I know. It sounds confusing. It might be. However, there are two major ways of cooling air. Mostly, when we say air conditioner, we normally mean a refrigeration unit. That is to say, it generally compresses Freon to perform the air conditioning.
The second form is water evaporating air conditioners, frequently called swamp coolers.
There is one other possible type that, well I don’t even know if anyone sells them, but I guess I should mention it as it is possibly being used.
Nowadays, the refrigeration type is the most common as it works well in most situations. In essence it works by transferring indoor heat outdoors. While it definitely works best in high humidity, much of the energy used by the unit to remove water from the air. Hence, they do work better in low humidity environments.
Swamp coolers, contrary to their name, work best in non swamp conditions. That is to say, they work best when the climate is dry. They work by blowing air over something soaked with water and they evaporate the water. The evaporation does two things. First it cools the air. Second, it increases the humidity in the air, in a humid environment, that is pretty much a bad thing.
On the other hand, in a desert environment, it actually is good. Increasing air from less than 10 percent to 50 percent increases the comfort. So, in places like Death Valley, the swamp cooler would work pretty effectively. When I was in the Marines, I was temporarily assigned to China Lake, California. (Never did see a lake there) It was a very hot, and dry. The barracks I was in used a swamp cooler very effectively. I was very comfortable while in them. If for some reason I had to live in China Lake the rest of my life, I would be very satisfied with swamp cooling.
However, even there, when the air conditioning really counted, they still used refrigeration. However, condensation was nowhere near the problem we have here in Desoto County. My little 8000 BTU unit takes about a quart of water from my 900 sq ft house in less than half a day. That takes a lot of KW hours. On the other hand, it does lower the humidity in my house.
Right now, it is 58% humidity in my house and probably close to 90% outside. To me, that is worth the the money I paid for the window unit as well as the electricity I pay for.
The third type, hardly worth mentioning, simply compresses room air and cools it, generally with outdoor air, then decompresses the air back into the room. I am told, that though it is effective, the air going back into the room frequently contains ice crystals. I have no idea, at all, how efficient it is, but I would guess it is impractical. Otherwise they’d be building them like crazy.
Now. Why in the world am I going through all this explanation. There are a slew of ads these days where they are advertising what they call air conditioners and they aren’t much bigger than a shoe box. Technically, they are air conditioners, swamp coolers. They do cool the air going through them and, they are effective in some situations. However, do not expect them to work as well as my window unit, and certainly not as the central units. In China Lake, they will be effective. In Desoto County, not so much.
As a quick afterthought, I guess I should add that there is one more type of unit, those powered by natural gas. I checked into getting one for my house. The guy said yes, they are far more efficient. However, it would take about 40 years to recover the expense of buying one. They are big and expensive to purchase and install. In the early 1900s they were very common. However, today they are mostly used in situations where large areas need to be cooled. Even so, I really put them in the same category as the refrigeration type, in that they do cool by refrigeration.
I do find them somewhat confusing though, in that they use the heat from a gas flame as the energy source for cooling. It seems very contradictory.
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