Portable Air Conditioner No Vent Required?

What do you do when you live in a place that has no air conditioning and you can't afford to have it installed?

One option is to buy what is often labeled as a compact, portable air conditioner no vent required model if access to windows is limited or you have the wrong kind of openings for a fixing kit to work.

The only problem with getting excited about this amazing solution to your home's cooling needs is you are chasing a mythical beast.

It does not exist!

Sure you've seen plenty of advertisements and promotions offering a "ventless portable air conditioner" or some other closely related description. And you'd be forgiven for believing them to be cooling units that don't have an exhaust hose that needs to be hooked up to a nearby window via a fixing kit.

The reality is the store advertising the product is either misleading you to get you through the door, or they're actually promoting a different kind of cooling device.

When an AC is Not an AC

There is a type of cooler is not actually an AC, but is more correctly known as an "evaporative cooler" which cools by the evaporation of moisture instead of the refrigeration process employed by an AC. It sounds great on paper and a big selling point is the very low energy consumption when compared to AC.

However, evaporative coolers have some limitations on use depending on the local climate where you live.

If you have high levels of humidity, this kind of cooler will disappoint you because it won't produce much cool air when there is a lot of moisture in the air. As the humidity level rises (greater than 50%) the effective cooling capability of a swamp cooler decreases.

So if the kind of climate you live in is predominantly hot and humid, we're back to the only viable cooling solution available to you right now.

That solution for a humid climate is an AC unit of some description. NOT a swamp cooler.

Portable AC units have their advantages over larger systems. And this is what I want to talk about in this site.

Why the Vent is Needed

Let's take a look at just why an AC needs to have a vent that extends to the outside of the building. This is important if we're to understand the working of air conditioning at even the most basic level.

Air conditioners work in a similar way to how a domestic refrigerator keeps its contents cool. The refrigeration process is the same except a fridge only needs to cool a small space (its interior) while an air conditioner needs to cool a much larger space (a room).

To do that, a refrigerant gas is compressed to reduce its temperature and air is passed through a kind of grid or radiating surface that contains the chilled gas, chilling the air as it is passed through it.

This happens at pressure and since the compressor is a mechanical device, it produces a lot of heat when it's working. That heat is combined with moisture captured from the air and expelled from the unit via a duct or venting pipe or hose.

A fridge just allows the heat to dissipate into the room it occupies, which is why you can feel the heat coming out the back of your fridge, especially in warm weather.

An AC works on a much larger scale and therefore produces a much greater volume of hot, moist air which if allowed to simply escape into the room being cooled, would actually heat it up rather than cool it because it produces more hot air than cold. That's why the heat needs to be vented to the outside of the building.

How Hot Air is Vented Outside

With fixed HVAC installations and ductless mini-split air conditioners (which have the exhaust/condenser part of the process located outside the building), the hot exhaust air is easily vented outside through a permanent vent in the wall.

You probably don't give it a second thought because you don't see it when you're inside enjoying the cool, comfortable atmosphere inside.

With portable units, there is no fixed or permanent vent. So they have a flexible plastic hose that connects to the back of the unit at one end and to a nearby window at the other end. That's what carries the hot air out of the room.

If you don't connect that hose up to a window or out through another vent hole in the wall, you'll just get hot air pumped into the room from the back of the unit and the room will heat up because there is more hot air coming out the back than cold air coming out the front!

The Reality of Vented Portable Air Conditioners

So now you know why an AC needs to be vented and why there is no such thing as an unvented portable, refrigerant-based AC!

All aircon must have a means of venting its hot, moist exhaust air, or it won't cool the space it is intended to cool.

So next time you're looking in hardware stores or seeing the multitude of advertisements online and you see portable air conditioners being described as "ventless" or "vent free" they're either promoting evaporative coolers (they don't produce hot air and so don't need to be vented) and not telling you. Or they're simply outright lying to you so you'll buy an AC that really has got a vent hose anyway!