How to install portable air conditioner in basement window

When you need to install a window air conditioner in a basement window, it can often be a struggle to get the air conditioner to fit and rest securely in the window. Basement windows are commonly not as uniform as other home windows. This can be a problem when trying to install a standard size window air conditioner. Here are some tips that can help you when you install the air conditioner.

Step 1 - Seal Air Leaks

When installing an air conditioning unit in a basement window, you will oftentimes have to remove window bars and even the window entirely to fit the unit securely. Removing the window will in most cases present a new problem of air leaks as small as a crack to several inches, depending on the size of your window frame.

If there is a bit of space between the window frame and your unit, there are several possible solutions. You can place boards under the unit so that it is resting on the outer sill. Tilt the air conditioner slightly so that it drains properly outside and prevents rust from forming. Another option is to fill the gaps on the side or top with Styrofoam or plywood.

Step 2 - Secure the Air Conditioner

The most important thing about basement air conditioners is that they must be securely in place. That is often the most difficult part about a window unit. If you will be shopping for a new unit, take measurements of your window before you go to the store.

New or used, you may need to make a small shelf for the air conditioner to rest. The shelf should have a slight slope as well so that the air conditioner drains outside. Even with a shelf, you may still have openings around the window. If that is the case, seal them with a small board taped into place. If you have a sliding window, use tape to create a seal along the sliding portion so that you can still open the window if you want.

Step 3 - Secure Your Home

Once you install a window air conditioner unit, your window lock will no longer function properly. To maintain security in your home, cut a board or stick the length necessary to fit between the upper window frame and the top of the sash. Doing so will prevent unwanted intruders from prying the window open and entering your home.

Using these simple tips, you can easily install your air conditioning unit and have it working to its full efficiency this summer. Be sure to thoroughly seal all of the leaks, and you will be on your way to a cool and energy efficient summer.

Don't suffer in the heat with crank out windows! These simple, rental friendly solutions will allow you to have a casement window air conditioner this summer!

Our upstairs rooms have casement windows (also known as crank out windows), making an in-window air conditioner impossible to install. We avoided going upstairs altogether on the hottest days! But I've found three simple ways to set up a casement window air conditioner, to keep our upstairs cool all summer long!

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Central air conditioning is pretty rare in Seattle, since our summers are usually 75 degrees with low humidity (to make up for those dreary, rainy winters!) But the last few summers have been creeping into uncomfortable territory, and when you add in wildfire smoke that forces our windows closed, it becomes unbearable!

Our upstairs is just the playroom and the guest room, so most of the time we just avoid going up there when it gets too hot. But with family coming to visit this summer, I started searching for a way to install a vertical window air conditioner to make our guests more comfortable.

What is a Casement Window?

A casement window is a window that operates on a hinge, instead of sliding on a sash. My window cranks outward, which is nice for catching the breeze but doesn't help when the air is still and hot.

Supposedly, casement windows are more energy efficient and are more soundproof than sliding windows. But I'm not a fan of the design, and plan to switch them out if we ever remodel the upstairs.

Portable Air Conditioners

Portable air conditioners have dropped in price significantly since they first came on the market. Now they're comparable to window units, and way more versatile. I nabbed one of the few left in the store just before our heat wave started!

Instead of mounting the entire unit in the window, a portable air conditioner rests on the floor and uses a vent pointed outside. It's easy to remove the vent when the weather cools down, so you can open the window instead. Unfortunately, the vent brackets won't work with a casement window! 🙁

I needed a way to block out the hot air (and bugs) outside while still allowing for venting for the air conditioner. After some research, here are a few good options for how to put a portable air conditioner in a crank window.

This was my first idea, and it turns out I'm not the only one who thought of this option! I was debating screwing the Plexiglass directly to the window frame, but this video shows how one homeowner replaced his window screen with a custom made Plexiglass insert instead.

This is a great long-term solution, and one that I will probably do at some point once I figure out all the parts. But with the heat wave imminent, I needed something quick and easy!

The downsides to this method are that big acrylic sheets are expensive, and it's difficult to cut a perfect hole for the exhaust vent without cracking. Check out my tips and tricks for cutting Plexiglass if you decide to go this route.

I also had a hard time finding a screen frame that would fit in our windows, and I didn't want to drill permanent holes in our window frame either.

Foam or Plywood Window Insert

This method uses the window vent insert that comes with the portable air conditioner, coupled with a piece of rigid foam or plywood to block the rest of the window. This would also work if you want to install an air conditioner in a sliding window as well. You can see how one homeowner did it in the video below.

This is a fairly cheap and easy solution, but also has its own drawbacks. We only have one window in this room, so blocking off all the sunlight isn't really an option. Plus, a strong gust of wind would knock a foam insert right out! Plywood would require multiple screws to be drilled directly into the window frame.

Fabric Window Seal for Portable Air Conditioners

I stumbled upon this fabric window seal kit on Amazon, and it was cheap enough that I decided to give it a try. This is definitely the most renter friendly option, and a temporary solution that we'll use while I puzzle out the Plexiglass version above.

This casement window air conditioner installation kit comes with a triangular piece of fabric with a zipper down the middle and Velcro along the edges. You also get a roll of adhesive Velcro and large zip ties.

How to Install the Fabric Window Seal

The instructions weren't exactly clear, so I thought I would do a quick tutorial on how I installed the fabric window seal. I apologize in advance for the horrible photos. Taking pictures of a window on a sunny day is hard!

Our window frame was filthy, so I removed the screen and gave the entire thing a good cleaning. This will help the adhesive Velcro stick better.

Apply the Velcro to the window (the part that moves) and the window frame (the part that holds the window in place when closed).

Find the widest point of the fabric, and attach the narrow side to the moving window frame where it opens. Make sure the zippers will be on the inside where you can actually use them!

Work your way around the frame, folding the fabric at the corners to make a 90 degree turn. I had a little extra fabric at the ends, but I just tucked them outside.

Apply the other side of the fabric the same way to the non-moving part of the window.

Then just crank out the window, open the zipper and stick out the vent. I tried to wedge mine between the window and the outside trim so it wouldn't move.

Then close the zipper around the vent, and thread the zip tie through the pull. This keeps the zipper from opening and letting in those pesky bugs!

It's certainly not the most attractive option, but it works! When the weather cools down, I can remove the fabric and put the screen back in about 15 seconds. 🙂 The casement window can still open and close normally, so I can leave the Velcro in place until we need to apply the fabric seal again.

Now that we have a casement window air conditioner solution in place, we can go upstairs on those hot summer days, and our guests will be so much more comfortable!

Check out these other easy home improvement projects!