5 Best Sliding Window Air Conditioners

We recommend the ONLY sliding window air conditioners worth knowing about. Get the perfect model for your home today with our comprehensive guide.

sliding window air conditioners

There are lots of sliding window AC units on the market, in a choice of sizes, working capabilities and price ranges, so you’re sure to find one that suits your requirements.

Of course, if you’ve never bought a vertical window air conditioner before (or a horizontal AC), you could probably do with some advice to point you in the right direction.

In our buyer’s guide, you’ll find all the information you need to choose the right sliding window AC for your home. 

We’ve recommended the best products on the market today and our comprehensive reviews save you the time and hassle of having to do any more research yourself.

Are you ready to cool down? Then it’s no sweat – we’ll tell you everything you need to know!

Some of the links below are affiliate links, meaning, at no additional cost to you, we may make a commission if you click through and make a purchase.

The Top Window AC Models Compared

See how the top sliding window air conditioner compare in the table below.

There's a key that explains all the table contents below.



Koldfront WAC12002WCO 12,000 BTU 115V Window Air Conditioner


EdgeStar Koldfront 12,000 BTU

Price: $$

Energy Efficiency: 12

Room Size: 500 ft2

Warranty: 2 years

Frigidaire FFRS0822S1 8000 BTU Heavy-Duty Slider Casement Window Air Conditioner

Frigidaire FFRS0822S1 8,000 BTU

Price: $$$

Energy Efficiency: 10.9

Room Size: 350 ft2

Warranty: 2 years + 5 years compressor

Frigidaire FFRS1022R1 10000 BTU 115-volt Slider/Casement Room Air Conditioner

Frigidaire FFRS1022R1 10,000 BTU 

Price: $$$

Energy Efficiency: 10.4

Room Size: 450 ft2

Warranty: 1 year + 5 years compressor

hOmeLabs 5000 BTU Window Mounted Air Conditioner

hOmeLabs 5,000 BTU 

Price: $

Energy Efficiency: 11.1

Room Size: 150 ft2

Warranty: 2 years

Frigidaire FFRA0511R1 5, 000 BTU 115V Window-Mounted Mini-Compact Air Conditioner

Frigidaire FFRA0511R1 5, 000 BTU

Price: $

Energy Efficiency: 11.1

Room Size: 150 ft2

Warranty: 2 years + 5 years compressor

Table Key:

Energy Efficiency: This number is called the Energy Efficiency Ratio (EER). It's the ratio of energy used to cooling power. The higher this number the more energy efficient the AC unit is.

Room Size: This is the maximum area in square feet that the device can comfortably cool.

The Best Slider Window Air Conditioner Reviews

Now, we take a closer look at each of our recommended casement AC units. Find out all the details and what we think and why.

EdgeStar Koldfront 12,000 BTU    *** Our Top Pick ***

If you’re struggling to keep your home cool during the summer heat, the EdgeStar Koldfront 12,000 BTU air conditioner is a great choice.

It can supply a space of a maximum of 500 square feet with plenty of cooling power, so whether you want to cool down your living room, home office or bedroom, you’ll have no difficulties.

This narrow window air conditioner is compact yet really powerful. It’s surprisingly simple to install, and since it can fit any window between 23 and 36 inches in width and with a height of 15.5 inches or higher, it can accommodate most needs.

You won’t need to exert yourself to actually manually adjust the settings thanks to the included remote control which allows you to alter the operational settings from as far as 16 feet away.

It has been Energy-Star certified so you can save on your bills while still staying comfortable during the hotter days of the year. The Energy Efficiency Ratio (EER) of 12 is really impressive and makes this the most energy efficient window AC unit around.

Further energy-saving features include a thermostat-controlled operation, a sleep mode and a check filter indicator so you can maximize your savings. The sleep mode is especially beneficial. It periodically adjusts the temperature by 2 degrees Fahrenheit before going back to the chosen temperature after 6 hours.

There are three different fan speeds to choose from so you can get your optimal level of cooling and, as an added advantage, there’s also a dehumidifying function which will cleanse the room from any excess moisture. This will help your environment to stay healthy and mold-free.

How does it compare to the rest?

Very favorably! This sliding window AC unit is one of the best in the business. For starters, it's Energy-Star certified for being one of the most efficient models of its kind. The EER rating of 12 beats the competition hands down. 

It'd also impressively priced. Despite being the most powerful and most efficient model on this list, it's not actually the most expensive. It's in the mid-price range which makes it a great value purchase.


  • Dehumidifier function
  • 3 fan speeds
  • Energy saving features (Energy Star Certified)
  • Cools spaces of up to 500 square feet
  • Remote control operation


  • Louder than some rival models

  Bottom Line: It's hard to beat this gem from EdgeStar. Price-wise it offers great value for money, and performance-wise it's powerful and efficient. This is the window AC that we recommend over all others.

Frigidaire FFRS0822S1 8,000 BTU

If you’re looking for an ideal cooling solution for your room measuring a maximum of 350 square feet, this air conditioner for a horizontal sliding window ticks all your boxes.

Designed specifically to fit in a casement-style window, this 8000 BTU 115V conditioning unit couldn’t be easier to use. Its electronic controls enable the user to select options easily with a single touch of the button.

If you prefer to control your unit from a distance – and who doesn’t when the weather’s too hot to move – you’ll lovely the fully functioning remote control. It allows you to control the fan speed and temperature from anywhere in the room without ever having to get up from your sofa.

The multi-speed fan has three speeds to choose from to give you the ultimate in cooling flexibility, while the four-way air direction controls enable you to choose exactly where you want to direct the cool air.

You can rest assured that your home will stay comfortable and healthy thanks to the integral mesh filter. It can be slid out and washed to reduce room odors, airborne particles and bacteria in your space.

Whether you suffer from allergies, asthma, or whether you’re just concerned about your indoor air quality, this horizontal window air conditioner will help you maximize your well-being. Since it also runs really quietly, you won’t need to worry about your sleep being disturbed.


  • Quiet running
  • Washable mesh filter for reduced bacteria and odors
  • 4-way air direction controls
  • 3 speed fan
  • Remote control


  • The energy-saving setting isn’t great

  Bottom Line: Overall, we think this is a really great choice of casement window air conditioner if you’re looking for simplicity, convenience and function. Your room will stay cool and you won’t be disturbed by loud running.

Recommended Reading: Don't miss our guide to the top performing quiet & portable AC models!

Frigidaire FFRS1022R1 10,000 BTU

Frigidaire’s casement window air conditioners are known for their high quality and excellent performance. This one won’t disappoint.

Having been specially designed for installation in sliding and casement windows, this model comes complete with an installation kit so you can get straight on with fitting it in your window.

This 10,000 BTU unit is capable of cooling a space measuring up to a maximum of 450 square feet. It also has a dehumidifying function which is capable of removing as much as 3.4 pints of excess moisture every hour. This is excellent news if you need to guard against mildew and mold build-up in your home.

This slider window air conditioner comes equipped with electronic multi-speed controls while the 24 hour on and off timer makes it easy to ensure your room is the perfect temperature when you get up in the morning or when you come in from work in the evening. There is also a fully functioning remote control so you won’t need to physically adjust the controls.

There are several modes to choose from – the auto-cool function, a sleep mode and an energy saving mode – so you can reduce your bills while still benefiting from maximum cooling. There is also four-way air direction so you can get the cool air to every part of your room in the most effective way.

You won’t need to worry about bacteria in the air – there is an integral mesh filter which can be removed and washed at regular intervals. You’ll have a healthier living environment and allergic reactions and respiratory problems will be reduced. There is also an alert letting you know when it’s time to check the filter so you can keep your unit running as efficiently as possible.

This Frigidaire unit can be used in windows of between 21.5” and 40” in height and with a minimum width of 15.5”.  Whether you’re using it in a living room or bedroom, you won’t need to worry about being disturbed, since the quiet operation of this cooling unit makes it very unobtrusive.


  • Quiet operation
  • Removable and washable mesh filter
  • Cools spaces up to 450 square feet
  • Dehumidifying function
  • 24 hour timer
  • 4-way direction and multi-speed controls


  • Very small display makes it difficult to read the LED lights

  Bottom Line: Convenience and multi-functionality come as standard with this air cooling unit. You can benefit from a healthier home environment thanks to reduced bacteria and mold build-up while also reducing your energy bills and keeping your home comfortable. If you’re looking for a reputable brand, this could be the perfect model for you.

hOmeLabs 5,000 BTU

If you have a smaller room which could benefit from cold window air conditioning, the hOmeLabs 5000 BTU window air conditioning unit is a strong contender. Capable of cooling indoor rooms of up to a maximum of 150 square feet, this is a great choice for compact homes and could help to cool down your dorm room, bedroom or living room easily.

This model comes complete with everything you need to install it. You’ll get support brackets, a filter, window sealing foam, a drip-free installation guide and leaf guards as well as the unit itself. The power cord is extra-long, measuring a full six feet, so you’ll find it easier to find an appropriate power outlet.

When it’s hot, you don’t want to have to wait until your room cools down. This model makes short work of cooling your space. It has a super-speedy cooling time and it also boasts a quiet operation so you won’t have your leisure or sleep time disturbed.

There are seven different temperature settings to choose from, giving you complete flexibility, while the adjustable low or high fan speed and two way air direction control lets you reduce the temperature powerfully and rapidly in your small room. You should reach optimal temperature in just 15 minutes at the most.

There is an inclusive antibacterial filter which can be washed using dish soap and warm water or even cleaned with a vacuum cleaner. It can then be reused to improve the cooling power of your unit. With all of the debris clogging up your system, you’ll also find your living environment is much healthier and if you experience respiratory problems or allergic reactions, these should be minimized.

You can use this model on windows with a minimum of 13” in height. This is much smaller than many of its rivals, making it a perfect choice for even the narrowest of windows. It can accommodate windows between 23 and 36” in width.

This is a very safe cooling unit thanks to the backflow drainage which guards against any water soaking its motor or dripping inside your home. Not only will you stay well protected, you’ll also cut your energy bills. This model not only has a lower power start up, but it also has a 11.1 Energy Efficiency Ratio.


  • Safe backflow drainage
  • 11.1 Energy Efficiency Ratio
  • Washable and reusable filter
  • Ideal for use on very narrow windows
  • Comes with a complete installation kit


  • This model has a much lower square footage cooling ability than its rivals

  Bottom Line: If you only have a very small space to cool down or if you only have extremely narrow windows, this model is the one for you.

Recommended Article: In need of a tiny AC unit? We've got the perfect guide for you here.

Frigidaire FFRA0511R1 5,000 BTU

If you’re looking for a compact air conditioning window mounted unit, this 115V 5000 BTU model from the ever-popular Frigidaire brand gets the job done admirably. It comes supplied with its own convenient window mounting kit and is capable of cooling your smaller room rapidly.

As long as your space isn’t bigger than 150 square feet, you’ll have no difficulties in using this unit. It also offers the benefit of dehumidification, removing as much as 1.1 pints of excess moisture from the indoor air every hour. This reduces the chance of mold build-up and helps to keep your living environment as healthy as possible.

Although this is a compact model, it is packed with excellent features. It boasts two-way air direction, two fan speeds and two cooling speeds as well as mechanical rotary controls. With its low power start up, you’ll be reducing the amount of energy you use, and since this model has a EER of 11.1, you’ll have lower energy bills while enjoying all the benefits of cooler air.

This air conditioner also has impressively quiet operation, so you won’t be disturbed whether you’re sleeping or watching TV. The antibacterial mesh filter can easily be accessed thanks to the slide-out function. It can be easily cleaned so harmful bacteria is removed from the air, reducing allergies and respiratory difficulties.

Even if you aren’t an expert in DIY, the pleated quick-mount kit is simple to fit yourself. The side panels are extending to enable the unit to fit perfectly into any window measuring between 23 and 36” in width and with a 13” minimum height. This is an air conditioner for horizontal sliding windows and vertical alike.


  • Easy-access antibacterial mesh filter
  • Quick-mount easy-install kit
  • Quiet operation
  • EER of 11.1 and low power start up
  • Fits in narrow windows
  • Dehumidifying function, removing 1.1 pints of moisture per hour


  • Only suitable for small spaces

  Bottom Line: If you only have a very small space to cool down or if you only have extremely narrow windows, this model is the one for you.


We’ve recommended five different models here, all of which are suitable for use in different types of spaces.

Whether you’re searching for a suitable unit for your compact dorm room or whether you need a model which is capable of cooling down a much larger space, we’ve suggested a casement window air conditioner that’s ideal for you.

window air conditioner unit

Although all the models that we’ve recommended are excellent choices, if we had to just recommend one it would have to be the EdgeStar Koldfront 12,000 BTU model.

Powerful enough to cool a room up to 500 square feet, this is a good choice for a larger home, and with its dehumidifying function, it can make your home a healthier and safer place to live, especially if you have allergies or breathing problems.

It's also incredibly energy efficient and extremely well priced! It's basically a great all-rounder that ticks every box.

Recommended: Learn how to clean window AC units in this guide.

Buyer’s Guide

If you’re choosing your first slider window air conditioner, you may not know how to begin making a final purchasing decision.

If so, read on and discover our helpful buyer’s guide. We’ll give you all the information you require to make the right choice for your home.

From the top things to consider before making your final choice to the best way to install your unit, we’ll tell you everything you need to know.

Things to Consider Before Buying

If this is the first time you've shopped for a window air conditioner for sliding windows then this section is well worth a read.

  • Area Coverage/Cooling Power – the top factor you need to bear in mind when choosing your first vertical window air condition is how much cooling power it can produce. This will be expressed in terms of BTUs (British Thermal Units). A unit with a higher BTU rating will be able to cool a bigger space. Therefore, if you have a particularly large room, you’ll be looking for a BTU rating of around 10,000.

    One further consideration relating to this is that if you’re going to install your unit in a space which is in full sunshine throughout the day or in a kitchen where it will be exposed to high cooking temperatures, you’ll need a higher BTU rated unit. When in doubt, always go with a higher BTU rating – if the rating is higher than you need, that won’t be a problem but if it’s too low your room won’t be cool enough and your purchase will be a waste of money.
  • Size – when you’re shopping for your window air conditioning unit, you’ll need to be aware of the maximum unit size which your window can allow. If you choose a unit which requires an opening height of 26” but your window only opens up to 24 inches, you won’t be able to install it. Always measure your window before you shop otherwise you could be disappointed.
  • Weight – A window air conditioner may be quite heavy. Usually, the higher the BTU rating, the heavier it will be. If you’re planning on installing the unit yourself, this is something you’ll need to keep in mind. There’s a pretty good chance you’ll struggle to install any air conditioning unit rated above 8000 BTUs on your own. If you don’t have anyone to help you, you might be better off choosing two lighter weight models instead of a single bigger one.
  • Location – where will you be locating your new air conditioner? The location of your unit is something which needs to be weighed up along with its weight and size. If, for example, you need to cool down a bedroom on the second storey, you’ll struggle to install and support a larger unit. Also, if you’re planning on installing the unit in a window which is in full sunlight all day long, you’ll need a higher rated unit.
  • Filtration – while some window air conditioners feature excellent filters, others don’t. You should look for a model which filters out allergens, bacteria and dust out of cooled air as otherwise these contaminants will be blown into the home causing allergic reactions and breathing problems. Whenever possible, choose a unit with a longer-lasting, reusable and rewashable filter as this will maximize its lifespan and improve the efficiency of your unit. 
  • Operation method – at one time, mechanical controls were the only option for window air conditioning units. Today, you can choose from a number of different controls. Some still feature mechanical controls, however others have digital readouts, remote controls or controls which allow you to select an option at the touch of a button.
efficient cooling
  • Efficiency – not only will you find each unit has a BTU rating, you’ll also find they have an EER rating too. The Energy Efficiency Ratio is a number representing the energy output compared to cooling power. If the EER number is higher, you’ll reduce your energy bills when compared to a model with a lower EER number. You’ll also reduce your carbon footprint – something which is very appealing in this day and age.
  • Air Speeds – you will want to have at least a couple of airflow speeds to choose from. In fact, you might want to have as many options as possible to choose from to give you all the flexibility you need in different weather conditions. This is particularly important during the night as the lower air speeds are quieter and so you won’t be disturbed as you sleep.
  • Programmable Or Timed Cycles – today’s air conditioning units often feature programmable and timed functions so you can make your model more efficient. You can set your unit to switch on before you arrive home so your room is already cool or set it to switch off after you go to bed.
  • Warranty – while sliding window air conditioners aren’t expensive, you should still look for a good warranty deal. When you’re investing in any air conditioning unit, you don’t want to make a purchasing error. Always choose a product with a warranty which covers as many parts as possible over the longest possible period of time.

Why Choose a Casement Window Air Conditioner?

Although casement window air conditioners can be ideal for many people, for some people they aren’t the right choice.

Here, we look at the pros and cons of choosing an air conditioner for sliding windows.


  • Lower priced than a central air conditioning system
  • Not permanently fixed into your window so you can remove it if necessary
  • Wide selection of options available so you can find one to suit your needs
  • Versatile – you can adjust the settings and controls to suit your needs and the current temperatures
  • Efficient – when you choose an Energy Star certified model you can be confident that you’ll save on energy and reduce your bills
  • Quiet running – the best sliding window air conditioning units are designed to operate quietly so they won’t disturb your sleep or leisure time
  • Drainage without added plumbing – these types of window air conditioning unit are designed to drain away water without needing to hire a contractor to fit new plumbing systems
  • Ideal for use in locations where summers are short


  • Aesthetically unappealing
  • May reduce the security of your home
  • Can be bulky and heavy to install, especially if you’re installing the unit alone
  • Hard to insulate and seal well
  • Sometimes, you’ll need to add exterior support

How To Install Your Casement Air Conditioner

The good news is, if you’re already familiar with your window opening size before you buy, you’ll find installation a breeze.

It’s always wise, however, to have another person to help you, especially if you’ve chosen a higher BTU model since these units can be heavy and bulky to handle.

  • You can install your air conditioner by following these steps:
  • Open the window widely
  • Put the air conditioner on the bottom of your window
  • Slide down the window until it has made contact with the unit
  • Using the shims, level the air conditioning unit. You’ll need to ensure that it is angled slightly towards the outside of your property to ensure proper drainage
  • Add installation hardware to support the unit then seal around your window. Sometimes, you’ll need to improvise when it comes to sealing in order to get an effective seal and eradicate air gaps
  • Add some additional support brackets outside to offer more support if you have a very heavy unit
  • Plug your new unit into a power outlet
  • Your cooling unit will now be ready to cool down your room

Visit this page for more detailed instructions.


There are lots of questions you may want answered when choosing a sliding window air conditioning unit.

Can I use an extension cord to power a window AC unit? 

The simple answer to this question is no.

Sliding window air conditioning units which are run using an extension cord will eventually build up heat in the cord. This could be a fire hazard.

You should choose a window for your air conditioner which is close enough to a power outlet so that you won’t need an extension cord.

Alternatively, hire an electrician who can install a new power outlet close enough to the unit.

Can I Get a Slightly Lower BTU unit To Save Money?

If you’re in doubt about what size unit to buy, you should always choose a higher rated model. If you opt for a lower BTU rated model, you’ll find that you’re wasting your money.

If you choose a model which is not the right size for your home you’ll waste money on your higher cooling bills and therefore it’ll just be false economy.

Is a Casement Window Air Conditioner Right For Me?

If you live in an area with warm weather all year round and are looking for a long-term ongoing solution to cooling, you might want to consider a central air conditioning system instead.

This will probably be a more practical solution in the long run. Alternatively, if you want an air conditioner which you can easily move between rooms, a portable model might be a better choice.

With so many different sliding window air conditioning units to choose from, it can be difficult to make the right decision.

However, if you follow our buying guide and our product recommendations, you can be sure that you’ll have all the information you require to find the best sliding window air conditioner to suit your individual needs.

Whether you’re looking for a model for a larger or smaller room, we have the perfect cooling solution for your home when a central air cooling system isn’t possible.

We hope you've found our guide useful. If you have any questions then be sure to leave a comment down below!

About the Author Jamie

I'm an English teacher and writer. I'm passionate about the environment and love the tiny house movement!

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