Best Sliding Window AC to Buy for Your Slider Windows in 2024

Best Sliding Window Air Contioner for Horizontal Sliding Windows

Sliding window air conditioners are perhaps the most pocket-friendly AC’s on the market. Not only are they cheap, but they also boast high energy efficiency. If these are exactly the features that you are looking for in an air conditioner, then our roundup of the best sliding window AC’s may interest you.

If you have horizontal slider or sliding window in your home, perhaps a sliding window air conditioner (also called casement air conditioner) is the perfect cooler you are looking for. This type of air conditioner is meant to be installed in a sliding window, thus the name.

Sliding Window Air Conditioner Comparison

How Do Sliding Window Air Conditioners Differ From Others?

To help you determine whether a sliding window AC indeed is the right choice for you, let’s talk about how this type of AC differs from others:

Sliding window vs central AC’s

Central AC UnitSliding window AC and window AC generally cost a fraction of central air conditioners. Expect to pay a few thousand dollars to buy and have a central AC set up, while a window unit will just cost you a few hundred dollars.

With that said, a ducted central AC will cool your entire house via ductwork, while a window AC will only cool the room it is installed in. On the other hand, window AC’s can be moved around to cool other rooms.

Sliding window vs ductless split AC’s

Ductless AC UnitDuctless split AC’s cool your entire home like central AC’s but without ducts. Instead, they use compact blower units situated throughout your house. Since each blower unit has a thermostat, you can set different temperatures in each room.

Ductless AC’s are much more expensive than sliding window units. In fact, they can sometimes be more expensive than central AC units.

Besides, compared to ductless systems, sliding window AC’s are much less functional. However, they are much cheaper and easier to set up. For single-room use, window AC’s can be ideal.

Sliding window vs portable AC’s

Best Portable Air Conditioner of 2015Compared to portable air conditioners, sliding window units are more efficient. This is because they exhaust hot air outdoors, while the typical portable AC exhausts hot air back inside. This downside doesn’t apply to double-hose portable AC’s, however.

Also, portable AC’s occupy floor space, which is a big downside in small rooms.

Sliding window vs through-the-wall AC’s

Through the Wall AC UnitThrough-the-wall AC’s are more costly to buy and install than window AC’s. Often, wall AC’s also require installation by a professional. Besides, they are permanent and cannot be relocated.

On the other hand, wall AC’s don’t limit your access to the window. Besides, wall AC’s can be tightly sealed, which ultimately increases their efficiency.

As you can see, sliding window AC’s have many advantages compared to other types of air conditioners. Hopefully, our little overview above gave you a good idea of what sliding window units can do and whether they are suitable for your needs.

7 Best Sliding Window Air Conditioners

LG LW8016ER 8,000BTU Air Conditioner – Editor’s Choice

 LG LW8016ER 8,000 BTU 115V Window-Mounted Remote Control Air Conditioner

If you are looking for an energy-efficient sliding window AC, then perhaps the LG LW8016ER is the right option for you. With an energy efficiency rating (EER) of 12.1, the LW8016ER is one of the most efficient units on our list.

Not only is this AC’s EER high, but it also has relatively low power consumption – just about 660 watts. As you’ll see next, this is quite low for a sliding window air conditioner of this capacity.

The LG LW8016ER air conditioner is not only energy-efficient but also powerful. With an output of 8,000 BTUs, this AC is suitable for spaces up to 340 square feet. This is very solid for a sliding window AC, but it’s certainly not the best.

For added flexibility and energy efficiency, LG LW8016ER has 3 cooling/fan speeds. On the low speed setting, this AC is fairly quiet as well – just about 52 dB. On the high setting, the noise level is 58 dB.

This unit also features an energy-saving mode for cases where you need just a tad of cooling. Besides, it has a 24-hour on/off timer. LW8016ER is quite compact as well for an 8,000BTU unit, so it should be a good option even for smaller windows.

Remarkably, the LW8016ER air conditioner also has a high dehumidifying capacity – up to 2.2 pints per hour. As you’ll see from our other reviews, this is quite a lot for a sliding window air conditioner.

What we also like about this sliding window AC is that LG includes a bunch of useful stuff with it – a remote control, an installation kit, installation instructions, and a mesh filter. The remote and installation kit are probably the nicest inclusions.

LG has also done a good job for durability – the LW8016ER air conditioner has gold fin anti-corrosion coating for increased longevity.

With that said, this unit isn’t free of downsides. Most notably, many users have complained about a rattling noise that seems to be due to the fan hitting something inside. This issue is fixable, but we feel that it shouldn’t have been there to begin with.


Volts 115 Volts
British Thermal Unit 8,000 BTU
Energy Efficiency Ratio 12.1
Noise Indoor dBA 58 High/52 Low
Max Room Coverage 340 sq.ft.
Weight 58 lbs
Remote Control Yes
Warranty 1 Year


  • Very energy-efficient.
  • 8,000BTU heat output.
  • 3 cooling settings & 24-hour timer.
  • High dehumidification capacity.
  • Quite compact for its cooling capacity.
  • Comes with a remote control.


  • May rattle out of the box.
Bottom Line
LG LW8016ER is highly efficient, functional, and quite compact. If you want to make good use of your space, then LW8016ER might be the best sliding window AC option for you.

Frigidaire FFRA051WAE 5,000BTU Window AC

 Frigidaire 5,000 BTU 115V Window-Mounted Mini-Compact Air Conditioner with Mechanical Controls

If you want a pocket-friendly unit, then consider the FFRA051WAE AC from Frigidaire. This sliding window AC isn’t as convenient as LG’s unit we’ve just reviewed, but it’s much cheaper. It’s quite energy-efficient too!

EER of 11 doesn’t seem too impressive after the 12.1 of the LG air conditioner. However, it’s still good enough, not to mention that the Frigidaire AC consumes less raw watts – just about 450!

If you want a quiet unit, then FFRA051WAE might be able to satisfy you as well. It produces 51.3 and 55 dB of noise on low and high settings respectively, which is pretty quiet.

In terms of cooling capacity, this is a small air conditioner – with 5,000BTU heat output, it is claimed to cool rooms up to 150 square feet. The dehumidification capacity is also on the lower side – 1.1 pints per hour.

But interestingly, this AC also has 2-way air direction control, which may make it a little more effective for your needs. Plus, it comes with a washable mesh filter.

On the other hand, FFRA051WAE has only 2 cooling/fan settings, and it also doesn’t have any timers or energy-saving modes. Add to that that it doesn’t come with any remotes, and you get a unit that’s not the most convenient out there.

With that said, it has one thing that the LG air conditioner didn’t have – it remembers its settings after power outages. The LG unit starts up in the energy-saving mode after shutdown, which can be annoying.


Volts 115 Volts
British Thermal Units 5,000 BTU
Energy Efficiency Ratio 11.0
Noise Indoor dBA 51.3 Low
Max Room Coverage 150 sq.ft.
Weight 41.5 lbs
Remote Control No
Warranty 1 Year


  • Best bang for the buck.
  • Rather energy-efficient.
  • Has a dehumidifier mode.
  • Very compact and quiet.


  • Comes with no remote controls.
  • Limited functionality.
Bottom Line
The FFRA051WAE AC from Frigidaire offers great value for the money. It’s not very functional and convenient, but it’s certainly much more pocket-friendly than other models on our list.

Friedrich CP08G10B 8,000BTU Air Conditioner

Friedrich Air Conditioning Co. CP08G10B Air Conditioner, 8000 Btu, White

The LG LW8016ER sliding window AC was functional, but CP08G10B from Friedrich may be even better for you. It has many of the features of the LG unit, and a few things more!

In terms of cooling capacity, the Friedrich AC is comparable with LG’s model. CP08G10B has an output of 8,000 BTU’s and covers up to about 350 square feet. Not only that, but it also has 3 cooling settings and a 24-hour timer for added cooling flexibility.

With that said, unlike the LG air conditioner, CP08G10B boasts automatic oscillating louvers to distribute cooled air left and right for better coverage.

In terms of power efficiency, it’s difficult to tell how good CP08G10B really is. This is because its EER ratings are inconsistent across different sources – Amazon says 11.2, the Friedrich website says 12.2, while this manual published on Amazon under Product Specification claims 10.8.

All these numbers are good, but it would be great if they were consistent. Depending on which number we go with, the wattage of this unit ranges from 655 to 740.

We also don’t know anything specific about the noise level – this spec is nowhere to be found. However, some buyers seem to have measured the noise to be at about 45-50 dB on the lowest speed. If true, this is very quiet indeed.

Apart from that, people have generally praised this model for quietness, so it might be a good option if that’s exactly what you are looking for.

Also, keep in mind that it does not have a dehumidifying ability, unlike the previous two units.

Finally, know that CP08G10B is quite pricey, though it could be worth it if you are looking for a low-noise sliding window AC.


Volts 115 Volts
British Thermal Units 8,000 BTU
Energy Efficiency Ratio 10.8
Noise Indoor dBA Not specified
Max Room Coverage 350 sq.ft.
Weight 64 lbs
Remote Control Yes
Warranty 1 Year for parts; 5 Years for Sealed Refrigeration System


  • 8,000BTU heat output.
  • Comes with a remote control.
  • 3 speeds & 24-hour timer.
  • Can perform side-to-side cooling.
  • Energy-efficient.


  • Inconsistent EER ratings across different sources.
  • No info on the noise level.
  • No dehumidification ability.
  • Pricey.
Bottom Line
Highly functional and seemingly quiet – these are the two key features of the Friedrich CP08G10B air conditioner. It’s a bit pricey and can’t work as a dehumidifier, but it’s a solid pick of a sliding window air conditioner nonetheless.

Koldfront CAC10000W 10,000BTU Air Conditioner

Koldfront CAC10000W 10000 BTU 115V Casement Air Conditioner with Dehumidifier and Remote Control

The CAC10000W sliding window AC from Koldfront is a good option in two cases – you need a high-power AC & dehumidifier and/or have horizontally sliding windows.

With 10,000 BTUs of heat output, CAC10000W is one of the two 10,000BTU units on our list. As such, it delivers a lot of cool air and can cover spaces from 400 to 450 square feet.

The dehumidification capacity of this model is also solid – 2.3 pints per hour.

However, in terms of energy efficiency, this isn’t the best model on our list, to be fair. With EER 10.4 and wattage of about 960, it’s quite a power-hungry unit. With that said, it has a low-power sleep mode along with 3 cooling/fan-only settings for added flexibility.

When it comes to windows, CAC10000W will work ideally with horizontal sliding windows. In fact, it’s designed to fit specifically this kind of window. The CAC10000W air conditioner will not fit vertical sliding windows due to its dimensions.

Speaking of dimensions, this is quite a bulky and heavy unit as well. This may imply some installation difficulties, but in the end, you are getting plenty of cooling capacity and great functionality.


Volts 115 Volts
British Thermal Units 10,000 BTU
Energy Efficiency Ratio 10.4
Noise Indoor dBA 59 High/55 Low
Max Room Coverage 450 sq.ft.
Weight 76.94 lbs
Remote Control Yes
Warranty 2 Years


  • 10,000 BTU’s output.
  • Covers up to 400-450 square feet.
  • High dehumidification capacity.
  • Has 3 fan settings, a timer, and a sleep mode.
  • Remote control included.


  • Only fits horizontally sliding windows.
  • Bulky and pretty heavy.
Bottom Line
The Koldfront CAC10000W sliding window AC is a nice option if you have a large space to cool. Not only that, but this thing has a high dehumidifying capacity, so it’s perhaps a good option for humid climates as well.

PerfectAire 10,000BTU Air Conditioner

PerfectAire 10,000 BTU Slider Air Conditioner Window A/C - Casement, 10000, Gray

This 10,000BTU air conditioner by PerfectAire is in many ways similar to Koldfront CAC10000W, but it has one key difference – it doesn’t have a dehumidification ability. If the climate in your area is dry, then PerfectAire’s air conditioner may be a better choice for you.

It’s also important to know that the PerfectAire AC is a little bit larger than the Koldfront unit, so be sure to check your window specs before choosing this model.

Other than that, we’d say that the two sliding window AC models are pretty much identical. Both have 10,000BTU heat output, cover up to 400-450 square feet, have 3 cooling/fan speeds, a timer feature, eco mode, and a few other things.

The similarity also applies to the energy efficiency, unfortunately – the PerfectAire AC again has a 10.4 EER and is rated at 961 watts.

But unlike Koldfront, PerfectAire lists the noise level of this air conditioner model, which is 56/58/61 dB on low/medium/high. This is pretty decent for its output but still noisier than the Koldfront.


Volts 115 Volts
British Thermal Units 10,000 BTU
Energy Efficiency Ratio 10.4
Noise Indoor dBA 61 High/56 Low
Max Room Coverage 450 sq.ft.
Weight 72 lbs
Remote Control Yes
Warranty 1 Year


  • 10,000 BTU’s.
  • 400-450 square feet coverage.
  • 3 speeds, eco mode, air direction controls, timer, and more.
  • Comes with a remote control.


  • Only for horizontal sliding windows.
  • Large and heavy.
  • Does not dehumidify.
Bottom Line
The PerfectAire sliding window AC is yet another good option for large spaces. Unlike the Koldfront unit, it can’t dehumidify your room. But if you don’t need to overpay for this feature, then PerfectAire’s model may be a good option for you.

Frigidaire FFRS0822S1 8,000BTU Air Conditioner

Frigidaire FFRS0822S1 8000 BTU Heavy-Duty Slider Casement Window Air Conditioner, Electronic Controls, Remote Control

The Frigidaire FFRS0822S1 sliding window AC is quite expensive for an 8,000BTU model, but it’s much more capable than all 8,000BTU units reviewed in our list so far.

Most notably, FFRS0822S1 has a very high dehumidification capacity – up to 3 pints per hour! With this in mind, it might be a great option for humid climates.

Not only that, but FFRS0822S1 is very quiet, with a noise level of just 48.4 dB on low and 55.1 dB on high.

In terms of energy-efficiency, the FFRS0822S1 air conditioner is pretty decent as well thanks to the EER of 10.8. However, its raw power consumption is higher than in previous 8,000 models – about 740 watts.

Another big difference from the other 8,000BTU air conditioners is that FFRS0822S1 is designed for horizontal sliding windows. If you have vertical sliding windows, then this model will not be for you.

But in terms of cooling capacity or general functionality, the Frigidaire sliding window AC isn’t much different from others – it again covers up to 350 square feet, as well as has 3 cooling/fan modes along with an energy-saving mode, a timer, and a few other goodies.


Volts 115 Volts
British Thermal Units 8,000 BTU
Energy Efficiency Ratio 10.8
Noise Indoor dBA 55.1 High/48.4 Low
Max Room Coverage 350 sq.ft.
Weight 66 lbs
Remote Control Yes
Warranty 1 Year for parts; 5 Years for Sealed Refrigeration System


  • 8,000BTU heat output.
  • Cools rooms up to 350 square feet.
  • Very high dehumidification capacity.
  • Rather energy-efficient.
  • Very low noise level.
  • 3 cooling modes, energy mode, timer, and more.
  • Remote control included.


  • Only for horizontal sliding windows.
  • High wattage.
  • Expensive.
Bottom Line
If you have horizontal sliding windows and want a quiet and functional air conditioner for them, then FFRS0822S1 may be the way to go. It’s also a great option for humid areas. FFRS0822S1 is quite expensive, but it’s arguably the best 8,000BTU model on our list.

Frigidaire FFRA0511U1 5,000BTU Air Conditioner

 FRIGIDAIRE FFRA0511U1 Air Conditioner, 5,000 BTU, White

Finally, we have the FFRA0511U1 AC from Frigidaire. This model is very similar to the Frigidaire FFRA051WAE we reviewed earlier, but there are a few important differences to keep in mind.

First up, this unit has a higher dehumidification capacity – 1.6 pints/hour vs 1.1 pints/hour in the other Frigidaire unit. Secondly, with an EER of 11.2, this AC is just a tad more energy-efficient and consumes less power. And finally, it has a sleeker design and is slightly more expensive than the previous model.

Other than that, the two Frigidaire ACs are very similar. More precisely, they are similarly low-functionality – unlike most other models on our list, they only have 2 cooling/fan speeds, have no energy-saving modes or timers, and come with no remote controls.

With that said, the FFRA0511U1 AC is also very compact, so it’s a good pick for smaller windows. Besides, it’s just as quiet as the other 5,000BTU Frigidaire AC – its noise level is about 51 dB on low and 55 dB on high.


Volts 115 Volts
British Thermal Units 5,000 BTU
Energy Efficiency Ratio 11.2
Noise Indoor dBA 55 High/51 Low
Max Room Coverage 150 sq.ft.
Weight 47 lbs
Remote Control No
Warranty 1 Year for parts; 5 Years for Sealed Refrigeration System


  • Energy-efficient.
  • Very good dehumidification capacity.
  • Very compact and quiet.


  • No remote controls included.
  • Limited functionality.
Bottom Line
Compared to the previous 5,000BTU Frigidaire air conditioner, FFRA0511U1 is a better option if you want a quiet sliding window AC. Aside from that, this AC is very compact, efficient, and easy to install.

How to Choose the Best Sliding Window Air Conditioner

Horizontal Slider Window
Check your window specs first before getting the right sliding window air conditioner.

Now, to help you pick the best window AC for your needs, let’s talk about the most important things to pay attention to while shopping for one. We won’t be covering general AC stuff – instead, we’ll focus more on the features that matter in sliding window air conditioners.

Horizontal vs vertical units

Horizontal Slider Window for Sliding Window AC
Horizontal Slider Window
Vertical Slider Window for Sliding Window AC
Vertical Slider Window (Single-Hung)

To cover gaps in the window after installation, window air conditioners have extending panels. In AC’s designed for vertical sliding windows, the panels extend to the sides of the unit. With models designed for horizontal windows, the panels extend upward.

With this in mind, when shopping for a sliding window AC, check the type of your window first. If you have a horizontal sliding window, buy an AC that’s specifically designed for such windows.

Usually, manufacturers clearly indicate what kind of windows their models are intended for. You may also determine this by having a look at the dimensions of the unit.

Tall air conditioners are typically designed for horizontally sliding windows because they cannot fit under vertical sashes. Short units are usually designed for vertical sliding windows.

Also, know that AC’s intended for vertical sliding windows may be installed in horizontal windows, but horizontal units cannot be installed in vertical sliding windows due to size constraints. However, a unit designed for vertical windows wouldn’t be ideal for horizontal sliding windows.

This is because there would be a gap above the window that the AC is not designed to cover. To seal the gap, you would need to do some DIY. This isn’t ideal because it’s difficult to achieve an airtight seal, but it is possible.


Check out how much space the desired window AC is designed to cover. Typically, manufacturers indicate the maximum area that can be cooled by the unit in square feet.

You may also determine the maximum area that an AC can cool based on its BTUs. According to Consumer Reports, a good rule of thumb is that window air conditioners need 20 BTUs for each square foot of space.

Apart from that, Energy Star recommends the following adjustments to the AC capacity based on the room’s existing conditions:

  • Reduce BTUs by 10% if the room is heavily shaded.
  • Increase BTUs by 10% if the room is very sunny.
  • Add 600 BTUs per person if the room is often occupied by two or more people.
  • Add 4,000 BTUs for an AC that will be used in the kitchen.

For quick general reference, check out the table below.

150 sq.ft. 5,000 BTU
250 sq.ft. 6,000 BTU
350 sq.ft. 8,000 BTU
450 sq.ft. 10,000 BTU
550 sq.ft. 12,000 BTU
700 sq.ft. 15,000 BTU
1,000 sq.ft. 18,000 BTU
1,500 sq.ft. 25,000 BTU
2,000 sq.ft. 28,000 BTU

Energy efficiency

The energy efficiency of window air conditioners is measured by EER (Energy Efficiency Ratio). It is calculated by dividing the unit’s BTUs by its wattage.

The higher the EER, the more energy-efficient the air conditioner is, which is what you want to have. However, aside from paying attention to EER, consider the raw wattage of the unit as well.

High EER means that an AC can provide you with more cool air per consumed watt. But a high-EER AC may still have high raw wattage and be expensive to run. So be sure to check the wattage of the desired AC as well. If not provided, just divide its BTUs by the provided EER.

Manufacturers usually provide annual cost estimates with their window air conditioners. You may check those as well to determine how costly the unit will be to run.

Window size

Make sure to check the window sizes supported by the desired sliding window air conditioner. More precisely, check the minimum/maximum width & height of the window that is required by the unit. Your window should meet those requirements.

Noise level

If you care about the noise level as well, then pay attention to it while shopping for a sliding window air conditioner.

Manufacturers usually provide noise levels for each of the cooling settings that the AC supports, so be sure to check them out. But keep in mind that more powerful models will be noisier.


Finally, check out the functionality of the desired unit. Among the things that you may want to have in your sliding window AC are:

  • The number of cooling settings. The more, the better because you’ll have more control over power consumption, noise, and cooling.
  • Fan-only mode where cooling is achieved only via the built-in fan.
  • Sleep & energy-saving modes.
  • Timers.
  • Louver oscillation.

Also, you may want your AC unit to come with a remote control for convenience. Not every window air conditioner comes with one, so make sure to check the product description if you want a remote.

How to Install a Sliding Window AC Yourself

If you are going to install a sliding window air conditioner yourself, then here’s how you should generally do it:

  1. Place the air conditioner on a flat surface.
  2. Install all top/side rails that come with the unit. You may need to consult the manual to know how to properly install the rails.
  3. Mount side/top filler panels to the air conditioner. When installed, the flanges securing the panels in place should be facing the room.
  4. Know that the rails and panels are offset to ensure a proper pitch for easy water drainage.
  5. Cut seal foam into proper length and stick it to the lower part of the window frame. If you have a unit designed for horizontal sliding windows, then you generally need to stick seal foam to the side of the frame.
  6. If you have storm windows, then you will either have to remove them or add a piece of wood to the windowsill to ensure that the unit maintains proper pitch.
  7. Carefully place the air conditioner into the window opening. The bottom of the air conditioner should be against the sill.
  8. Close the window behind the top/side rail of the unit. The rail should thus stay inside.
  9. Extend the side/top panels into the window frame.
  10. If your unit comes with a frame lock, install it between the panels’ frame extensions and the windowsill.
  11. Drive screws through the frame lock into the sill. If you have vinyl windows, then you should drive the screws into the sash.
  12. Secure the lower sash in place with right angle sash locks. These should be included with your AC.
  13. Cut foam seal and insert it between the upper and lower/left and right sashes of the window.

Safety and Precautions

Safety FirstYour sliding window AC should come with installation instructions. These should provide you with clear directions on how to install your specific air conditioner model. You may address a professional if your instructions are unclear or if you don’t want to deal with the setup yourself.

To stay safe when installing your sliding window AC, follow these tips:

  • Don’t install the AC alone.
  • Carefully read the included manual before setup. Pay special attention to danger and safety notices.
  • Observe all local electrical codes.
  • Make sure that the location where the AC will be installed is strong enough to withstand the unit’s weight.
  • Only use screws and hardware provided by the AC manufacturer.

Issues with Sliding Window AC’s To Know About

Although sliding window AC’s have many advantages over other AC types, they have some problems that you may need to deal with as well:

  • Weight hazard. Window AC’s are a weight hazard, and if installed improperly, they could fall out of your window. Not only may this cause injuries in bystanders, but you may also face legal charges.
  • Weight distribution. Sliding window air conditioners can get pretty heavy and thus need to have proper support beneath them. This especially is a problem with vinyl windows. You may need to reinforce your window frame so that it can support your unit.
  • Air leaks. To run as efficiently as possible, your window AC should be in an insulated room. This means that you should deal with each and every crack in the room, especially the window where the unit is installed.
  • The water from AC’s has to go somewhere. In apartment buildings, the water will be dripping right down onto the head of your neighbor. This may create some disagreements with those who live below you.

Should You Really Get A Sliding Window AC?

Sliding window AC’s sure have a few great benefits, but would such an AC be the best option for you?

Well, we think that a sliding window AC is a reasonable choice if:

  • You have a limited budget.
  • Swamp coolers are not enough for your cooling level.
  • You need cooling in just one room at a time.
  • If you have a horizontal slider window.
  • You don’t want to dedicate any floor space to your AC, which you would need to do with a portable unit.

If these check for you, then perhaps a sliding window AC would be the best kind of AC for you. Otherwise, do more research to find out which air conditioner style would truly be the best option for your needs.

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