Window Air Conditioners for Casement Windows

If your home has the type of windows that slide open from side to side, one of the specially designed window air conditioners for casement windows is a great option to keep you cool in summer.

They are often called sliding window air conditioners by homeowners and are perfect for cooling rooms in the home where there is no central air system.

The downside is that casement window air conditioning units are made by very few brands, but there are some good quality, well known models to choose from.

I'll explain what a casement AC, also known as sliding window air conditioner, is.casement window air conditioner

What is a Casement Window Air Conditioner?

These cooling units have a number of similar names, but I'll stick with the most descriptive of those to avoid confusion.

Window air conditioners can be installed in casement or gliding/sliding windows depending on the type of window they are designed to fit.

In this case, since the window opening is taller than it is wide, vertical window air conditioning units are made in similar dimensions to fit the available space.

The installation is much the same as with horizontal window units, except that the kit comes with material to fill in the space between the top of the window and the vertical window AC unit.

Note: These AC units are not made to fit in single- or double-hung windows that open vertically.

Advantages of Vertical Window Air Conditioners

The main advantage to vertical casement window ACs applies to homeowners that have sliding windows in the rooms they need to cool in summer and no central HVAC.

These units are specialized for such installations and are only really needed when the window opening won't accept a regular window AC unit.

What Features are Needed

The amount of features you'll need really depends on the intended use of the unit. For example, if you are looking to save money and don't need a timer, a unit with basic features is the best option.

If the AC is installed in a bedroom, you will usually be at home a good hour before you decide to hit the sack. So you can just turn it on when you get home and by the time you go to bed, the room will be cool.

If you are thinking about comfort and a moderate level of features in an AC unit, there are a nymber of many modes that allow you to select the best comfort setting for your indoor climate conditions, such as Cool/Dry/Fan.


For convenience, a program function to turn on using the timing device is really handy, especially if you tend to come home at different times. The unit doesn't need to be on constantly, but it will still provide cool air whenever you want it.

Innovative thermostats are very useful if you like to balance comfort with economy.

Some units feature the ability to use a fan speed that is high to cool you down initially, then slow down to maintain an even temperature thereafter. To maximize your comfort and keep you from getting chilly, the AC might select a higher fan speed and temperature if you are close to it.

Dry mode, or dehumidification for cool and damp days is an additional feature that is available on some slider window conditioners.

Check out this article if you need to compare window air conditioners with portable AC.

Power Output

With the more restrictive choices available, these units only come in two power output ratings. These are 8,000 BTU and 10,000 BTU.

There are some factors that may alter your choice of power output, such as whether the room is shaded (less cooling power needed) or in direct sunlight (more cooling power needed), if the room has low or high ceilings (more volume requires more cooling power) or if the room is sparsely or heavily furnished.

Here are two examples of how to size a window air conditioner to suit specific rooms.

20x16 bedroom = 320 sq. ft. The 8K unit works well in a room that is partially shaded. A 10K unit is best if the room is sunny and warms in the afternoon heat.

16x12 kitchen = 192 square feet. This space normally requires a 6,000 BTU window conditioner, but an 8,000 BTU unit is the lowest power option. However, if the stove and range tops are used frequently, more cooling power would be an asset.

A 10,000 BTU AC unit is a better choice if the kitchen is larger than 300 square feet.

Sliding Window Air Conditioner Installation

It is important to be aware that these units tend to be very heavy. You might consider having someone help you to lift the AC and hold it in place when needed.

Check the box to ensure that all necessary supplies are included. For an explanation of how to install your sliding window AC, please refer to the instructions.

Any parts that need to be attached to the AC should be attached first. Take measurements to determine the size of the window panel, which is the material placed between the AC and the top of the window frame. Then cut it to size.

The window panel is the material.

This is important to do before you start the installation, just in case the material supplied is not big enough to fill the gap if you have a very tall window.

Weatherstripping is used to seal any air gaps between the AC and the wall.


When you need a specialist size air conditioning device to fit in a sliding window, these units are a perfect solution.

They don't cost any more than their horizontally installed versions and enable you to enjoy cool comfort during the heat of the summer.

Posted: December 1, 2021

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