Portable Swamp Coolers That Lower Temps (and Energy Costs)

If you live in a dry climate — especially in the West and Southwest — air conditioning isn't your only option for keeping a room cool. A portable evaporative cooler (aka "swamp" cooler) does basically the same job as a window or portable AC unit, but at a fraction of the cost. With summer upon us, we took a look at what pros recommend and what shoppers are buying, plus tips for how to get the most out of a fancy new swamp cooler.

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Let's put it this way: Do not buy a portable swamp cooler if you live in or near an actual swamp — or in any climate where average humidity levels are at least 60%. That means pretty much anywhere east of the Rocky Mountains, with some exceptions. Why? Evaporative coolers work by forcing air through a wet pad or filter, causing some of the water to evaporate, thus lowering the ambient temperature. High humidity levels inhibit that evaporation process.

Related: The Best Portable Fans Under $100 for Every Room

A window air conditioner has one big advantage over a portable swamp cooler: the ability to control the temperature precisely. Want the room to be a chilly 68 degrees? No problem with AC; just set the thermostat and forget it. There's no thermostat to control the temperature on a swamp cooler; only an adjustable fan. On the other hand, without an energy-hungry motor and refrigeration system to run, an evaporative cooler is quieter and cheaper to operate. A portable swamp cooler can lower the temperature by as much as 20 degrees, but that depends on how powerful the unit is and how hot and humid the weather is. A small tabletop or cheap floor unit is going to cool the room by only about 5 degrees.

Price: $23 from Amazon
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Like a desktop fan, a cheap, small evaporative cooler is not powerful enough to do much more than circulate the air in a small, enclosed space like a cubicle or bedside. This particular model has two speeds — not especially powerful, but sufficient to keep you cool at your desk, owners say. It features a diffuser for essential oils and LED lighting that changes colors (if you're into that sort of thing). It's also got a rechargeable battery, although buyers caution that the water reservoir is easy to spill, limiting the unit's portability.

Price: $29 from Walmart
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This pint-size evaporative cooler has a washable filter and an auto-shutoff function, two nice-to-have features that other cheap coolers lack. Satisfied owners say this two-speed unit works well on a nightstand or desktop but caution that it won't cool larger spaces effectively. It's not rechargeable, either, but it does have a 6-foot cord and a night light. It's available in white or black.

Price: $40 from Walmart
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If As Seen On TV products are like catnip for you, then this is the desktop cooler for you. It costs a few bucks more than similarly sized evaporative coolers — and just like those other models, this one isn't designed for spaces larger than a cubicle or bedside. Unlike rival models, the Arctic Air Ultra has a three-speed fan. Some buyers complain that it is too noisy, but nearly as many say it's not an issue.

Price: $128 from Walmart
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If you want to cool an entire room, you'll need to step up in size and price in order to buy a swamp cooler with sufficient power. This Honeywell three-speed evaporative cooler is designed for rooms of up to 100 square feet, with casters for easy portability, plus a remote control and auto-off timer. Most owners seem satisfied, although some say the water-level meter is tough to read and a vocal minority complain of leaks.

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Price: $178 from Walmart
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This three-speed swamp cooler, designed for rooms up to 250 square feet, is definitely the most eye-catching model in this roundup. Editors at Top Ten Reviews have named it their top pick, although they do wish the 1.7-gallon reservoir were a little larger. Some buyers recommend adding ice to the tank to give the fan a little extra cooling oomph. Like all portable evaporative coolers, this one loses its effectiveness in humid conditions.

Price: $170 from Home Depot
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Both Best Reviews and Top Ten Reviews — two of the relatively few reliable sources that conduct hands-on tests of portable swamp coolers — give this Hessaire model the thumbs-up. It can cool rooms of up to 500 square feet, far more space than similarly priced models (like the Luma Comfort evaporative cooler), and the company makes even more powerful models that can cool up to 3,000 square feet. Another plus: This cooler has an external valve so you can hook it up to a water source (meaning you don't have to refill it by hand, although you can; it's got a 5-gallon reservoir). And it can be used indoors or out — say, near some lawn chairs or the grill on the patio.

Price: $459 from Home Depot
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A big space like a garage, studio, or patio calls for a heavy-duty portable swamp cooler like this one, which can handle up to 850 square feet. The three-speed unit has a 15.9-gallon tank — enough for about eight or nine hours of runtime, owners say — plus a port for an external water source. The primary drawback with this unit is that it is, well, big. And relatively noisy: Honeywell rates it at 65 decibels at full blast, which is louder than some window air conditioners.

Here are some tips for buying and maintaining a portable evaporative cooler:

- Capacity: As in, how much water does that swamp cooler's tank hold? The larger the tank, the longer it can run, but more water means more weight to push from room to room.
- Cubic Feet: A swamp cooler's power is measured in cubic feet per minute. Follow a 4:1 ratio of CFM to square feet of space. For example, if you want to cool a 250-square-foot bedroom, you'll want a swamp cooler rated at 1,000 CFM minimum.
- Circulation: Even though they have built-in fans, swamp coolers work best when there's a steady flow of air in and out of the house. This is more important for larger portable units than for tabletop coolers.
- Connectivity: Sooner or later, your swamp cooler is going to run dry and you'll need to refill the tank. But some room-sized models have hoses that can be connected to an external water source.
- Cleaning: Swamp coolers need to be cleaned periodically to remove calcium buildup and to prevent mold growth, and filters must be replaced on a regular basis. Fiber-pad filters are most common and fairly cheap, but rigid-media pads are more durable (if pricier).