Are you looking for a good casement window air conditioner or sliding window AC unit for vertical windows in your home?

If so, this guide is for you.

We’ll take an in-depth look at some of the best casement window air conditioners on the market and the best sliding window air conditioners that work for both short and tall windows. We’ll also point out the top features each one has.

In addition to these vertical window air conditioner reviews, you’ll also discover how these popular appliances actually work to cool down a room and about the various types you can choose between.

By the end, you’ll have everything you need to make a well-informed decision on buying the best vertical window air conditioner for your home or apartment.

Table of Contents

Disclosure: Home Air Guides is reader-supported. As an Amazon associate and affiliate for independent brands, we earn from qualifying purchases made through the links on our site. Learn more.

Casement & Sliding Window Air Conditioners Reviewed in this Guide

Here’s a quick comparison chart showing the top casement & sliding window air conditioners. We’ll cover each aspect of these units in the reviews section below, but this gives you an idea of what’s available and an easy way to compare them.

ImageAir Conditioner DetailsPrice
Frigidaire FFRS0822S1 Casement/Sliding Window Air Conditioner
  • Best Overall Air Conditioner
  • 8,000 BTU output
  • 350 square feet coverage
Check Price
Koldfront CAC8000W Casement/Sliding Window Air Conditioner
  • Best for Small Rooms
  • 8,000 BTU output
  • 350 square feet coverage
Check Price
Frigidaire FFRS1022R1 Casement/Sliding Window Air Conditioner
  • Best for Mediums Size Rooms
  • 10,000 BTU output
  • 450 square feet coverage
Check Price
Whynter ARC-14S Vertical/Sliding Window Air Conditioner
  • Best for Large Rooms
  • 14,000 BTU output
  • 500 square feet coverage
Check Price
Whynter Elite ARC-122DHP Vertical/Sliding Window Air Conditioner
  • Best Air Conditioner with Heat
  • 12,000 BTU output
  • 400 square feet coverage
Check Price
PerfectAire 3PASC10000 Casement/Sliding Window Air Conditioner
  • Popular Brand for Casement Windows
  • 10,000 BTU output
  • 450 square feet coverage
Check Price
Global Industrial Casement/Sliding Window Air Conditioner
  • Good Budget Air Conditioner
  • 10,000 BTU output
  • 450 square feet coverage
Check Price
Serenelife SLPAC10 Vertical/Sliding Window Air Conditioner
  • Has the most options
  • 10,000/12,000 BTU output
  • 350/450 square feet coverage
Check Price
Black + Decker BPACT08WT Vertical/Sliding Window Air Conditioner
  • Good for Small Rooms
  • 8,000 BTU output
  • 150 square feet coverage
Check Price
Rollibot ROLLICOOL Vertical/Sliding Window Air Conditioner
  • Best Wi-Fi Air Conditioner
  • 10,000/12,000/14,000 BTU output
  • 275/325/375 square feet coverage
Check Price

Best Casement & Sliding Window Air Conditioner Reviews (Top 10 List)

1. Best Overall Casement/Sliding Window Air Conditioner: Frigidaire FFRS0822S1

Frigidaire FFRS0822S1 Air Conditioner

First up on our list is a vertical air conditioner that fits well into casement windows as well as sliding windows.

We consider this the best casement window air conditioner because it meets most people’s needs when it comes to an effective vertical AC unit. It also impresses on price, room size coverage, and has some good air cooling features. 

You can effectively cool a size room up to 350 square feet, thanks to the decent output of 8,000 BTU. 

The three fan speeds allow you to choose how much airflow you need into the room and you can choose a precise degree on the thermostat. A remote control is also included.

Easily open or close the exhaust with a simple switch. 

It measures 23.5 x 14.2 x 20.2 inches, making it small enough to fit within the majority of casement and sliding windows. 

Check Price and Reviews

2. Best for Small Rooms: Koldfront CAC8000W Casement/Sliding Window Air Conditioner

Koldfront CAC8000W Air Conditioner

The Koldfront CAC8000W is our choice for the best sliding window air conditioner and casement AC unit for small rooms. 

Similar to our #1 review, this vertical air conditioner has 8,000 BTUs out cooling output and can handle a room up to 350 square feet.

This model measures 23.5 x 14.5 x 20.88 inches.

Just keep in mind that your window should have a minimum height of 21.25 inches when using a window panel retainer and 20 5/16 inches if you’re not using one. 

There are plenty of impressive features that come along with this air conditioner such as a digital display, dehumidifier, sleep mode, remote control, and three fan speeds.

Check Price and Reviews

3. Best for Medium Size Rooms: Frigidaire FFRS1022R1 Casement/Sliding Window Air Conditioner

Frigidaire FFRS1022R1 Air Conditioner

Next up is the best casement window air conditioner for a medium-sized room. 

It’s important to know how many square feet your room is so that you don’t buy a unit that’s too large or too small for the space.

The output of this model is 10,000 BTUs, meaning that it is suitable for rooms measuring up to 450 square feet.

The dehumidification setting can remove up to 3.4 pints per hour, making this an excellent option for homes with high humidity. 

Take advantage of the 24-hour timer and full-function remote to ensure that your AC unit is giving you the most convenience that you need.

Check Price and Reviews

4. Best for Large Rooms: Whynter ARC-14S Vertical/Sliding Window Air Conditioner

Whynter ARC-14S Air Conditioner

The Whynter ARC-14S is the best vertical window air conditioner for large rooms. The output of 14,000 BTUs allows this unit to cover areas up to 500 square feet.

Window-mounted units like our first three reviews only come in two sizes: 8,000 and 10,00 BTUs. So if you need something more powerful to cover larger areas, then you’ll want to get something like this.

The Whynter air conditioner is an award-winning portable air conditioner that doesn’t require permanent installation. Simply attach the two hoses on the back to the included window slider kit and place it into a sliding window. This setup will exhaust hot air as the unit runs.

The dehumidifier mode can remove up to 71 pints of moisture each day.

Check Price and Reviews

5. Best with Heat: Whynter Elite ARC-122DHP Vertical/Sliding Window Air Conditioner

Whynter Elite ARC-122DHP Air Conditioner

The Whynter Elite ARC-122DHP is the same brand as our #4 top pick but has the added benefit of heating in addition to air conditioning.

The added heat option on an air conditioner makes it much more efficient and useful as you can use it all year round rather than only during the hottest months.

With an output of 12,000 BTUs, this vertical AC unit can cover an impressive amount of space up to 400 square feet. This is powerful enough to use in a large bedroom, sunroom, or kitchen.

Enjoy a 24-hour timer as well as full control over your thermostat, with a range of 61°F – 89°F for cooling and 61°F – 77°F for heating.

And like our previous review, this AC unit for horizontal sliding windows comes in a portable design with a rear hose and window adapter kit.

Check Price and Reviews

6. Popular Casement Window Air Conditioner Brand: PerfectAire 3PASC10000

PerfectAire 3PASC10000 Air Conditioner

The PerfectAire 3PASC10000 is from a very popular brand that always seems to be selling out quickly. So if you’re interested in this casement window air conditioner, then you should buy it while you can.

This AC unit can cover up to 450 square feet thanks to the 10,000 BTU output. 

It can be used for both sliding or casement windows thanks to the expandable window mounting kit that comes included in the box.

With three fan speeds, you can turn up or down the cooling power as you need. It also has an automatic fan speed mode that works with the internal thermostat to adjust itself for maximum cool efficiency.

An Energy Save mode is also included for lower electricity usage. Plus, an innovative “Follow Me” feature turns your remote into a portable thermostat. That feature alone makes it the best vertical window air conditioner for many people.

Check Price and Reviews

7. Good Budget Sliding Window Air Conditioner: Global Industrial

Global Industrial Air Conditioner

If you don’t want to spend a lot of money on an air conditioner for horizontal sliding windows or casement windows, then the Global Industrial unit could be the best option for you. 

Along with the impressively low price you can benefit from the good room size coverage of 450 square feet thanks to the 10,000 BTU output. 

There are plenty of user-friendly features to take advantage of as well, including a sleep mode, auto restart, 24-hour timer, and Follow Me remote that acts as a portable thermostat.

Like our previous review, this model also includes an Energy Saver function for low electricity costs without sacrificing your cooling comfort.

Check Price and Reviews

8. Top Vertical Window Air Conditioner with the Most Options: Serenelife SLPAC10

Serenelife SLPAC10 Air Conditioner

Options are invaluable when it comes to air conditioners, much like most things in life. And the Serenelife SLPAC10 offers you four different models to choose between to get the perfect vertical window AC unit for your needs.

Being able to choose the BTU output and the features that you want your sliding window air conditioner unit to come with gives you much more customization than any other options on the market.

With the Serenelife SLPAC10 you get these choices:

No matter which option you choose, you can benefit from the power of a portable air conditioning unit that can easily be moved from one room to the other when you need it.

Plus, the automatic swing mode sets the air vents up to move left and right for maximum air circulation. This can help to prevent hot spots that most every room tends to have.

Check Price and Reviews

9. Good Vertical Window Air Conditioner for Small Rooms: Black + Decker BPACT08WT

Black + Decker BPACT08WT Air Conditioner

Another good vertical window air conditioner for small rooms is the Black + Decker BPACT08WT. It has 8,000 BTU output and a coverage of 150 square feet. 

It’s good for small bedrooms, offices, and bathrooms where a window air conditioner will not fit.

This sliding and casement window air conditioner includes wheels that can be very helpful when transporting the unit from room to room or readjusting it while it’s in place. 

The window adapter also allows you to install it into your sliding or casement window with ease. Setup and take down can be done in a matter of seconds.

As for cooling, this unit combines three energy efficient functions for your convenience: cooling, fan, and dehumidification. It also has a bucket-less, self-evaporating design that expels collected moisture out the exhaust hose. This makes your living space cool, clean and dry without any effort on your part to maintain it.

Check Price and Reviews

10. Best with Wi-Fi: Rollibot ROLLICOOL Vertical/Sliding Window Air Conditioner

Rollibot ROLLICOOL Air Conditioner

The Rollibot ROLLICOOL is one of the best sliding window air conditioners on the market when it comes to every factor: smart Wi-Fi control, no need to permanently install it into the window, portable wherever you need AC the most, and much more. 

This portable air conditioning unit also comes in three different sizes so that you can choose the best option for your space:

The Wi-Fi capabilities allow you to control the air conditioner on your smartphone or tablet, from anywhere in the world. This can be beneficial for the hottest days when you want to turn your AC unit on before you get home so that you can walk into a freshly air-conditioned space. 

You can also set up personalized cooling schedules throughout the week so that the air conditioner runs automatically for you.

It really is the best casement window AC unit and sliding window air conditioner with smart controls that you’ll find today.

Check Price and Reviews

Vertical Window Air Conditioner Buying Guide

What is a Casement Window Air Conditioner?

A casement window air conditioner is one that fits into a casement window rather than a double hung window. A casement window is that which opens outwards or inwards by a handle on the side of the window and hinges on the other side.

Casement window air conditioners are mounted vertically rather than horizontally. Horizontal AC units tend to be the norm on the market which is why it is so important to make sure that you are purchasing the correct AC unit for your window. 

You cannot use a horizontal AC unit in a casement window, and vice versa. 

What is a Sliding Window Air Conditioner?

A sliding window air conditioner is one that fits in a sliding window or door. It is mounted vertically to fit the open window space. For this reason, they are often called vertical window air conditioners. However, some people do refer to them as horizontal window air conditioners because sliding windows open horizontally. 

Sliding windows do not open outwards or inwards, but instead, they are made up of two panels of glass. One of these will slide against the other as it is opened to save space and an aesthetically pleasing look. 

There are two types of AC units that you can choose for a sliding window: a vertical window AC unit or a portable AC unit. We’ll be looking at both of these options later in this guide.

Casement Window vs Sliding Window

While both casement windows and sliding windows take the same type of air conditioning unit, they are still two completely different types of windows. For starters, sliding windows are wider than they are tall while casement windows are the opposite. 

Sliding windows open horizontally while casement windows open by swinging either outwards or inwards. This helps casement windows open completely, allowing more air to pass through into the house. However, with sliding windows, only half of the window will open and therefore less air will be able to make its way into space. 

Whether you have casement or sliding windows will depend on your property, the space that the windows fill, and the stylistic design that was used when creating the build.

Horizontal Window Air Conditioner vs Vertical Window Air Conditioner

Horizontal window air conditioners are the traditional models that fit in vertically sliding windows called double hung windows. These are different from vertical window AC units as they are installed horizontally and are made up differently. 

Horizontal windows will have wider widths and shorter heights than casement windows, which will have thinner widths and taller heights. Sliding windows are still considered vertical windows but they have a much more substantial width due to the window opening horizontally. This space is where the AC unit will be installed, so manufacturers for both of these types of units take this into consideration. 

This can be seen by the standard window widths for both of these types of units. We’ve listed some of these standard window sizes below to help you understand this concept.

Horizontal Windows Vertical Windows
Double-Hung Window Widths Sliding Window Widths Casement Window Widths
24 inches 36 inches 35 inches
28 inches 48 inches 47 inches
32 inches 60 inches 59 inches
40 inches 72 inches  
44 inches 84 inches  

As you can see, sliding windows have a much wider width than casement windows or even double hung windows. Casement windows often come with a much smaller width because they are designed to be taller windows. 

So horizontal window air conditioners will be wider than they are tall. Casement air conditioners will be taller than they are wide. While you might think that horizontal AC units would be better for sliding windows, vertical units are used instead. This means that they will also be taller than they are wide. 

Types of Vertical Window Air Conditioners

Vertical Window AC Units

Vertical window units are otherwise known as casement window AC units and can be seen on our list in the first and second reviews: Frigidaire FFRS0822S1 and Koldfront CAC8000W Casement/Sliding Window Air Conditioner

These AC units are installed into the window and have a taller height than their width. They are designed to be kept within the window frame rather than being taken out repeatedly. This can be seen with all the hardware that comes with the AC unit to install it permanently onto your window frame. 

Portable Window AC Units

Portable window AC units can be installed into a window through a hose, but they can also be removed and used in different places. Portable units can be transported to different locations depending on where you need AC the most. 

For tall sliding windows or doors, you can purchase a window extension kit to make the window adapter longer. Most included kits fit standard size windows between 24 to 40 inches and the extension can make it fit 80 inches for the sliding door height.

Choosing the Right Size Casement & Sliding Window AC Unit

Best Casement Window Air Conditioner

You need to choose the correct size for your casement or sliding window AC unit, but this means more than just the measurements of the unit. You also need to consider the BTU output and square footage that the AC unit can cover. 

Casement and sliding window air conditioners only come in two sizes of output: 8,000 and 10,000 BTUs. These can cover rooms sized 350 to 450 square feet. 

If you need something smaller or larger than this, you should consider a portable air conditioner as these come with a more versatile range of BTU outputs. 

Below is a quick table to show you what BTU output you’ll likely need depending on the square footage of the room. Bear in mind that this is a rough guide as some AC units can cover more or less space than the BTU output might suggest. 

BTU Capacity for Casement & Sliding Window AC Units

Room Area To Be Cooled BTU Capacity Needed
up to 350 square feet 8,000 BTU
350 to 450 square feet 10,000 BTU
450 to 550 square feet 12,000 BTU
550 to 700 square feet 14,000 BTU

Features to Look for in a Casement/Sliding Window Air Conditioner

Fan Speeds

Many air conditioners offer different fan speeds for you to choose from to adjust how many RPMs the fan will be working for at any given time. Running your fan at a slower speed allows the compressor and the coil more time to dehumidify the air, rather than just cooling it. 

If you were to run the fan at a higher speed, the air will be cooled faster but less humidity will be removed from the air. So, having an AC unit with more fan speeds gives you a better number of modes to run your AC unit at. 

Energy Saver Mode

An Energy Saver mode is always worth looking for when choosing the best AC unit for your needs because it can reduce your energy consumption while still effectively cooling the air in your space. 

Energy saver mode helps reduce power consumption by automatically turning off the circulation fan as well as the exhaust fan when the compressor is off. The air conditioner will automatically cycle both fans on and off with the compressor as needed for cooling.

This means that the AC unit is not always running, saving you money in running costs, and also prolonging the life of your unit as it is not always running at maximum capacity continuously.  

Exhaust Slider

An exhaust slider is a switch found on some vertical air conditioners. The slider allows you to either close or opens the exhaust. 

Opening the exhaust allows air to vent from inside your home to the outside, allowing more fresh air to come in from outside.

If you keep the exhaust closed; however, it keeps the current air inside your room to continue circulating without new fresh air. 

Keeping the exhaust slider open will allow fresh air in, but your AC unit will have to work harder to cool this new air as it comes in. Keeping the exhaust closed will allow the AC unit to work less as the air circulating has already been cooled. However, this might become stale and more unpleasant than fresh air.

You’ll need to experiment with this function to find out which selection you prefer: an opened or closed exhaust switch.


Most air conditioners will also be dehumidifiers as well, as air is drawn through and across a cooling coil that evaporates moisture in the air and collects it in a bucket. The air is pushed back out into the room, both colder and less humid than it started. 

It’s worth looking at how much dehumidification your AC unit can hold before it needs to be emptied. Choosing a model with a bucket that cannot hold a large amount of water will not be ideal for someone living in a high humidity area.

Some air conditioners have an auto-evaporation function that expels the collected moisture out the window so you don’t have to empty a water collection bucket.

Digital Controls

Digital controls are always beneficial when it comes to AC units as they allow you to adjust the settings much more accurately than traditional manual rotary dials. 

Digital controls also often come with an LCD display that will show you the exact temperature or setting that you’re running your unit on. Units without digital controls will not have this and often leave you guessing at the exact temperature. 


A timer allows you to set the air conditioner to either turn on or off after a certain amount of time so that you can enjoy the cooled air without worrying about running the unit for too long. 


A remote control is not necessary when it comes to choosing an air conditioner, but it does come with a lot of added convenience. You can control all of the settings without having to be near the unit.


More advanced AC units will have Wi-Fi capabilities which allow you to control the unit from your smartphone. Some models also let you connect the unit to a smart home device like Amazon Alexa or Google home for voice control.

Common Questions About Vertical Window Air Conditioners

Best Vertical Window Air Conditioner

What is the casement of a window?

The casement is the part of the window that opens, securing the glass panel in place along with a hinge fixed to the window pane. If a moving pane of glass does not have a hinge, it is considered a sash rather than a casement.

How does a casement window air conditioner work?

A casement window air conditioner works just like any other window AC unit on the market, by using refrigeration properties to expel heat and humidity from the room while pushing cooled air into the room to circulate. 

The basic components of a casement window AC unit are as follows: a thermostat, a fan, a compressor, a refrigerant, an evaporator coil, and a condenser coil. 

The thermostat registers when the room has reached a certain temperature and triggers the fan. The air from the room is pulled into the unit and passed over the cooling coil. The air is then pushed back into the room, now cooled and rid of some of its original moisture.  

How do you put a window air conditioner in a crank window?

Below are the listed steps of how to place a window air conditioner into a crank window. 

  1. Open the window fully. 
  2. Remove the screws of the stopper. 
  3. Use a screwdriver to remove the operator control arm from the bracket. 
  4. Remove the hinge arm by unscrewing it from the window frame. 
  5. Take off the hinges from the window frame, being careful not to drop the casement.
  6. Add the mounting brackets with your socket wrench. 
  7. Position the air conditioner in the window frame so that the inside of the bottom lip is touching the windowsill. 
  8. Use the mounting brackets to attach the AC unit to the window, using the bolts or screws that came with your installation kit. 
  9. Fill the gaps on either side of the air conditioner either with cut pieces of wood or the side extensions. Secure these to the window frame. 
  10. Cover the top and bottom edges with a foam-rubber sealant to avoid drafts. You have now placed a window AC in a crank window. 

Can you put an air conditioner in a casement window?

You can put an air conditioner in a casement window as long as you have the correct type of window air conditioner. It must be either a vertical AC unit or portable AC unit with the correct mounting equipment. You’ll also need to make sure that the air conditioner is the correct size for your window so that it fits properly. 

Can window air conditioners be mounted vertically?

A window air conditioner can be mounted vertically as long as you use a vertical air conditioner type. However, if you have a horizontal air conditioner, you cannot run this on its side. The components will not work effectively and there is the possibility that the moisture that has been evaporated from the air will seep into the internal components and reduce their lifespan. 

Can you install a window air conditioner in a sliding glass door?

You can install a window air conditioner in a sliding glass door if you mount it properly. You will need material to block the gaps above the air conditioner such as wood or plexiglass.

Can portable air conditioners work in casement windows?

A portable air conditioner can work in a casement window as long as the window adapter kit is the correct height to fit in the open casement window space. Most portable air conditioners come with window mounting kits that you can use to fit into the casement window.

What is the most reliable window air conditioner brand?

Frigidaire is the most reliable window air conditioner brand for a number of reasons. The brand has been dominating the market for many years now and has never released an AC unit that hasn’t performed well. That is why this brand is highly sought after. 

The brand excels in terms of price, BTU output, and additional features that they offer in window air conditioners. Frigidaire also offers good warranties for all of their products in case something goes wrong and is the fault of either the parts or labor. They also often offer longer warranties for the sealant system to give you peace of mind that your purchase is protected should something go wrong. 

How to Install a Vertical Window Air Conditioner

Installing a vertical window air conditioner is as easy as installing any other air conditioning unit into a window. We have listed the steps below for your convenience. 

  1. Install the mounting hardware: Unlike horizontal windows that use the sash to keep the AC unit in place, a vertical unit needs mounting hardware to accommodate this. Install the mounting hardware to the base of the window or how the manufacturer has indicated in the user manual.
  2. Align the vertical air conditioner: Place the air conditioning unit in the window so that the mounting hardware is in the correct position to secure the unit. You might want to enlist the help of another person here to make sure that you don’t drop the unit.
  3. Secure the unit: Use the hardware to secure the unit in the window. Use all of the hardware that came with your mounting kit to ensure that the unit is as secure as it can be. 
  4. Fix the window: If you have a sliding window, you should place a block of wood or plexiglass between the unit and where the window would normally slide so that no open space is left.
  5. Seal the cracks: Now you need to create an airtight seal with rubber sealant around the parts of the air conditioner that touch the window. You also need to pull the extenders out from the AC unit and secure these onto either side of the window. 
  6. All done! Once there is an airtight seal, you can turn the unit on and enjoy a freshly cooled room.

Enjoy Your New Casement & Sliding Window Air Conditioner

Best Sliding Window Air Conditioner

We hope you enjoyed this detailed guide on choosing and comparing the best casement window air conditioners and sliding window AC units.

As you learned, there are various types of vertical window air conditioners on the market to meet your needs. You can choose the standard compact window AC unit or a portable air conditioner for sliding windows and doors.

The best sliding window air conditioner for your purposes will depend on the size of the window, how it opens (vertically or horizontally), and your budget.

Hopefully, the information provided here on the best vertical window air conditioners has helped you narrow down the perfect little AC unit for your home or apartment at a price you can afford.

Avatar for Patrick Holmes

About Patrick Holmes

Patrick is a Senior Air Quality & Comfort Specialist. He conducts in-depth research and analysis for our product reviews and buying guides in order to offer expert recommendations for people who are seeking to improve their indoor air quality and comfort. (See Full Bio)