The Portable Ventless Air Conditioner Myth Busted

A lot of people talk about getting a portable air conditioner with no hot air vent hose. But are they buying into a myth that needs to be busted here and now?

I think it does.

The first thing everyone needs to know is that all air conditioners produce hot air and that must be exhausted to the outside one way or another. Hence the trailing hose that is there to connect the unit to a window kit or wall vent.

If a free standing cooler doesn't have a hose, it's NOT and air conditioning device at all!

ventless air conditionersWhat is it then?

Swamp Cooler

There is a type of air cooing appliance called an evaporative cooler (swamp cooler) that cools air with a very different process to the way a true AC does it. Let me explain.

An AC cools air using a refrigeration process using a big, energy-hungry compressor motor to perform the main part of the work. It compresses a refrigerant gas to chill it and the air passing over pipes filled with the chilled gas is itself chilled. The process also dehumidifies the air.

The motor produces a lot of heat while it's running. That, plus the heat and the moisture removed from the air needs to be taken out of the building through venting ducts or pipes. That's to stop it actually heating the place, which it will do as it produces more heat than cold!

An evaporative cooler, on the other hand has no large motor or refrigerant gases. It cools air simply by evaporating moisture and forcing the chilled air out using a simple fan. It produces no heat itself and the heat from the air is absorbed by the moisture, resulting in cold air.

Since it doesn't produce any heat, there is nothing to be vented away, so a swamp cooler has no need of a vent hose.

This is the type of cooler that is often advertised as a "portable vent free air conditioner " by hardware stores and websites online. The only misleading part is the naming: it is NOT an air conditioner!

AC vs Evaporative Cooling

For most situations, a regular portable air conditioner is the most effective free standing device for cooling a space. As it dehumidifies as well as cools the air, it is the only way we have to feel cool in places that have high temperatures coupled with high humidity levels.

However, for areas that have high temperatures but very low humidity levels, a swamp cooler is a perfectly good alternative cooling solution. Dry air is not so good for a person's respiratory system, so the humidifying affect of evaporative coolers is actually a welcome by-product of the process in arid climates.

The major advantage of evaporative cooling over AC is the running cost of the device.

An evaporative cooling unit uses typically 1/10 of the electricity that an AC of similar cooling output uses. That represents a huge saving in electricity bills, as many people are already very aware when running whole house AC systems through the summer.

Energy costs are already high and they just keep on going up!

The major disadvantage of evaporative cooling devices is they will not work well in humid climates. Because of the way they cool the air using evaporation of moisture, when they are placed in a humid situation, the air becomes saturated with moisture and cannot absorb any more.

That's why swamp coolers don't seem to work when the humidity is high!

What Device to Buy?

Before you go out to buy a cooling device of one form or another, you need to know beforehand what the average humidity is in your locale. If it's very low, then you can count yourself among the lucky ones who can experience welcome coolness for a low operating cost from a swamp cooler (or misnamed "ventless AC").

However, if the humidity in your area is high, you're out of luck... but not out of options. An AC is really your best choice of cooling solution because it is the only one that will actually work in high humidity!

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