Must Portable Air Conditioners be Vented Out a Window?

There is some debate as to whether portable air conditioners must be vented out a window or not, so let's look at this conundrum in a bit more detail to see what the answer really is.

The first thing to be aware of is that all air conditioners of all designs produce both hot and cold air, due to the nature of the refrigeration process that goes on under the hood.

The cold air is what we want to be circulating around our room to keep us nice and cool during the hot summer months.

The hot air is absolutely not wanted in our homes during this time of the year!

Removing Hot Air from Air Conditioners

To remove the hot air from the system, air conditioners are equipped with a means of removing it from inside the cooling unit and pumping it outside into the open air.

With fixed AC equipment, that job is fulfilled with ducting that connects the internal cooling unit through walls to the external unit outside (the one with the big fan in).must portable air conditioners be vented out a window

Hot air is produced in the internal unit (compressor/dryer) where moisture from the internal air is also removed. The resulting hot, moist air is drawn through the ducting by the big fan in the external unit and released to the outside air where it is dispersed.

That's how central air systems (HVAC) and also mini-split AC units work to cool the air indoors. Window AC units, PTAC and VTAC units work in a similar way, except all the processing is done in a single contained AC unit with the hot air being exhausted through the wall (PTAC/VTAC) or directly to the outside in the case of window AC units.

How Portable AC Removes Hot Air

Portable air conditioners are a little different, making use of a flexible vent hose that must be connected to an outlet to remove hot air from the room in which they are cooling.

This also holds true for portable self-evaporating AC units, as the need to remove hot air and moisture from the room is equally necessary.

The need for the flexible exhaust hose (or two hoses in the case of dual-hose portable AC units) is of course due to their nature of being "portable," aka not fixed in position. It allows them to be moved from room to room and the hose hooked up to an external wall outlet in the room they are moved to.

Window or Wall Outlet?

The most common way to exhaust the hot air out of a room is through a convenient window. This is mainly because it is quite easy to fix a specially designed outlet vent to a window.

Some new owners of portable AC units may have differing opinions on the ease of installation of the window fixing kit, but it is a lot easier than drilling a hole through an external wall.

In some situations, where a window is not present or not suitable to be used as an outlet, a wall vent will work just as well. If there is already a wall vent in place, the task is very easy. If not, a hole must be made in the wall.

Other Venting Options for Portable AC Units

While a window or an external wall make the best options for venting a portable air conditioner through, there are other alternatives to consider if there is no suitable window or you don't want to (or cannot) drill a hole in an external wall.

If the room has a door that opens out to a balcony, this could be used if no other option exists. The installation may not be so easy, but a professional should be able to undertake the work.


Another venting option is to use a chimney if one is present. This is more likely in older buildings.

However, a long flue must be installed inside the chimney to assure an unobstructed passage for the hot air to escape through. This type of work should be done by a professional.

A viable option is to use existing duct work if it is present, or install fixed ducting through a false ceiling if there is one (more common in offices and commercial premises).

No Vent Option

There is one last option if there is no way to vent a portable AC in a room. That is to buy a ventless air conditioner (evaporative cooler) that doesn't produce any hot air that would need to be vented outside.

However, there are restrictions on this option. You must live in an area where the climate has low average humidity and the room to be cooled must have a window that can be opened to allow for air circulation.


As to the question of whether a portable air conditioner must be vented out of a window or not, the answer is that a window is the best option if one is available, but if not, other options for venting exist.

As long as there is a way for the hot, moist air to escape from the room to the outside, all options should be explored. It is not advisable to simply run a portable AC in a room without any form of venting to the outside.

This is because the hot air will just be exhausted into the room being cooled. Since there is generally more hot air than cold produced. The result will be an increase in the temperature inside the room!

Therefore, a portable air conditioner must be vented to the outside one way or another, with a window being the most convenient and widely used option. It is just not the only option.

Posted: May 5, 2022

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