed and stored out of the way when not needed.

Just remember that the portable unit's ventilation hose must vent outside, meaning the unit needs to stay near a window. And you probably will need to empty the condensation tray regularly, in cheaper units.

A final alternative is natural ventilation. If you get cool nights or steady breezes, open windows in the early morning and late evening, and invest in heavy curtains to cover windows in which the sun shines during the afternoon. Add an electric fan to keep fresh air circulating constantly. In certain climates, this can give you a comfortable home except for the hottest, most humid days of the year.

Home tip

BTUs (British thermal units) are important in buying an air conditioner. Find out the minimum BTU level you need for the space you're trying to cool before purchasing.

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(c) 2014 King Features

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