When it comes to the hot summer months, having a swamp cooler or evaporative cooler at home can mean the difference between lounging comfortably or feeling like you stepped into a sauna. Those who are in the market to have or buy a swamp cooler or evaporative cooler tend to have a common question: what’s the difference?
Swamp cooler vs. evaporative cooler: what is the difference? The main difference between swamp coolers and evaporative coolers is the size of the unit. The term “swamp cooler” is most often used to describe an entire-house evaporative cooling unit, where the term “evaporative cooler” can describe an evaporative cooler of any size – even portable.
To provide you with everything you need to know about swamp and evaporative coolers, we’ll walk you through the difference between the two, what they can each do and how they work, the pros and cons of each, and how they can be beneficial in urban and backyard farming.
Swamp Coolers vs. Evaporative Coolers
You may have some preconceived notions about swamp coolers and evaporative coolers, as many others do. You probably know that the terms “swamp cooler” and “evaporative cooler” seem to be frequently used interchangeably. That much is true.
But what is the actual difference between swamp coolers and evaporative coolers? Why are the two terms used so interchangeably? It’s actually a breeze to understand.
The Main Difference
When people discuss swamp coolers and evaporative coolers, they’re actually referring to almost the same thing.
While no one is sure where the term “swamp cooler” originated, it’s been dubbed a colloquial expression used to describe a standard evaporative cooler. So, really, swamp coolers are evaporative coolers – they just have one main difference as far as we can ascertain.
Swamp coolers and evaporative coolers only have one difference: the size of the unit.
When people discuss swamp coolers, they’re likely referring to an evaporative cooling unit for an entire house. On the flip side, evaporative coolers can be any size – even small and portable.
Swamp coolers tend to be large and powerful enough to cool down an entire house or a large space, where evaporative coolers are more likely to cool down one room or area at a time.
When people refer to swamp coolers, they are often referring to industrial evaporative coolers, which can cool down spaces like warehouses, automotive shops, and other large spaces.
However, it’s still important to reiterate that the terms “swamp cooler” and “evaporative cooler” are used interchangeably by many people. When looking into buying them or when discussing them, you may need to look into more details to find out just which is being referred to.
Luckily, you’re now knowledgeable enough to know the main difference between the two!
How Swamp Coolers and Evaporative Coolers Work
Swamp coolers work the same as evaporative coolers, as the main difference between the two is what size of evaporative cooler is being referred to.
So, how do swamp coolers and evaporative coolers work?
You might think that swamp coolers and evaporative coolers are the same as air conditioning, but while they share some similarities, swamp coolers and evaporative coolers work differently and have different purposes than air conditioning.
Swamp coolers, evaporative coolers, and air conditioning are all capable of cooling off a room or area, but evaporative coolers only use water and a fan in order to do so, rather than by using refrigerant and a compressor to suck the heat out of the air (like air conditioners do).
Water evaporation, which is a naturally occurring process, cools down things nearby as the water evaporates into the air. Swamp coolers and evaporative coolers take advantage of and harness this process with water and a built-in fan.
A good way to explain the process of water evaporation and why it works: think of how you feel when you get out of a brisk pool on a hot summer day. Even though you felt comfortable inside the water, and even though it’s hot outside, you feel chilly as the water evaporates off your skin.
Swamp coolers and evaporative coolers work to cool homes and areas using that same concept.
Evaporative coolers and swamp coolers are built with an interior cooling pad with a large surface area. As water soaks into the cooling pad, the built-in fan draws the dry and warm air across the cooling pad. When this happens, the water evaporates quickly, resulting in colder air spreading around the room/area.
Swamp Coolers, Evaporative Coolers, and Humidity
Another important thing to note about swamp coolers and evaporative coolers is their relationship with humidity.
While air conditioners can work in any climate, swamp coolers and evaporative coolers are better suited to dry climates; they don’t work well in humid climates.
As you can probably tell from the process of how evaporative coolers and swamp coolers work, a lot of water is involved. After all – both are based on water evaporation! All that water evaporation leads to a lot of humidity in the air.
Simply put, swamp coolers and evaporative coolers add humidity to the air instead of removing it.
Because of this, when it comes to already humid climates, the water in the swamp cooler or evaporative cooler won’t evaporate at a fast enough rate to actually drop the temperature in the room or area.
Additionally, using a swamp cooler or evaporative cooler in an already humid climate will just add more humidity and most likely make the room or area even more uncomfortable and sticky.
Swamp coolers and evaporative coolers of any size are suited to dry climates, and tend to work best in states like:
- Arizona
- Utah
- Nevada
- California
- New Mexico
- Idaho
- Montana
- Wyoming
- Oregon
- Washington
If you think you might live in an area that isn’t on the list but that might still be able to benefit from a swamp cooler or evaporative cooler, you can refer to this page offered by the U.S. Geological Survey.
The USGS offers a map of the entire continental United States with the zones and states in which swamp coolers and evaporative coolers work best.
Size Matters and Makes a Difference
As you’ve read, the main difference between swamp coolers and evaporative coolers is the size of the unit. The size of the unit also affects the size of the area that can be cooled. In short, when it comes to swamp coolers and evaporative coolers, size matters!
So, what are the sizes of swamp coolers and evaporative coolers? What size would you need for a certain room, area, or your whole home?
First, you’ll need an estimate of the size of the area(s) you’re trying to cool. Square feet works best. Once you know that information, you can refer to a simple chart for a baseline of what size swamp cooler or evaporative cooler is best for you.
There’s also some important verbiage to note when it comes to the sizing of swamp coolers and evaporative coolers. The abbreviation CFM stands for cubic feet per minute and refers to the amount of fresh air that is cycled through the room/area per minute.
Swamp Cooler and Evaporative Cooler Size Charts
| Square Footage of the Space/Area | Recommended CFMs |
| 0 – 250 square feet | 200 – 750 CFMs |
| 251 – 500 square feet | 751 – 2,000 CFMs |
| 501 – 1,000 square feet | 2,001 – 4,000 CFMs |
| 1,001 – 2,000 square feet | 4,001 – 7,500 CFMs |
| Over 2,000 square feet | 7,501+ CFMs |
Sylvane.com also recommends adding 20% more CFMs if the space to be cooled has ceilings higher than 8 feet, is exposed to direct sunlight during the day, has a lot of heat-generating appliances present, or has more than two people in occupancy.
There are also different types of swamp coolers and evaporative coolers that come in a variety of different sizes, but some types are generally larger than others:
| Type of Cooler | Use and Size |
| Residential Evaporative Coolers | Used to cool single living spaces.Typically relatively small and portable, with casters to make moving from space to space easier, but can be medium-large sized. |
| Window-Mounted Evaporative Coolers | Mounted in the window of a living space or room for “spot cooling.”Typically several feet wide by several feet tall by several feet deep. Usually mid to large-sized.May sometimes be referred to as “swamp coolers.” |
| Industrial Evaporative Coolers (Swamp Coolers) | For cooling large areas like warehouses, workshops, and auto garages.Typically large-sized and larger than window-mounted evaporative coolers.Commonly referred to as “swamp coolers.” |
| Outdoor Evaporative Coolers | Used for cooling outdoor areas like patios, pavilions, and decks.Typically around the same size as residential evaporative coolers – smaller and portable. |
Pros and Cons of Swamp Coolers and Evaporative Coolers
Like with everything, there are pros and cons to both swamp coolers and evaporative coolers. You may have already noticed a few of each throughout your reading, but we can summarize.
Pros and Cons of Swamp Coolers
| Pros | Cons |
| Capable of cooling off large spaces | Less energy-efficient than other evaporative coolers |
| More cost-effective than other methods of cooling a space | Typically aren’t portable |
| More environmentally friendly than air conditioning | Tend to be very large in size and take up a lot of space |
| Can be capable of cooling very large spaces like warehouses and automobile shops | |
| Humidifies the air |
Pros and Cons of Evaporative Coolers
| Pros | Cons |
| Capable of cooling living spaces, rooms, and smaller areas | Typically only capable of cooling off one room or area at a time |
| Can be portable and small in size | May not be as powerful as “swamp coolers” |
| More environmentally friendly than air conditioning | |
| More cost-effective than other methods of cooling a space | |
| Humidifies the air |
Swamp Coolers and Evaporative Coolers in Urban Farming
Urban farming and backyard farming are no strangers to swamp coolers and evaporative coolers.
In fact, according to the University of Massachusetts Amherst Center for Agriculture, Food, and the Environment, evaporative cooling can help cool the greenhouses used in urban and backyard farming to as much as 10 to 20ºF lower than the outside temperature.
Swamp coolers and evaporative coolers work in this aspect because the evaporating water from the plants, crops, and other wetted surfaces themselves helps cool the areas down.
Evaporative cooling is beneficial to greenhouses and indoor areas in which urban and backyard farming is done in several ways.
In an article on evaporative cooling strategies, Process Cooling notes just how beneficial evaporative cooling can be in indoor and greenhouse farming.
First, modern evaporative coolers and swamp coolers are typically much more energy-efficient than other cooling methods, like air conditioning. In some cases, power usage has been reduced up to 70%!
Not only that, but it’s easier to monitor and tweak desired levels of heat, air, and humidity in the area(s). These benefits can lead to more optimal conditions for plants and crops, and in some instances, even better production.
How to Use Evaporative Cooling in Urban Farming
There are some tips and tricks when it comes to fully utilizing evaporative cooling for urban farming.
It’s important to note that when it comes to evaporative cooling for urban and backyard farming, these tips refer to indoor or greenhouse areas.
In a lot of instances, those who practice urban and backyard farming may construct their own evaporative cooling systems for their greenhouses or indoor growing areas.
In these evaporative cooling systems, cellulose or aspen cooling pads are mounted to either a sidewall or end wall of a greenhouse or other indoor area. Those cooling pads receive a supply of water, typically from a pipe or several pipes that are fashioned above the pads. Any excess water collects in gutters below.
As air is pulled through the cooling pads by fans mounted on the opposite wall(s) from the pads, space is cooled through evaporation.
How can you utilize evaporative cooling to its full potential? It comes down to the size of the equipment and the size of the space being cooled.
Cooling Pad Size
The University of Massachusetts Amherst Center for Agriculture, Food and the Environment notes that the pad size of the swamp cooler or evaporative cooler is important.
The area, or size, of the cooling pads should be sized to accommodate the size of the space and the airflow rate of the evaporative cooler. It’s important to note that there are different types of cooling pads.
Air Flow
The typical airflow rate for cooling a greenhouse or indoor growing area is eight cubic feet per minute per square foot of floor area. You may have to get into a little math here to figure out what airflow rate is best for your space!
Typically, a good airflow rate can be achieved by having the fan of the evaporative cooler at total fan capacity. Remember, fans need to be situated on a wall opposite the cooling pads.
Water Supply
Evaporative cooling doesn’t work without one main element: water.
In urban and backyard farming in greenhouses and indoor spaces, it’s necessary to have enough water to keep the cooling pads wet, but not so much water that the cooling pads are solidly dripping water.
How can you achieve that? There’s a recommended ratio for each type of cooling pad:
| Aspen Pads | ⅓ gallon per minute (gpm) per foot of pad length |
| 4” Thick Cellulose Pads | ½ gallon per minute (gpm) per foot of pad length |
| 6” Thick Cellulose Pads | ¾ gallon per minute (gpm) per foot of pad length |
How to Use Swamp Coolers or Evaporative Coolers in Urban Farming
If your urban or backyard farming setup includes a small freestanding greenhouse or relatively small indoor space, you can also use individual swamp cooler and evaporative cooler units, as opposed to creating an evaporative cooling system.
This method is simple: swamp coolers and evaporative coolers for small freestanding greenhouses are typically mounted outside the greenhouse and then blow the cooled air through the opening(s) in the sidewall.
The greenhouse must have a type of vent, shutter or door in order to expel the hot air that’s being pushed out by evaporative cooling.
For small indoor spaces, residential or window-mounted swamp coolers and evaporative coolers can be used.
Final Thoughts
Swamp coolers and evaporative coolers are terms for evaporative cooling units that are used interchangeably, but they have one main difference: the size of the unit.
When people mention swamp coolers, they’re most often referring to very large units capable of cooling off equally large spaces, like industrial evaporative coolers (swamp coolers).
On the flip side, evaporative coolers can be just about any size, even small and portable!
Swamp coolers and evaporative coolers can be the difference between a comfortable, cool space and a warm, dry space, and they can also make a world of difference in urban and backyard farming.
If a swamp cooler or evaporative cooler could benefit you – whether it be in your home, your farming, or any other area, make sure you always get specifics on the size, capabilities, and unit!