Installing an Air Conditioner in a Window That Barely Opens

Around here, air conditioning is almost never part of a deal when you buy or rent an apartment. I converted a spare bedroom into an office, which was great until the sun hit and it turned into a virtual sauna.

In getting an AC unit installed, I was faced with an interesting problem: I had windows that opened up and out at an angle, but just barely. The glass is held in place by metal framing, making it intractable to drill through.

I contacted a few self-described handymen who quoted me anywhere from 50 to 500 dollars and proposed building mounts out of wood, metal, or just plain crazy gluing the AC unit to the frame (!). No two quotes proposed the same solution. That’s when I knew the experience I could hire to solve the problem would be improvising on the job. I had an idea of my own which was cheap and easy to test, so I decided to try it out.

The approach? Industrial strength Velcro® and acrylic glass.

I recently had success mounting rear speakers on stands with Velcro. This isn’t the stuff you kept your shoes on with in second grade. Industrial strength Velcro is at least two inches wide and comes in rolls measured by the foot. The rear side has very sticky glue and can easily attach to the metal frame of your window.

Here’s the finished product, with instructions below:

The total cost was under $40, took two hours, and has worked for me for two summers. I can remove the acrylic glass by tearing away at the Velcro in seconds, making end-of-season take down a five minute chore.

Here is what you need:

• One sheet of acrylic glass — large enough to cover the entire open window.
• Industrial Velcro to run up the sides of the window. The wider, the better. More on this later.
• A circular saw to cut the acrylic glass, or if you’re like me and don’t have a workbench, a scouring knife and some personal tenacity.
• A floor AC unit. Window mounted ones will not work, as they need to hang out too far and will interfere with your barely-opening window.

Step One

Mount the plastic exhaust panel on your window. Your AC panel instructions will tell you to screw it into the wall. This is intractable — we want to avoid damaging our windows by drilling into metal. Instead, throw down a few inches of that sweet, sweet Velcro and the exhaust panel stays in place:

Step Two

Measure your window and cut the acrylic glass to fit.

Unfortunately, I didn’t have a workbench, and didn’t feel like making my way to the ‘burbs to use one, so I used a table on my deck. I scoured the glass with a scouring knife and filed the edges down. This was not easy, and I was punished for my laziness and impatience by grinding away for almost an hour.

The glass:

The scouring:

Step Three

Now that your acrylic glass is cut to fit and filed down for smoothness, attach Velcro to the edges and mount it in the window. You want it to fit in so that it is overlapping the metal frame on the top and sides, with the bottom seating directly into the AC exhaust mount.

Here’s a closeup of Velcro mounted to the metal window edge:

Bonus Tips

At this point, you can fire up the AC and breathe again, but you should keep these tips in mind:

• If you have a wide enough window, consider getting an AC unit that draws its air from outside instead of from in your house. AC units with two pipes are always going to produce a colder room than one. Otherwise, you are drawing warm air from the rest of your apartment when your AC creates a vacuum by expelling the hot air you are aiming to remove from your room.
• You want your Velcro to be as wide as possible. When the sun hits the metal frame, it heats up and some of the glue will melt. If you’ve done your job, you should have a very firm and sturdy acrylic frame, but after a couple of years, the glue will be tired and you will need to replace the Velcro.
• Seriously, scouring acrylic with a knife is a pain. Get a table saw.