If your house doesn't have central AC, you might want to consider adding a window unit. There's a wide variety of air conditioners for sliding windows available on the market today, and they do an excellent job of cooling single rooms. Whether you're looking to keep your bedroom or living space cool, you shouldn't have a problem finding a model that'll work for you.
It's easy to be overwhelmed if this is your first window air conditioner purchase. After all there's a lot to consider. Purchasing a unit too small or with the wrong features can leave you suffering when the temperatures begin to rise. This article will provide you with the information you need to know to buy a air conditioner for sliding windows, and we'll even provide you with a few of our favorite models to help you begin shopping.
Window air conditioners are designed to be installed in a window and can cool up to two rooms. Although most commonly installed in windows where they can be removed during the off-season, some models can also be permanently built into a wall opening.
Since there are so many different window styles and dimensions, window AC units come in a variety of sizes. There are vertical sliding window air conditioners that are tall and skinny; and horizontal models that are shorter and wide.
The style you purchase will largely depend upon the type of windows you have in your home.
Elements of a Window AC Unit
A window air conditioner is a self-contained cooling system which includes the following parts:
- Evaporator coil
- Condenser coil
- Expansion valve
- Two motorized fans
- Air Filter
- Thermostat (manual or digital)
- Control panel
How a Window Air Conditioner Works
Window air conditioners work the same way all other AC units operate. The compressor compresses the refrigerate and pumps it into the condenser coils.
The condenser coils dissipates the heat as liquid travels through the coils. As the refrigerate leaves the condenser coils it goes to the evaporator coils in the front of the unit.
When the refrigerate liquid enters the evaporator coils, it expands to a gas and makes the coils cold. The refrigerate then returns to the compressor to start the cycle again.
The following video shows how a window air conditioner works.
Watch the Video
Buying a window AC unit can be a daunting task, especially if this is the first one you've purchased. This guide will help give you the information you need to make an informed decision.
Types of Window AC Units
There are several types of window AC units available. The main difference is the dimensions. Since there are different types of windows it makes sense that there will be different window AC units designed to fit each unique size.
The two main types are:
- Vertical Window Air Conditioners
- Horizontal Window Air Conditioners.
Vertical Window Air Conditioners
Vertical window AC units are becoming more popular since new home construction tends to install windows that open up-and-down instead of left-to-right.
With their tall and narrow build, a vertical sliding window air conditioner uses gravity to help keep it in place. The unit sits on the bottom window sill and the lower window fits snuggly on top to help give it a stable fit.
That's not to say that a vertical window air conditioner can't be installed in a horizontal sliding window. You'll just need to make sure the unit has exterior support, such as an installation bracket to prevent it from tipping outwards.
Horizontal Window Air Conditioners
Households that have windows that open from left-to-right often choose a horizontal window AC unit. These types of windows are opened by pushing one panel sideways so that it covers the stationary glass panel.
Horizontal window AC units are wider than they are tall and require an installation bracket in order to keep them in place since the majority of the weight of the unit is outside.
There is, however, a new hybrid of horizontal window air conditioners that can be used with vertical sliding windows. The Midea U Inverter only minimally blocks the window as its designed for the window to sit within the unit.
And, the SoleusAir Saddle straddles the window frame in a way that the window is not blocked and can still be used. Although, designed for vertical windows, it can also be used with horizontal windows, as shown in this video.
Both of these designs are among our favorite sliding window air conditioners so you can read more about them here.
Both vertical and horizontal window AC units are popular choices, and you'll have many different models to choose between. Another option is to purchase a portable AC unit that can be installed near a window, but not within a window.
Purchasing an AC unit that fits your window is a critical point. With so many different model sizes available, you shouldn't have a problem finding one that meets your needs. But you do need to pay attention or you may have a new air conditioner that simply won't fit!
Provided your window air conditioner fits within the window frame, you can pick up inexpensive insulation panels to fill in any additional width and height space. Although, most units come with at least some supplies to make a snug fit.
Cooling capacity refers to the amount of area the air conditioner unit can effectively cool. When it comes to purchasing an AC unit, this is extremely important, and not a step you want to skip.
British Thermal Units (BTUs) are used to measure an air conditioners cooling capacity. The higher the BTU hourly rating, the larger the room the unit will be able to cover.
Purchasing a window air conditioner that doesn't have the BTU power to cover the intended space will waste energy and place unnecessary wear-and-tear on the unit. This is because it will need to work harder than it should in order to cool the room.
Purchasing a unit that is too large will cool the room, but will leave your room feeling damp. This is because it won't be able to remove the humidity from the air as efficiently as a unit that is properly sized for your room.
How to Properly Size a Window AC Unit
In order to determine the cooling capacity necessary, you'll need to know the square footage of your room. This video will show you how.
Watch the Video
Now, armed the room's square footage, you can find the BTU measurement that'll provide the right cooling capacity to cover the room's space. Use the chart below:
BTU Sizing Chart
Room Square Footage
100 to 150
150 to 250
250 to 300
300 to 350
350 to 400
400 to 450
450 to 550
550 to 700
Window AC Sizing Tips
- If you're between sizes, it's always best to purchase the larger model.
- The amount of people in the space will impact the AC's cooling capacity. A good rule of thumb: If you have more than 2 people in a room, add 600 BTUs for each additional person.
- Ceilings higher than 8-feet will impact the cooling capacity performance. Increase your BTU requirements by 20% to account for the added space.
Purchasing a sliding window air conditioner that's energy efficient can help reduce your energy expenses. It might surprise you that manufacturers don't make this a standard feature, but they don't. Here are a few things to consider:
Energy Star Certified
If you purchase an Energy Star window AC unit, you can expect that it'll use at least 10% less energy than models that didn't earn the certification.
One of the advantages of Energy Star units is they frequently provide better temperature control features, making it easier to manage energy consumption. Digital thermostats, automatic cooling modes, multiple speeds, and programmable timers are all excellent features for both comfort and energy efficiency.
Energy Efficiency Ratio
Another efficiency indicator is the Energy Efficiency Ratio, also known as EER. The EER measurement calculates how many BTUs a window air conditioner consumes for a single watt of power.
When comparing models, look for a high EER measurement because the unit will run more efficiently.
The US Department of Energy recommends window AC units have a EER rating of at least 10.0. As a general rule, you can expect a 1% drop in electricity usage for every 0.1 EER increase.
Before purchasing a window AC unit you'll want to make sure your household electrical system can support the model you choose.
- A window air conditioner with a 15,000 BTU cooling capacity (or below) will typically operate on a 115 or 125-volt circuit.
- A window air conditioner with a cooling capacity above 15,000 BTU will typically require a 220-volt circuit.
Most living spaces such as bedrooms and living rooms has electrical outlets that can handle 115 to 125-volt units. However, if you require a unit that runs on a 220-volt circuit, you'll most likely need to hire a electrician.
Always review the voltage, amps and watts that are listed for the unit and make sure that your electrical outlet can accommodate the plug. In addition, make sure that the AC unit electrical cord will reach your electrical outlet. You should NEVER use an extension cord for a window AC unit, as this could be very dangerous.
When it comes to filtration, you can find window air conditioners with excellent filters. But you'll need to pay attention, because this is not the standard for all models.
We recommend purchasing a model that filters out allergens, bacteria and dust.
Also, it's a good practice to find a model that has a reusable filter that can be rinsed. Not only will you be able to reuse the filter, saving money, but you'll likely keep your filter cleaner too which will improve the service life and energy efficiency of your window AC unit.
Air Flow Features
Most sliding window air conditioners come with several air speeds so you can crank up the AC or run it on low depending upon your cooling needs. It's a good idea to find a unit that has at least 3 or 4 options.
You may enjoy keeping a small breeze of cool air flowing while you sleep, but during the day require a colder environment. In most cases, the more choices you have, the better.
Another handy feature to consider is programmable cycles. This feature allows you to set your AC unit to shut off automatically or start at a set time. Programming your air conditioner to start cooling before you come home from work means you'll walk into a cool space.
There's a wide range of sliding window air conditioners to choose between, and it's important to find one that fits your window space, room size, and has the features you require. Here are a few of our favorites to help you get started:
Midea U Inverter Window Air Conditioner
The Midea U Inverter Window Air Conditioner just may be the best sliding window air conditioner on the market. It's unique in that it allows you to still open your vertical sliding window and it doesn't block your window as much as other units.
Designed to handle rooms up to 350 square feet, this 8000 BTU unit is the smallest of three model sizes. There's a 10,000 BTU model for rooms up to 450 square feet, and a larger 12,000 BTU size that can handle rooms up to 550 square feet.
The Midea U Inverter originated from an Indiegogo campaign and has since become a best selling window air conditioner. It's "U" shape design means the window actually slides into the top of the unit, which leaves less window opening on each side of the air conditioner. In addition, the noisy part (compressor) of the unit is outside on the other side of the window. This design allows the Midea U Inverter to operate at a quiet 42 dBs!
In addition, the unit can be controlled through an app on your phone (both Apple and Android) and voice controlled through Alexa and Google Assistant, or you can simply use the included remote control.
Not only is the Midea U Inverter Energy Star certified, but in 2020 it also earned Energy Star's Most Efficient Certification. It has a Combined Energy Efficiency Ratio of 15.0, which is among the best on the market!
Easy to install with the included quick-snap bracket, the instructions can be a little confusing. However, there are several great videos including this one made by Midea.
The Midea U Inverter AC unit has all the bells and whistles you'd expect and is designed for single- or double-hung windows with a minimum width of 22-inches and height of 13.75-inches.
LG Smart Window Air Conditioner
The LG LW8017ERSM Smart Window Air Conditioner offers 8,000 BTU of cooling power, which can cool a room up to 350 square feet and plugs into a 115-volt outlet.
This Wi-Fi enabled AC unit has a humidifier that removes 2.2 pints of moisture from the air every hour. It even has a Dehumidifier-Only setting that allows the unit to run without the AC, making it an excellent choice for humid climates.
The unit has an EER rating of 12.1 and has earned its Energy Star certification. It even has an Energy Saver mode that shuts down the fan when the compressor isn't running, which allows the compressor and fan to cycle on and off together.
It's easy to install and operates quietly at 52 dB when at its lowest setting, and 58 dB at the highest setting. The check filter reminder and removable, washable filter helps keep the window AC unit running at peak performance.
Equipped with 3-fan speeds, 4-way air direction control, and Auto Cool, there are plenty of cooling customization options for the 220 cubic feet of air the unit circulates ever minute. In addition, The LG Smart Window Air Conditioner has a 24 Hour on/off Timer, Auto Restart, and a Sleep Mode.
The Wi-Fi features allows you to control your sliding window air conditioner from anywhere with the use of the LG ThinQ app. You'll be able to turn the AC unit on or off, set the temperature, or even change the settings. It's also compatible with Amazon Alexa and Google Assistant! and fits windows 22" to 26" wide x 13" high.
There are two larger models if you need more cooling power. The 10,000 BTU model, which can handle rooms up to 450 square feet, and the 12,000 BTU model designed for large rooms up to 550 square feet.
The PerfectAire 3PASC10000 is a casement slider 10,000 BTU window air conditioning unit that can cool rooms up to 450 square feet.
It's easy to operate and install and comes with an expandable window mounting kit which works for both horizontal sliding and crank-out casement windows.
There are 3 fan and cooling speeds and multiple operating modes to create the exact cooling environment you prefer. The Cool Mode is excellent for warm weather; Fan Mode runs the fan for fresh air circulation when you don't need air conditioning; Dry Mode for those humid days and nights to remove the excess moisture from the air; and Auto Mode which allows the unit to determine the best mode to achieve your desired temperature setting.
The full function remote control has a unique feature called Follow Me. When selected, the remote control becomes a thermostat and monitors the temperature wherever the remote is located. This AC unit will keep cooling until the remote control's built-in temperature sensors reach your desired temperature.
It features a 24-hour programmable timer, 4-way directional louvers, washable filter, and exhaust control where you can choose to circulate the inside air through the room or exhaust it outdoors.
The PerfectAire casement sliding window air conditioner requires a minimum window height of 20.3-inches and a width of 15.5-inches. It has an EER rating of 9.5 and a dB noice level of 56 on low and 61 on high.
SoleusAir Saddle Window Air Conditioner
The SoleusAir Saddle is another unique casement sliding window air conditioner. Its relatively new design is similar to the Midea AC unit above, but instead of the window sliding into the unit from the top, the SoleusAir straddles each side of the window frame, allowing for nearly full use of the window.
The SoleusAir Saddle sliding window air conditioner fits windows 24" to 48" wide with a minimum of 16" height clearance. In addition, the window sill can not be wider than 11-inches. But if you have a sliding casement window that meets the measurement requirements, this may be an excellent option.
Installation is easy and the unit can even be used with a horizontal sliding window, although you won't be able to open and close your window as easily as with a sliding casement.
With the MyTemp sensor, the SoleusAir Saddle cools the room to the location of the remote control, ensuring that you're cool wherever you and the remote are located. It also has a 24-hour timer, energy saver mode and sleep mode, as well as auto restart.
The dehumidifier helps keep you cool and comfortable on humid days and since the compressor is located outside, you'll hardly even notice the unit running. It has a noice level rating of 38 dB.
If you're looking for a budget sliding window air conditioner, the GE AHEC05AC is a great choice. With a BTU rating of 5,000 it's designed to cool small spaces up to 150 square feet, but if you need a little more cooling power GE offers larger models in this line-up.
This entire GE line-up is budget friendly and a consumer favorite. We chose the GE AHEC04AC for our top air conditioners for sliding window list because it's a solid performer that nearly any budget can afford.
It has two cooling and fan speeds and 2-way top adjustable air direction, as well as a dehumidifier that removes 1-pint of moisture per hour. The washable filter is easy to remove and should be cleaned every month.
The GE AHEC04AC window air conditioner comes with an easy install kit, has mechanical controls and operates at 59 decibels. It's designed for windows with a minimum width of 21.875" and height of 13.375".
No list would be complete without mentioning the Frigidaire FFRS1022R1. This consumer-favorite casement sliding window air conditioner has racked up thousands of high reviews, and for good reason. Unfortunately, the model has been discontinued by Frigidaire, however, it is still readily available through many retailers as well as Amazon.
It offers 10,000 BTU of cooling power and can handle rooms up to 450 sq. ft., with dehumidification up to 3.4 pints per hour, and has an EER rating of 10.4. The installation kit is included and the unit plugs into a standard 115-volt electrical outlet.
This vertical window air conditioner requires a minimum window height of 21.5-inches with a width of at least 15.5-inches.
It comes with a full-function remote control which allows for precise adjustments to the temperature and fan speed settings among other adjustments. Or, if you prefer to make setting adjustments on the unit itself, you can use the ready-select electronic controls.
The multi-speed fan has 3 speed settings, and the 4-way air direction control which allows you to direct the air flow exactly where it's needed to keep you cool.
The Frigidaire FFRS1022R1 comes with all the bells-n-whistles. It has a 24-hour on/off timer, auto cool, Energy Saver mode, and Sleep mode. It even alerts you when it's time to check your filter! And there's no need to buy expensive filter replacements, it has a washable mesh filter that can be used over and over.
You may want to opt for the Frigidaire FFRS0822S1. It's the exact same model, only not as large. It offers 8,000 BTUs which is suitable for rooms up to 350 square feet.
Last update on 2022-03-30 / Affiliate links / Images from Amazon Product Advertising API