Swamp Cooler Features
Swamp coolers, also know as "air coolers" or "desert coolers," are a kind of evaporative cooler -- simple devices that combine air and water to provide lots of cooling in hot, dry conditions. They may come with any of a number of features that make them more portable -- great for outdoor cooling, more efficient, easier and safer to use.
Portability
Portable swamp coolers are mounted on casters so they can be wheeled from place to place. Heavier units will have wider casters. The wider the caster the easier it will be to move the unit over uneven ground, such as dirt or grass. Look for casters with locking wheels. You might want to use a separate wheeled frame or dolly to move smaller units across uneven ground.
Tanks generally hold enough water to last for a few hours of mild weather. Keep in mind that hotter, drier weather will use more water per hour. Be prepared to refill the tank as necessary. You'll need to consider having an extra supply of water unless a water supply is available. Separate, portable tanks of up to 50 gallons / 190 litres and more are easily available and come with wheeled frames for portability and water lines that you can hook up to your evaporative cooler.
Filters
There are a variety of air filters available to fit most swamp coolers. Carbon filters help eliminate odors. HEPA filters help filter out particles from the air such as dust, pollen, and pet dander (these can be especially helpful for asthma and allergy sufferers). Filters can also extend the life of the pads by reducing the amount of particles that can clog or damage them. Look for sizes that will fit in your unit.
Inspect your unit's filters from time to time. Clean or replace them when they start to get clogged since clogged filters can lower the cooling capacity of your unit.
Speeds
Multiple speed can help you fine tune your cooling and energy use. Low speeds are great for days with milder weather or at night. Low speeds use less electricity and water than high speeds, sometimes saving over 50%. Low speeds are also quieter -- better for sleeping and other activities that may require especially quiet environments.
Use high speeds during the hottest hours of the day or when you need to quickly lower the temperature, such as when the unit has been off for several hours.
Fan Only Option
This allows you turn off the evaporative part of the cooler and just use the fan. This can be great to provide a cooling breeze when the weather is too humid for evaporative cooling. The fan by itself can cool an area by 4 - 8°F / 2 - 4.5°C.
Air Flow - Direction
Being able to adjust the direction of the air flow can help you place the cool air exactly where you need it. If people tend to gather around a certain part of the area you are cooling, perhaps a table or seating area, adjustable louvres can help you direct the main flow of cool air toward that are without moving the cooler. Ducting adapters can be installed onto some units for the same purpose.
Some swamp coolers have an oscillating feature, which means they swivel back and forth to cool a larger area. This changes the direction of the air flow. Even though the amount of air flow doesn't change, it moves, intermittently covering more area than if it were still.
Pre-cool
This setting lets the water run before the fan turns on. If the fan starts at the same time as the water pump, the fan will start blowing hot air before the pads have a chance to fill with water. But with this setting, the pads fill with water first. Then when the fan starts, the air from the unit will immediately be cool.
Thermostat / Timer
A thermostat control can turn the cooler on when the area you want to cool reaches a certain temperature. It can also be set to turn off when the area cools down to a certain temperature. Similar to this is a timer control which turns the unit on and off automatically at certain times rather than at certain temperatures. Both the thermostat and timer can save energy by limiting your cooler's use to when you need it most.
Water Level Sensor
This senses when the water level is low and alerts you with a sound or light. This is especially helpful if you need to refill the tank manually.
Water Purge or Flush
An automatic "water purge" or "flush" control works together with a drain valve to periodically remove the recirculating water from the system and replace it with fresh water. This can prolong the life of your swamp cooler and help keep it clean.
Cabinet Color Options
Swamp coolers are large -- 3 feet / 1 meter vertically and horizontally is not unusual. After all, they contain the workings to move a lot of air and hold many gallons of water. A simple thing like color options can help it blend in with its environment or emphasize its technical and functional appearance.
Noise
Most swamp coolers run fairly quietly. Their pumps and motors aren't very large and they don't use a lot of electricity. But some are built to run more quietly than others. And if you need yours to be especially quiet -- if you'll be running it when people are sleeping, for example -- the noise level may be important to you.
Some manufacturers use a decibel rating (dB) to give you an idea of the amount of noise you can expect from their cooler. But there are a lot of variables involved with how a cooler makes noise.
| Bottom threshold of human hearing | 10dB |
| Recording studio | 20dB |
| Quiet living room | 30dB |
| Quiet office or library, refrigerator | 40dB |
| Quiet conversation | 50dB |
| Average office noise, clothes dryer | 60dB |
| Average conversation, dishwasher | 70dB |
| Average factory | 80dB |
| Typical home stereo volume | 90dB |
| Heavy truck | 100dB |
The noise from a cooler can be made by many things: the motor spinning, the motor's own cooling fan inside the enclosure, the fan blades moving, the pump operating, the water trickling through the unit. Running a cooler on a low setting or fan only will be quieter than the same fan running on high with evaporation.
Even the way it's installed can make it louder or quieter, which is something a manufacturer cannot predict. A unit installed on packed earth or solid rock may make less noise than a unit installed on a raised metal platform.
Consider the quality of the cooler's sound as well as its volume. Different frequencies produce different tones, even at the same decibel level. A low rumbling sound may not be as noticeable as a high whistling sound.
So just use dB ratings to get a general idea of the fan's noise level.
Here's a chart of decibel ratings and the typical sound to which they compare.
Safety Ratings, Safety Features and Installation
Safety Ratings and Installation
Know where you plan to use a swamp cooler and how you plan to set it up before you make your purchase. Swamp coolers and other outdoor cooling devices are rated for safety depending on the conditions of the location where they will be used. With a general idea of its set up, you'll know whether to get a swamp cooler rated for a dry, damp or wet location.
Will it be set up inside a partially enclosed area, such as a tent or shed? Will it be set up on a hard, dry surface, a table or the bare earth? Will it be set up permanently or moved indoors out of the damp night air when not in use? Evaporative coolers are rated for one of three kinds of environments and answering these kinds of questions helps you see which kind of environment you have.
- Many electrical appliances are rated for safety by independent testing agencies such as Underwriters' Laboratory (UL). There are several of these agencies which you can learn more about by going to safetylink.org. They rate electrical appliances for use in 3 kinds of locations:
- DRY -- for indoor use and dry locations ONLY. If you set it up outdoors, protect it from any dampness or wetness. Bring it indoors at night to protect it from the damp night air. Never use a DRY rated cooler in damp or wet locations. It simply doesn't have the right safety features.
- DAMP -- safe for protected outdoor use, for example, open walls with a solid ceiling, in a greenhouse or tent; not good for direct contact with water such as rain or puddles, but outdoor humidity is fine. Can be set on bare earth as long as it doesn't rest in any puddles. Damp rated coolers don't have the safety features to be used safely in wet locations, but they can also be used indoors and in dry outdoor locations.
- WET -- can get totally wet -- rained on or sitting in a puddle is fine; can be cleaned by hosing off. SAFE to use indoors or outdoors. Can be safely used in all 3 kinds of locations.
Look for the testing agency's seal on the box of a new swamp cooler or stamped or labeled somewhere on the cooler, itself. If you are shopping in a catalog or on a website, look for a statement like, "UL damp rated" or "UL rated for wet locations." If the product description says simply "UL Listed" or "ETL Listed," it is safe for dry locations and indoor use. If you can't find a rating for a particular evaporative cooler, contact the retailer or manufacturer before you make your purchase to be sure it will work safely where you need it.
Safety Features
Portable swamp coolers that can be used safely outdoors always include a three-pronged ground or "earth" prong as well as a GFCI plug. These are critical features for any outdoor rated appliance. They ensure that if there is any surge of electricity the appliance will shut off automatically before any major damage can be caused to person or property. Always perform the simple safety test on your GFCI plug before using it outdoors.
Motors and pumps typically include shut-off switches. These switches automatically shut off specific parts of the swamp cooler when there is a condition that could cause overheating of that part. Too much water around the motor could cause it to shut off. Not enough around the pump could cause it to shut off.
Installation and Safety
Much of what makes a swamp cooler, or any electrical appliance, safe to use outdoors is how it is installed and used. You can buy the best-made wet-rated swamp cooler, but if you set it up carelessly it might be unsafe. Read our page on electrical safety outdoors for tips on safely installing and setting up all kinds of outdoor cooling devices.
Basic Installation
Installation involves connecting your swamp cooler to an electricity and water source, and providing a drain for the waste water. This can be tricky if you're setting it up for outdoor cooling. It's often hard to find all of these resources in the location where you want to use your cooler. Because of this they are especially helpful at cooling partly enclosed areas near the outside of buildings that have these resources. Using a generator for a power supply and adding a portable water tank can make them useful almost anywhere.
Have your swamp cooler in position and level before connecting it to water and electricity. You'll need to connect the water supply or fill the water tank before you connect the electricity. This gives you a chance to make sure any water connections are leak-proof and any spills are dried up before connecting the electricity. Make sure all of your connections to electricity are waterproof and use grounding / earth plugs with GFCI protection.
Make sure the area you are cooling has plenty of fresh air available -- at least 2 square feet for every 100 square feet or 0.186 square meters for every 9.3 square meters you want to cool. You may need to open a window or door of a shed or trailer, or pull back the flap of a tent.
The unit will need to run for a few minutes before you feel any cooling. These minutes allow time for the pads to become filled with water that creates the cooling evaporation. When you turn off the unit, you'll need to run the fan for up to 15 minutes with the pump off. This allows the pads to dry out.
