The Phoenix area is once again under an Excessive Heat Advisory with temperatures expected to be over 115 degrees through the weekend. It’s already 110° here this morning and it isn’t even noon yet. Earlier this week I wrote about how my swamp cooler was successfully taming the intense desert heat. It just occurred to me that some of you may not be familiar with evaporative coolers, and some of you who might know something about them may have some misconceptions. Here’s what my cooler looks like:
It’s not much to look at, is it? This particular cooler was purchased brand new about five years ago, yet it differs very little from the early twentieth century design upon which it is based.
Behind the louvers are excelsior pads which are kept wet with water. A blower inside the cabinet draws fresh air through the wet pads, and as the air passes through the pads, the water evaporates, causing the air to be cooled. The heat is literally being removed from the air as it vaporizes the water.
That’s probably technical enough for this description. If you want to learn more about how it works, this Wikipedia entry is a good start.
Swamp cooler? I thought you lived in the desert!
Well, yes. At least right now. And that’s where it works the best. Properly called an evaporative cooler, there are a few possible origins of its colloquial name. Perhaps it is because the extra humidity it adds to the air, especially during monsoon season or in an improperly vented room, can make it feel like a swamp. It could be because the air being pulled through the wet excelsior pads cools just like a breeze blowing through wet swamp vegetation. I’ve even heard it suggested that they are called swamp coolers because algae growing in a neglected or improperly maintained cooler can make it smell like a swamp, but that isn’t a problem I’ve ever had in the 30+ years I’ve lived in the desert and used evaporative coolers.
Why use a swamp cooler?
- Energy Efficiency – It uses 1/4 the electricity of mechanically refrigerated air conditioning.
- Fresh Air – An evaporative cooler is constantly adding fresh air, replacing the air as frequently as once per minute.
- Simplicity – An evaporative cooler is a very simple machine, making it economical to purchase, repair, and maintain.
Why aren’t they more common?
For one thing, they only work well in very dry climates, so you are not likely to find them outside of desert areas. Once the dew point gets into the 50’s (relative humidity over about 30%) their cooling performance is severely impaired. Here in North America you’ll find evaporative coolers in the western and southwestern United States as well as in the northern part of Mexico. They are also used in the southern part of Australia.
Even some people who live desert cities have not seen one, or at least wouldn’t recognize one if they did. And others wouldn’t be caught dead using one. I think that’s mostly due to the stigma carried by evaporative coolers as a cooling means of last resort only for the poor who can’t afford “real” air conditioning. While they certainly are inexpensive to buy and install as well as being economical to operate, I don’t understand why that should make them undesirable. I have actually seen ads for RV and mobile home space rentals that state “No evaporative coolers allowed.” So apparently the humble swamp cooler is shunned even within communities that are already considered “downscale” by much of society. It’s a shame so many people are more concerned with appearances and perceived social status than they are about economy, comfort, and environmental impact.
I had an unexpected but pleasant surprise this past Tuesday when one of my posts was selected to be “Freshly Pressed” — featured on the WordPress.com home page. That was quite an honor, and the exposure drove quite a bit of fresh traffic to the site resulting in some new subscribers, too. I’d like to welcome my new readers and remind all of my readers that comments are always open on all my posts, so feel free to surf the archives and share your thoughts.