There seems to be a lot of confusion out there about portable air conditioners and swamp coolers.
They are not interchangeable. An air conditioner cools, or conditions, the air by removing heat energy. The result is that the air has less heat energy, so the entire space is cooled. They do this using a heat pump. Heat pumps can be found in all types of air conditioners, as well as refrigerators.
In a heat pump, a liquid with special properties, called a refrigerant, is expanded slowly through a valve into a low pressure tubing called the evaporator, or expansion coil. As it expands, the heat energy in the refrigerant becomes much less concentrated, and it becomes very cold.
This is the cooling side, where heat from the air passing over it now is readily absorbed by the cold copper tubing, which then warms the refrigerant as well.
When the refrigerant circulates to the compression coil, or condenser, it is pumped into a small, high pressure tubing. All the heat energy being brought from the evaporator coil is now squeezed into a smaller volume, and the refrigerant becomes extremely hot.
This is the hot side. The coil heats up and readily releases the excess heat to the air blowing over this side. In a portable air conditioner, this air is blown out via the exhaust duct.
Portable air conditioners use the heat pump system, and are designed as room air conditioners. In some, the circulation of refrigerant can be reversed, which results in the heater function found in those models.
In contrast, evaporative air coolers, or swamp coolers, do not remove heat energy from the air, and therefore are not air conditioners. The term ‘super-fan’ could be applied here. Swamp coolers cool air by blowing it over a wet wick. Moisture in the wick evaporates, cooling the air blown by the fan.
So it feels cool in front of the unit, but nowhere else. No heat is removed from the air, but moisture is added, so the room itself contains the same amount of heat energy and is not cooled. Swamp coolers are not able to warm the air.
The added moisture from a swamp cooler can make the room uncomfortably humid, especially where ambient humidity is already high. They are best suited for dry climates, used as spot coolers. Swamp coolers look a bit like portable ac units, but do not have exhaust ducts.
Advertisement photos of portable ac’s tend to leave out the exhaust ducts, probably adding to the confusion.
Adding to the confusion is the term ‘evaporative portable air conditioner’, used by some manufacturers. The title advertises a function these units have, that being the evaporation of the water which condensates during the heat pump cycle. The evaporated condensate is then removed with the exhaust air.
The purpose is to remove the necessity of emptying the drain pan that was such a hassle in older models without this function.
Yet another confusing term is the ‘ductless portable air conditioner’ one might see advertised. This is actually a name given to a type of mini split ac that uses a mobile inside unit to house the expansion coil, instead of the usual wall mounted console.
It is true they don’t have ducts, but they still must be connected to the outside via a small hole in the wall, so the heat pump tubing and wires can connect the mobile portion to the outside fan, where the condenser is located.
I hope this article has identified the source of some of the confusion about portable air conditioners and swamp coolers, and helped the reader understand the difference. While both are useful, their uses are quite different.
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