Evaporative coolers, also known as swamp coolers, are cooling appliances that cool the air using the natural process of water evaporation. Swamp coolers are economical, eco-friendly, and low-maintenance alternatives to traditional air conditioners. They typically cost less to purchase and their daily operating cost can be up to 80% lower than an air conditioner.
Ready to get rid of your air conditioner? Not so fast. There's a catch. Swamp coolers do their best cooling in hot dry climates where humidity is regularly below 50%. That means if you live in the northwestern and southwestern United States and certain parts of the Midwest, a swamp cooler is for you. If you live in a more humid climate, a swamp cooler will still work for you if you are planning to use it outdoors or semi-outdoors. Great spot cooling applications include: patios, pool areas, warehouses, loading docks, construction sites, kennels, and garages.
For quick reference to the different sections in this article, use the links below:
How They Work
Residential & Commercial Applications
Choosing the Right Size
How Evaporative Coolers Work
Evaporative coolers cool the air by evaporating water. They pull in dry, stale air and move it over a water-moistened cooling pad. Here, cool water evaporates into the air, a process that cools the air internally by as much as 20 degrees. Cooled air is then released and re-circulated back into your environment with the help of a high-power yet efficient fan. Ultimately, this creates a cool gentle breeze that reduces your air temperature.
For optimal cooling, it's important that your swamp cooler have access to a constant supply of fresh air like an open window or door. Swamp coolers won't cool adequately in enclosed spaces. Without a fresh air supply, the humidity in your space will increase and your air will start to feel damp and clammy, not cool and fresh. Most swamp coolers need to be filled with water manually, just like you would fill a humidifier. Other models have direct hose hook-ups to make refilling less of a hassle.
Residential and Commercial Applications
Evaporative air coolers are popular cost-effective cooling solutions in many residential and commercial applications. If temperature and humidity conditions are right, you can use an indoor swamp cooler to cool your living space, bedroom, den, or another warm and stuffy part of your home. Indoor/outdoor swamp coolers are popular for cooling patios, sunrooms, and garages. Outdoor swamp coolers work well for cooling pool areas, backyards, and decks.
Evaporative coolers are also ideal for budget cooling in many commercial and industrial applications in dry, hot climates. Commercial swamp coolers can effectively cool athletic fields, stables, and farms. And they're regularly used at construction sites, manufacturing plants, aircraft hangars, military training facilities, workshops, and more.
Evaporative Cooler Types
Swamp coolers are available in 2 types: portable and window-mount coolers.
Portable swamp coolers are freestanding units that are designed for mobility, and they often feature large caster wheels and carrying handles to make it easier to move them around in your space. These air coolers are great options if you need flexibility and a cooler that goes anywhere you need it to.
Window-mount swamp coolers install permanently through a window and save valuable floor space. Window-mount coolers have the advantage of being able to cool larger areas and having a constant fresh air supply.
Choosing the Right Size
Size is paramount when choosing an evaporative cooler. A cooler that is rated too small for your space won't adequately cool it and may become an energy workhorse. A cooler that's too large for your space may be overkill. The key to choosing the right size swamp cooler is choosing one with the right CFM rating, or cubic feet per minute. This refers to the amount of air that passes through the cooler per minute. As a rule of thumb, the higher a swamp cooler's CFM rating, the faster it cools the air and better coverage in your space.
Calculating the CFM rating you need for your space is simple. Just find the cubic footage of your room or area you want to cool and divide it by 2.
Cubic Footage of Cooling Area = Square Footage x Ceiling Height
Ideal CFM Rating = Cubic Footage of Cooling Area / 2
Let's say the room you want to cool is 144 square feet and you have standard 8-foot ceilings. Here is your calculation:
144 x 8 / 2 = 576 CFMs
For optimal cooling in your room, you need an evaporative cooler that cools air at a rate of 576 CFMs. When deciding among your options, choose a cooler that's slightly larger than your needs to ensure the best performance.
Browse the recommended CFMs below to see the approximate CFMs you'll need for your square footage. For these recommendations, we assume your space has 8-foot ceilings.
- 400 to 1,600 CFMs will cover 100 to 400 square feet
- 1,800 to 3,600 CFMs will cover 450 to 900 square feet
- 3,800 to 6,000 CFMs will cover 950 to 1,500 square feet
- 6,200 to 7,200 CFMs will cover 1,550 to 1,800 square feet
- 7,400 CFMs or more will cover 1,850 square feet and larger
In certain situations, we recommend you choose a swamp cooler with higher CFMs even if your calculated CFM level is lower. In particular, consider:
- Ceiling Height - If your ceilings are higher than the standard 8 feet, choose a swamp cooler with higher CFMs.
- Sunlight - If your space is exposed to direct sunlight throughout the day, go with higher CFMs.
- Number of Occupants - Increase CFMs if more than 2 people will occupy the space.
- Heat-Generating Appliances - Go with more CFMs if you have many heat-generating appliances in the cooling area.
Swamp Cooler Capacity
When sizing a swamp cooler, you can also consider the unit's water capacity. This information is particularly helpful if a CFM rating isn't specified by the manufacturer. Water capacity in gallons gives you a general idea of how large of a space a swamp cooler will cool. Window-mount coolers and some large portable evaporative coolers typically have direct hose hook-ups, so water capacity is endless. If want a portable cooler and you're using water capacity as your guide, use the recommendations below.
- 1 to 3 gallon capacity is ideal for small areas such as small bedrooms, home offices, kitchens, and sitting rooms
- 3 to 7 gallon capacity is ideal for medium areas such as dens, sunrooms, and living rooms
- 7 to 12 gallon capacity is ideal for large areas like large living rooms, large bedrooms, and cooling multiple rooms
- 12 to 16 gallon capacity is ideal for outdoor living areas such as large decks, pool areas, and patios
- 16 gallon+ capacity is ideal for commercial and industrial spaces like sports fields, restaurant decks, farming applications, construction sites, aircraft hangars, and manufacturing plants
Like all home appliances, evaporative coolers include a variety of convenience features that make operating them easy. Consider how important these bells whistles are to you when shopping for a model.
- Multiple Cooling Speeds - Enjoy cool air faster with multiple cooling speeds to choose from.
- Oscillating Louvers - Direct airflow where you need it for the most cooling coverage with automatically oscillating louvers or adjustable louvers you move by hand.
- Digital Controls - Digital controls let you choose settings more precisely and even set a specific cooling temperature.
- Indoor and Outdoor Operation - Indoor/outdoor swamp coolers (and outdoor-only coolers) are built with weatherized cabinets to withstand the elements.
- Fill Design - Smaller swamp coolers have removable water reservoirs you can tote to a sink and back. Other models may feature a pour-in design or hose hookups for direct filling.
- Ice Compartment - Add ice cubes to an ice compartment for an even greater cooling effect.
- Remote Control - A remote allows you to adjust settings from a comfortable distance.
- Timer - Program your cooler to turn on or off at certain times of the day. This can be a great energy-saving feature.
- Air Filtration - Clean the air of large allergen particles like dust and pollen as you cool by choosing a model with added air filtration. Some swamp coolers also include activated carbon filters for odor filtration.
- Ionizer - Ionizers keep the air fresh by releasing negative ions into your space.
- Additional Modes - Some models can work independently as humidifiers, air purifiers, heaters, and fans.
- Casters - Casters make it easy to move portable swamp coolers from room to room for widespread cooling.
Evaporative coolers are fairly simple to maintain. Like humidifiers, they require periodic cleaning to prevent mold and mildew from building up inside the water reservoir. (SmartShield Antimicrobial Protective Spray makes this part easy.) Some manufacturers recommend draining air coolers once per week to help prevent fungus growth. You'll also need to clean or replace the evaporative cooling pads once each season or more frequently. This eliminates mineral buildup from the water and ensures maximum moisture absorption for cooling. Any air filters included on your model will also need to be cleaned and/or replaced periodically.
Before choosing a swamp cooler, ensure that you live in the ideal climate for one. Swamp coolers work best in hot, dry climates like that of the northeastern and southwestern United States. If you live in the north and southeastern parts of the U.S. as well as most of the Midwest, you're probably better off with a central or room air conditioner. Start your search by learning how to choose a room air conditioner.
Still Have Questions?
For more information on our evaporative coolers and other air treatment products that can help improve your indoor air quality, shop our products and visit our Knowledge Center. Not sure what's best for you? We can take the guesswork out of decision-making. Contact our product experts toll-free at 1-800-934-9194. We want to help make your indoor environment healthy and comfortable.
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