Can You Use a Window AC Without a Window?

Yes. You can use a window air conditioner without a window by planning for the exhaust of hot air and the drainage of condensate. 

How do you use a window AC without a window? By using one of the creative methods described below.

Note: These methods work for a portable air conditioner too, but window air conditioners are more efficient and come in larger sizes for more effective cooling and dehumidification of the space.

Using a Window AC Without a Window

You’ll need to plan for two physical effects of running air conditioning: Exhausting hot air and draining water out the back (as seen in the lower right corner of the AC in the picture).

Window air conditioner structure

Solving those two problems is vital in understanding how to use a window air conditioner without a window. The methods explained below consider those important issues.

How Can You Use a Window Air Conditioner Without a Window?

Actually, there are several ways to do it, with at least one of them being very similar to the normal installation. There are also some very imaginative ways, which may or may not be something you or other members of your household would be in favor of. So, keeping the important factors of how a window AC works in mind, here are some suggestions for alternative ways to use them without a window.

Through the Wall

There are room ACs manufactured that are specifically through-the-wall ACs. They come with a steel sleeve that fits into the wall space. The AC then slides into place in the sleeve. However, if you have a window air conditioner already, you can turn it into a wall AC.

How to use a through the wall AC: This can be accomplished by cutting a hole in an exterior wall, building a “frame” for the AC unit to rest in, and simply installing it similar to how it would be done in a window, except without the expandable side panels.

Where to use a wall AC: This can work well in a garage, shop, basement, or even in the main living area. Before beginning this project, make sure that the thickness of the wall is not too much so that it will block the outside air vents.  This could cause the unit to overheat and either shut off or even be damaged.

Tips: First, make certain that the unit is slightly tipped toward the outside of your home to allow the condensate to drain outdoors. You can imagine the problems that might occur if it drains into the wall cavity or inside your home. Not good.

Make it airtight. People who have used this method of using a window AC without a window often use caulk or expanding foam to tightly seal around the AC unit inside and out to prevent air and water leakage or insects and other pests from coming in.

Improve its appearance: You also might cut and attach trim boards around the unit, much like a picture frame. Then it can be stained or painted to provide a nice, finished look.

Pros and Cons: You don’t need a window, of course, and the AC won’t be taking up the kinds of space used in the methods below. Plus, the AC can stay in the wall permanently. The downside is that not every homeowner can cut a whole into the wall and frame it up. And hiring a handyman service to do it will cost $300-$500.

More Imaginative (and Unusual) Ideas

OK, through the wall is fairly standard. What else can you do to use a window air conditioner with no window?

Send it Up the Chimney

If you have a fireplace, you won’t be using it during the summer, so why not use it to vent the hot air from your window AC?

Tips: You’re going to have to fix it to the fireplace opening in a fairly airtight manner.

Two important things to remember:

(1) As much of the hot air as possible must be directed up the chimney. This might require that you fabricate a shroud to keep the hot air from escaping sideways into the room. Sheet plastic and quality duct tape can be used.

(2) The condensate must be collected and disposed of. This might be accomplished by sitting the AC on a raised platform or box and collecting the water in a pan under it when it drips out the back.

Pros and Cons: You won’t have to cut a hole in the wall – you’re using an available vent. The negatives are dealing with the condensate without creating a leaky mess. And if you use tape, it may leave a sticky residue. But you can clean it off with Goo Gone or similar cleaner.

House it in a Tote Bin

Use a large storage tote lying on its side to collect the hot exhaust air before venting it elsewhere. A hole is cut in the lid of the tote using the back of the AC as a template, and the AC fits through the hole. The lid is then secured with duct tape to the back of the unit.

A round hole is cut in the side of the tote (facing up), and a large exhaust hose is securely taped over that hole. This exhaust hose is then run into a well-ventilated attic, through a door or wall, or whatever you can come up with as a way to get this hot air out of your living space.

Tip: Insulating the exhaust hose will help reduce heat transfer back into the room. And remember to provide a way to collect the condensate that will be produced.

Think Outside the Box

Once you understand that the most important factors are venting the hot air from the back of the AC out of your home, and capturing the condensed water so it can be disposed of, you might be able to think of more ideas to use a window AC without a window.

Some other places where the exhaust air might be vented are into a range vent or a wood or pellet stove.

One Big Negative – Reduced Efficiency

Aside from the unusual appearance of having a window AC sitting in your living room in whatever odd-looking way you have devised to vent it, there is one other “negative” that you need to be aware of. That is what is known as, “negative pressure”.

The standard way the hot condenser coil is cooled is by outdoor air being drawn into the outside part of the unit and then blown out the back. If the entire unit is indoors, this air will be drawn in from the room air where the AC is sitting. This creates negative pressure in the room, meaning that “make-up air” will be sucked into the room from other rooms, under doors, or any number of other places. The end result is that the efficiency of the AC unit will be negatively affected – perhaps even up to 50% of what it was designed to be.

But it could be that you’d rather have an air conditioner operating at half capacity than no air conditioner at all. If that’s the case, perhaps this article was helpful.

Written by

Rene has worked 10 years in the HVAC field and now is the Senior Comfort Specialist for PICKHVAC. He holds an HVAC associate degree and EPA & R-410A Certifications.

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