Portable Air Conditioners vs. Evaporative Air Coolers, What’s the Difference?

Portable Air Conditioners vs. Evaporative Air Coolers

Portable Air Conditioners vs. Evaporative Air Coolers, What’s the Difference?

Portable air conditioners are not the same as swamp coolers. As I read through question and answer sites like ask.com or Yahoo! answers, it has become clear to me from both the questions and the answers, that many people don’t understand the difference. Hopefully this article can help clear the waters a bit.

True Air Conditioning

Portable air conditioners are true air conditioners. That means they cool the air by removing heat energy, and blow the cooled air into the room. This is done using a substance called a refrigerant, which is alternately expanded and compressed in coils within the unit. In the evaporator, or expansion coil, refrigerant is expanded from its compressed state. As it expands, the heat it contains now occupies a much larger volume, and the refrigerant becomes very cold. This cools the copper coil, which in turn absorbs heat energy from the air passing over it, and warms the refrigerant inside as it passes through.

As the refrigerant is moved to the condenser, or compression coil, it is compressed by a pump into a high pressure tubing. The heat energy that was absorbed in the evaporator coil is now concentrated into a smaller volume, causing the refrigerant to become very hot. It heats the coil on this side, and the heat energy is released into the exhaust air.
This process is called a heat pump because heat energy is actually ‘pumped’ out of the space being cooled. Heat pumps are common to central, window, portable, and other types of air conditioners, as well as refrigerators.

Evaportaive Air Cooling

On the other hand, evaporative air coolers, also called swamp coolers, are not true air conditioners because they don’t condition the air, meaning they don’t remove heat energy. Instead they humidify the air by blowing it through a wet wick. The process of evaporation cools the air being blown out of the unit, so it is cooler directly in front of it. But no heat is actually removed from the room air, so the room as a whole is not cooled. They do add moisture to the air, and in a humid climate this can make the room ‘clammy’.

Evaporative air coolers are especially useful in dry climates as spot coolers. They look somewhat similar to portable air conditioners, and that is likely one source of confusion. But all portable air conditioners have exhaust ducts, and must have an exhaust port to somewhere outside the room, whereas evaporative coolers do not.


One source of confusion is that some portable ac’s, for example some of the Soleus models offered at portablehomeair.com, are actually called ‘evaporative portable air conditioners’ by the manufacturer. But this term refers to the ability of those models to re-evaporate condensate, which is then blown out with the exhaust air, reducing or eliminating the need to empty condensate from the drain pan. The name is an attempt by the manufacturer to advertise that function.

Another source of confusion is all the advertising about ‘ductless portable air conditioners‘. I have seen some folks equate this term with a swamp cooler, but as I said before, a swamp cooler is not an air conditioner at all. Ductless portable ac’s are actually a type of split system with a twist, because instead of being wall mounted like the usual mini-split, the inside component looks much like a portable ac and contains the expansion coil. They in fact do not have ducts, but instead function much like a tiny central air conditioner. They also have an outside component containing the condenser coil and a fan, where heat is released into the air outside. The two components are connected by the heat pump tubing and electrical wires through a small hole in the wall. Since this connection is present, they are not freely movable like a swamp cooler, as is sometimes implied.


The notion that an air conditioner can work with no connection to the outside is wishful thinking at this point in time. We’d all love such a thing, but the idea ignores the way a true air conditioner functions. This is not to say a swamp cooler has no place, it certainly does. But please do not expect it to cool down an entire room. You will be disappointed if you do.

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