Top 8 Casement/Vertical Window Air Conditioners in 2021

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If you have casement windows, then your only AC option is a casement or slider window air conditioner designed for vertical openings. Many homeowners call them sliding window air conditioners.

Very few brands make casement window ACs, but we rounded up eight vertical window air conditioners from four different manufacturers, and one of them should meet your needs.

The Best Casement Window Air Conditioners

Here’s a summary table of the six best sliding window ACs. Their reviews follow.

      Image                    Product

Frigidaire FFRS0822S1

  • 8,000 BTUs, 250-350 sq. ft. 
  • 23.5 x 14.2 x 20.2 inches
  • Remote, 24H timer

Koldfront CAC8000W

  • 8,000 BTUs, 250-350 sq. ft. 
  • 20.8 x 14.5 x 23.5 inches
  • Energy star, Remote

Arctic King 8,000 BTU 110-Volt 

  • 8000 BTUs, 250-350 sq. ft. 
  • 21.3 X 14.6 X 20.9 Inches
  • Energy star, Remote

PerfectAire 3PASC10000

  • 10,000 BTUs, 350-450 sq. ft. 
  • 23.5 x 14.5 x 20.5 inches
  • Remote, 5 modes

Frigidaire FFRS1022R1

  • 10,000 BTUs, 350-450 sq. ft. 
  • 23.5 x 14.5 x 20.2 inches
  • Remote, 24H timer

Arctic King 10,000 BTU

  • 10,000 BTUs, 350-450 sq. ft. 
  • 23.5 X 14.6 X 20.9 inches
  • Remote, 5 modes
Keystone 10,000 BTU

Keystone 10,000 BTU

  • 10,000 BTU, 350-450 sq. ft.
  • 23.5 x 20.87 x 14.57 inches
  • Popular sliding window AC
Koldfront CAC10000W

Koldfront CAC10000W

  • 10,000 BTU, 350-450 sq. ft.
  • 23.5 x 14.5 x 20.87 inches
  • Remote plus Dehumidifier

Next, we review each of these vertical window air conditioners before a brief buying guide designed to help you choose the best unit for your AC purposes. But first, let’s clear up the confusion about just what a casement window AC is - AKA - sliding window air conditioner.

Clearing Up Confusing Terminology

These units are called by many names.

Casement and gliding/sliding window air conditioners refer to the window types that they fit into.

Vertical window air conditioners are used because they tend to be taller than they are wide. However, some also call them horizontal window air conditioners because the windows they fit into open horizontally rather than vertically, unlike a double-hung window.

Installation is similar, but instead of “wings” or material that spreads out side-to-side, the kits come with material to fill the gap between the top of the casement AC / vertical window AC and the top of the window. There is more on sliding window air conditioner installment in the FAQ guide following the full Reviews below.

Pro Tip: These units will not fit into most single-hung and double-hung windows. If you happen to be here but are looking for a standard window AC, the type that fits into a window with a vertically opening sash (double-hung/single-hung), then see our many guides to standard window air conditioners available by hovering over the Window AC tab at the top of the page.

Another option is to start with our Complete Window Air Conditioner Review and Buying Guide.

Sliding Window Air Conditioner Reviews

There are three 8,000 BTU casement window air conditioners and three 10,000 BTU window units. Those are the only sizes available in casement window ACs.

#1 Frigidaire FFRS0822S1 8000 BTU AC

This Frigidaire sliding window AC removes 8K BTUs of heat per hour, so does a good job cooling space up to 350 square feet.

It has a good group of features. Here are the key points to consider.

  • Width: 14.2 inches
  • Features: 24-hour timer, full-function remote, Sleep mode, Energy Saver mode, 3-speed fan.
  • Pros: Narrow window AC, has all the features needed for convenience and making the room comfortable. Positive ratings are 73% to 77%.
  • Cons: Nothing major. Energy Saver mode reduces cooling, but that should be expected. You might want to use plexiglass instead of the foam supplied to fill the gap between the top of the AC and the top of your window opening. Negative ratings are about 12% to 14%. Many of them have to do with the unit being dented upon arrival, something Frigidaire seems to have addressed with better packaging.

#2 Koldfront CAC8000W 8000 BTU 115V AC

This is an 8,000 BTU Koldfront casement window air conditioner with basic features only. On the positive side, this is an Energy Star casement AC that delivers lower operating costs.

Compared with the Frigidaire model, it is an affordable sliding window air conditioner.

  • Width: 14.2 inches
  • Features: Full-function remote, Energy Saver mode, 3-speed fan.
  • Pros: Energy Star. Compact window AC.  Affordable. Positive ratings are 74% to 76%.
  • Cons: Doesn’t have a timer.

#3 Arctic King 8,000 BTU Slide Casement Window AC

This Arctic King sliding window AC delivers 8K BTUs of cooling. It has an auto-restart mode, so that if the unit is running when there is a power outage, it will turn back on at the same thermostat setting when power is restored.

When you choose Follow Me mode, the AC will use the temperature where you and the remote are to determine how much cooling it puts out.

  • Width: 14.6 inches
  • Features: Full-function remote, auto-restart, single-speed fan, Sleep mode.
  • Pros: Energy Star. Compact window AC.  Positive ratings are about 80%.
  • Cons: Doesn’t have a timer. Single-speed fan doesn’t allow for quieter, gentler cooling. Weighs more than most slider window air conditioners and is slightly wider than other 8K BTU models.

#4 PerfectAire 3PASC10000 Window AC

This 10,000 BTU casement window AC has a lot of features that improve indoor comfort. The remote includes a separate thermostat. This unit also has Follow Me mode (see the Koldfront AC description).

AC mode lowers the temperature. Fan mode moves the air and creates a little white noise.

Dry mode dehumidifies the room without cooling. It’s an ideal mode for cool, damp spring and fall days when you want to get rid of the clammy feeling. You can also choose Auto mode, which selects the best mode to meet the thermostat requirement based on indoor climate conditions.

  • Width: 14.5 inches
  • Features: Remote, auto-restart, Cool/Fan/Dry/Auto modes, Sleep Mode too, programmable timer.
  • Pros: This PerfectAire casement window AC is more compact than some 8,000 BTU models. It has the widest range of features available and is light. 67% to 70% of the reviews are positive.
  • Cons: Louder than most other casement window units. That is the biggest complaint, so this unit might not be the right choice for bedroom installation. About 15% of the reviews are critical.

#5 Frigidaire FFRS1022R1 10000 BTU AC

This is from the same Frigidaire series as the unit above but in the 10,000 BTU slider window air conditioner size.

The Frigidaire 10,000 BTU window AC for horizontal windows has a full range of convenience and comfort features including a 24-hour timer that allows you to program when the unit runs.

The timer allows you to leave home with the unit off, and if programmed, it will come on and cool your space before you arrive. That’s the best way to reduce energy use and still have a comfortable room or apartment.

  • Width: 14.5 inches
  • Features: Remote, Programmable timer, 3-speed fan with Auto setting, Cool, Fan Only and Energy Saver modes.
  • Pros: Good climate control features, affordable cost for a 10K sliding window air conditioner. 77% to 80% of reviews are positive.
  • Cons: About 15% of the reviews are critical. The biggest concern is that it might be damaged on deliver. You can return it to Amazon for replacement or refund, but that’s an inconvenience.

#6 Arctic King 10,000 BTU AC

This is the 10K BTU version of the Arctic King casement window air conditioner listed above. It operates on a standard 110-volt plug, so you won’t need to install a 220V outlet.

Like many window air conditioners, this one has a “slinger-up” ring that splashes water removed by the AC onto the outdoor coil/radiator for faster, more efficient cooling.

  • Width: 14.6 inches
  • Features: Remote, Follow Me mode on remote, multiple fan speeds, 24H timer, Auto/Cool/Dry/Fan/Sleep modes, dirty filter notification, Exhaust feature to remove polluted indoor air.
  • Pros: Good climate control features, affordable cost for a 10K sliding window air conditioner. 77% to 80% of reviews are positive. 70% of the reviews are positive.
  • Cons: Heavier than other 10K BTU gliding window models. Less than 20% of the ratings are critical.

#7 Keystone 10,000 BTU Slider/Casement Window AC

Keystone is a brand that “flies under the radar” sometimes, but it is growing in popularity. The manufacturer is known for quality appliances at affordable costs, and this one is no different.

And as noted in the review below, it comes with excellent consumer ratings. It’s a newer model too, so if you want the latest in sliding window AC technology, it is worth a look. 

Keystone 10,000 BTU
  • Width: 14.57 inches
  • Features: Remote, 3 fan speeds, Auto/Cool/Dry/Fan/Sleep modes, dirty filter notification, 
  • Pros: About 90% of users give this unit a positive rating, and that makes it one of the top rated sliding window air conditioners on the market. Features are about what you’d expect from good window ACs.
  • Cons: A few of the units arrive damaged from shipping, though still in working order. You have the option of returning it or using it as-is. This, of course, isn’t the fault of Keystone, but typically the shipping company. And by the way, this can be true of absolutely and product, especially heavy ones, shipped from any seller.

#8 Koldfront CAC10000W 10000 BTU 115V Casement Air Conditioner

The dehumidifier on this Koldfront window AC for sliding windows is useful on cool, damp days. It doesn’t cool off the room, but it does take the dampness/humidity out of the air, so the room doesn’t feel “clammy” anymore. 

That’s the value of ACs with dehumidifier mode - which is often referred to as “dry mode.” They are worth considering in climates with cool, damp spring and fall weather (or winter, if your climate is generally mild). 

Koldfront CAC10000W
  • Width: 14.5 inches
  • Features: Digital AC display for accurate temperature setting. Dehumidifier. 3 fans speeds for versatile cooling. Sleep mode included plus energy saver mode to lower energy costs. The remote has a 16-foot range, good enough for most rooms this sliding window AC is suitable for.
  • Pros: More than 90% of reviews from verified users are good or excellent. It has all the features you’d expect in a quality vertical window AC. Plus, it is a fairly new model, so has all the latest technology and efficiency features. 
  • Cons: While the energy saver mode reduces energy use - and therefore energy costs - you might find that it won’t adequately cool the space in very warm, humid weather. 

What Size is Right?

You only have two options, unfortunately. Here’s how to choose, and it’s more than just the square footage of the room or zone.

As a general starting point:

  • 8,000 BTU AC is designed for 300-350 square feet
  • 10,000 BTU AC is ideal for 400-450 square feet

The Department of Energy gives further guidance on sizing a casement window air conditioner.

  • Shady: If the room/zone is shaded, you can get by with the designated size or possibly a smaller AC than recommended.
  • Sunny: If it’s sunny, you should choose a larger size.
  • Crowded: If the room usually has 2 or more people in it, you might want the larger size.
  • Cooking: If the slider window air conditioner will cool a kitchen, you definitely should choose the larger size.

Here are a couple examples to show how to size your window AC.

20x16 bedroom = 320 square feet. If the room is shaded, then the 8K unit is perfect. If it is sunny and warms up in the afternoon heat, then choose a 10K unit.

16x12 kitchen = 192 square feet. Normally, that amount of space would require a 6,000 BTU window air conditioner. However, since the stove or range top might be frequently in use, you should consider an 8,000 BTU unit. If the kitchen is 300 square feet or more, then the 10K unit would be a better option.

Choosing the Best Sliding Window AC

Horizontal window ACs in our list – in any list – come in basic and affordable models with some features and top-of-the-line models with all the features.

We chose a selection, but they have one thing in common – good dependability and quality.

Which type is best for you – Basic, Better or Best?

Basic casement window units

A unit with basic features will make you happy if you want to spend less and wouldn’t use a timer much. For example:

  • No hurry: You don’t mind waiting for the AC to cool off the room when you get home from work
  • You’re home anyway: The AC is in a bedroom and you are usually at home at least an hour before you go to bed, so you can turn it on without a timer
  • Basic works for you: You want the space cooled and don’t care about advanced modes like Exhaust, Fan-only, Sleep Mode or Energy Saver Mode. Tip – A lot of consumers don’t like Sleep and Energy Saver modes because the ACs don’t run as cool during those modes. To these people, those modes could be renamed “warm” modes, and that’s not why they bought the AC to begin with.

Basic casement window models: Koldfront CAC8000W

Better casement window units

Window air conditioners in this range have some, but not all, the features available.

  • Comfort: Various modes allow you to choose the right comfort setting for the indoor climate conditions such as Cool/Dry/Fan.
  • Convenience: Timers allow you to program the AC to come on. You don’t have to leave it running, but you will still have cool air when you want it.

Better casement window models: Frigidaire FFRS0822S1 and Frigidaire FFRS1022R1

Better casement window units

These units have all the features of the “better” models plus a few more bells and whistles. For example:

  • Follow Me thermostats are innovative. If you’re across the room from the AC, then it will choose a high fan speed to push cool air your way. If you’re close to the AC, it might choose a slightly higher temperature and a lower fan speed to optimize your comfort without making you chilly.
  • Dry mode – dehumidification only for cool, damp days is another feature not found on most slider window air conditioners.

Best casement window AC models: Arctic King 8,000, Arctic King 10,000 and PerfectAire 3PASC10000

Installing your Sliding Window Air Conditioner

You probably won’t be surprised to know that Pick HVAC has completed a Window AC Installation Guide that covers installation of all types including vertical window / casement window ACs.

These units are heavy, so it might be helpful to assist the help of a “second set of hands” to help you raise the AC into place and hold it when the time comes. 

The basics are to make sure all installation supplies are included in the box. Read the instructions to gain an overview of sliding window AC installation. 

Then, attach any of the parts directly to the AC that are required. Measure to know how big the window panel must be, and cut it to fit. The window panel is the material that fits between the top of the AC and the window frame above it. 

Pro tip: Do this before you get too deep into the installation process, because if your window is very tall, you might need extra material - not included with the AC - to adequately fill the gap. 

Once the AC is installed and secured, use weatherstripping to stop potential air gaps that will harm the unit’s efficiency. 

Is professional installation an option? 

Yes it is. When you order a sliding window AC from Amazon, some models do offer a pro installation option. Choose that, and follow the prompts to set up pro window AC installation. 

How much does shipping cost?

When you buy a vertical window AC from Amazon and other top online sellers, shipping is usually free. 

Are buyer protection plans available on sliding window ACs?

Yes. Most cost between $55 and $90 depending on the initial cost of the purchase and whether the protection plan. 

Are buyer protection plans worth it? 

Well, put it this way - they are offered because Amazon and the third-party company that provides them make money off them. They’re worth it - to the seller, but not as often to the buyer. 

If you’re prone to breaking things, then it might be worth it. If you’re a careful homeowner, then we do not recommend you spend the money on a buyer protection plan. 

One other thing to consider is that they do cover mechanical failure after the end of the unit’s standard warranty coverage. In other words, if the AC is covered for 1 year and you have a 3 year protection plan, the plan will cover mechanical issues for 2 years after the warranty ends. 

Are portable air conditioners the same thing? Will they fit in a window?

No and no. We see other sites advertising portable air conditioners as “vertical window air conditioners,” and this is just false advertising. See our Portable Window Air Conditioner guide for full details on just what a portable AC is and whether it might be right for your air conditioning needs. 


Does LG make a vertical window AC?

Does Haier make a casement window AC?

Does GE make a vertical window AC?

We get this question in lots of similar versions, as you can see.

LG used to make one, but it was discontinued.

Haier does not and apparently never did. The same is true for GE.

Why are there so few options in vertical window ACs?

It is a little strange, since casement windows are popular. But single-hung and double-hung windows are still more common, so “standard” orientation window air conditioners sell far better.

Is PerfectAire a good window air conditioner brand? I’ve never heard of it.

Yes, it is. PerfectAire doesn’t make as many air conditioners as Frigidaire, GE, LG and other brands we’ve all heard of. But what it makes is good quality. The unit in our list above gets about 85% high ratings on most consumer review sites including Amazon.

We value your trust in us too much to suggest inferior products to our readers!

Can a vertical AC be installed in a wall?

Yes, but most do not come with sleeves that make it easy to slide them in and out of position.

You would need to build a frame for it using framing timbers like 2x4s or 1x6s. Add caulking and/or weatherstripping around it to reduce air leakage and boost comfort and efficiency.

Can I make a vertical window AC out of a regular one?

Can a window AC be placed on its side?

No. The AC would run for a short time, but mechanical failure would be inevitable. This is because the lubricant in the compressor will only do its job when the unit is properly positioned. Without the benefit of the oil, the compressor would soon seize up.

Did you know? If you order a vertical AC from Amazon or elsewhere, it might arrive on its side. Delivery people aren’t used to handling vertical ACs.

If this happens, set the AC upright, and do not turn it on for at least 8 hours. This will allow the lubricant to flow back to where it should be.

Why won’t my window AC cool the room?

We’ve fully addressed this issue in an FAQ guide called Why is My Window AC Not Cooling? But here are some of the more common issues. 

First, it might be too small. See the Window AC Sizing Guide above or follow our recommendations to ensure your AC is big enough for the space. Secondly, make sure it is in Cool mode because it won’t air condition (cool) the room if it is in Fan mode or Dehumidifier mode. 

Thirdly, it could be that you waited too long to turn it on. If the window faces the sun, and it is really hot and sunny out, the room could easily exceed 90F. In that case, it will take the AC quite a while to cool the room. If you know it is going to be very hot and sunny - especially facing the AC - turn on the unit before the room gets super-heated. 

Finally, of course, the unit could be broken. If you’ve checked everything else, and your window AC isn’t cooling the room, then it has probably leaked its refrigerant, the fan isn’t working or the compressor has failed. It could be a thermostat issue too, meaning the unit “thinks” the room is as cool as you want it and isn’t signalling the compressor to come on.

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