Air Conditioner Reviews, HVAC info and Buyers Guide

How to Vent a Portable Air Conditioner

by David Parker

For those who’ve never considered a portable air conditioner, the name can be misleading. “Portable” in modern usage, has come to mean “go anywhere.” Unfortunately, for a portable air conditioner, this isn’t quite the case. All air conditioners trade hot air for cold.1 They pump up the temperature in one location and lower the temperature in another. The technology is the same as it is for a refrigerator, and if you’ve ever felt the backside of a fridge, you know it gets pretty hot.

Do I have to vent a portable?

portable window vent kit install example

Let the hot air out. Keep the cool air in. --via

Yes. The hot air generated by a portable air conditioner has to be removed from the room you wish to cool.2 Otherwise, there’s no temperature drop to be had. The hot (and moist) air needs to be vented. The most common way to do this is by running a vent hose (included with all portable air conditioners) out a window. (See below for instructions.) Some people ask, what is a window kit? The window kit is the vent hose and adapters that allow you to let the hot air out, yet prevent cold air from escaping.

But, there are other options. For example, a hole in an outside wall will work just as well, as long as there is a seal so outside air can’t just leak back in. Other options are to vent the portable air conditioner into a subfloor space, an adjacent room or a drop ceiling.3 In some circumstances, the AC can be vented into the main part of the house while keeping just one room cool. This would be unusual, but, for example, someone who has to work in a hot attic might run the AC vent hose into the main part of the house for a few hours while they completed their work.

In most applications, outside venting is the norm and this is the best choice. The reason is simple: wherever the unit vents will have the temperature raised as much as the temperature is reduced where the AC is. You can’t beat physics.

What about a room with no windows? Venting through a wall.

Cutting a hole through an outside wall is an option, limited only by the homeowner’s creativity and ability with simple tools.4 You will have to make sure you are not cutting into anything behind the wall and you will be creating an opening that may have to be resealed (plugged) when the AC is not in use.

  1. Use a stud finder to mark out stud locations. Pick an area between two studs that is large enough for your vent hose to go through. (Vent hoses are typically 5 inches or less in diameter, but extension hoses can be larger.5)
  2. Remove interior wall covering to expose interior wall and any wiring or plumbing running through that area. It is usually better to find another spot if you see wires or pipes rather than trying to reroute them.
  3. Remove any insulation and drill a small hole through to the outside. Stick something through the hole to mark it and check outside to make sure your vent hole is in a location that is unobstructed and not an eyesore.
  4. Using your marker hole as a guide, draw a circle slightly larger than your vent hose on the outer wall. Cut this hole out with an appropriate tool (reciprocating saw works well).
  5. Check the fit of your vent hose and pack around it with soft insulation. You may need to use duct tape to secure the hose (in case it gets bumped). However, it is better to have the hose pull out rather than risk damage if it is pulled accidentally, so do not secure it too well.
  6. The collar from the window adapter kit (provided with the unit) can also be mounted over the hole you cut. The vent hose will fit this collar and the collar will seal the hole in the wall.
  7. Repair the inner wall.

Install with a Window Kit: Normal Installation

Typical portable ac window kit

Typical portable ac window kit

The preferred installation is through a window and manufacturers include materials for this type of venting. Other types of venting may require purchasing adaptors or specialty items.

Installing through a window is as simple as matching the window kit to the window opening and then attaching the portable air conditioner hose to this. The user’s manual for your unit will show different window configurations and how to handle them.

Below is a dual-hose portable install video. Thanks to BigDaveAppliances for the vid!

Odd windows, such as swing type or sliding door types may require some ingenuity. It is usually better to try to use the window kit provided and block off extra openings with cardboard, plywood or Plexiglas that it is to design something new. In any case, understanding that you want unimpeded air flow and a good seal on the vent hose at the window will guide a custom installation.

Other considerations

You must have the proper electrical outlet close enough so that you can both power your unit and vent it properly. This may influence where you decide to vent the unit. Extension hoses, if needed, are available, but should be purchased from the same manufacturer – sizes differ and you cannot guarantee that one manufacturer’s product will fit another’s.

There may be regulations in place that prevent you from installing a permanent window kit on a particular window. This can come up when a window is required for escaping a fire (for example). Install options may also be limited for renters.

In situations where a portable air conditioner is not vented to the outside, it is advisable that the area receiving the exhaust should be as large as possible or vented itself. So, for example, when venting into a subfloor, the subfloor should be vented to the outside somewhere. Failing to provide enough of a “sink” for hot air will eventually impair the ability of the unit to cool.

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