Installing Window Air Conditioning

A window air conditioning unit in a blue house.
What You'll Need
Power drill
Window air conditioner
Foam insulating strips

Window air conditioners are a great way to cool off a room without breaking the budget. These small units come in a variety of shapes and sizes and can be removed when they are not in use. Here are a few simple steps to install a window air conditioner in your home.

Step 1 - Purchase A Window Air Conditioner

Before buying a window air conditioner, you need to make sure the unit has enough British thermal units, or BTUs, for the space. It also needs to fit in the desired window. Once you know the necessary number of BTUs, you should double check that the air conditioner will actually fit in the window. As a rule of thumb, you want at least two inches of space around both sides of the unit.

Step 2 - Prep the Air Conditioner

After you have bought the air conditioner, it is time to unpack it and prepare it for installation. If possible, find a friend to help out. Window air conditioners are not light and having an extra set of hands will make everything easier. With the unit unpacked, attach any side panels, flanges, or rails that came with the conditioner. Follow the manual and use the screw provided in the box.

Step 3 - Prep the Window

Window air conditioning unit in a brick complex.

The air conditioner will likely remain in the window for months, so now is a good time to give the window a good cleaning. You can also use this time to inspect the window and make sure everything is in working order before continuing.

Step 4- Install the Air Conditioner

Once everything is assembled, open the window and slide the unit inside. The window should be high enough that you can slide the air conditioner underneath with ease. Air conditioners usually come equipped with a top and bottom flange, which help hold it securely in place. Position the unit so that the bottom flange runs right against the windowsill. Then lower the window until it abuts the top flange. The flanges should keep the air conditioner in place at this point, but it is a good idea if your helper holds it in place until the installation is complete.

Step 5- Add Angle Brackets

Most air conditioners feature a few angle brackets that help keep the window sashes from coming apart. Along with the flanges, the brackets are key in keeping the air conditioner in place. Start by placing the brackets on the top sash and marking where the screw holes should be placed. Drill a few pilot holes to avoid splitting the wood and tighten the brackets in place. Once the brackets are in place, pull out the side panels (the ones you installed earlier) and screw them into the windowsill. Once you reach this point, you can tighten all of the screws down and make sure you did not leave any out.

Step 6- Add Finishing Touches

A window air conditioning in a brown house.

The final step in this installation is weatherproofing the air conditioner. You want to create a tight seal around the open window so that inside air does not escape. Your unit should have come equipped with some foam insulating strips. These strips should be installed where the top and bottom sashes of the window meet. Measure the foam against the window and cut to the desired length. The foam should fit snuggly in the gap between the two sashes. If your air conditioner did not come with insulation you can always purchase some at your local hardware store. With everything installed, plug in the air conditioner and make sure it is running properly.

Additional Tips

If you need to remove the air conditioner when the cold weather hits, you should store it in a dry room and keep it upright. Some units come with L-brackets, which should be installed prior to placing the air conditioner inside the window.