Through-The-Wall Air Conditioners Buying Guide (2025)

Whether you're looking for your first through-the-wall air conditioner or are replacing an existing thru-wall unit, we have everything you need to know about buying the right air conditioner for you. For easy access to the topics in our buying guide, click the titles below.

• How Do Through-the-Wall Air Conditioners Work?
• Thru-Wall ACs vs Window ACs
• Selecting the Right Size
• Installation: Wall & Electrical Requirements
• Replacing an Existing Unit
• Energy Efficiency
• Heat and Other Operating Modes
• Convenience Features
• Are Through-the-Wall Air Conditioners Quiet?

How Do Through-the-Wall Air Conditioners Work?

Through-the-wall air conditioners are self-contained units that can quickly cool rooms and other spaces. They're similar to window ACs but are installed through an exterior wall, using a wall sleeve for support. This makes them a more permanent cooling option without taking up your window view. One advantage is that the position on the wall can be higher up or lower down on the wall, as suits the space. These versatile units have many of the same features that Window AC’s do, including models with heat mode, as well as energy-efficiency and convenience features.

Through-the-Wall ACs vs. Window ACs

Thru-wall ACs and window ACs are similar in cooling capacity and size, but through-the-wall units tend to be slightly more efficient. The major differences between these ACs involve installation and venting.

Through-the-Wall ACs

• Install through an exterior wall, which requires opening a hole in the wall. This may require someone to do the work.
• Include trim for around the AC inside the room, creating an airtight seal.
• Require a wall sleeve to hold the AC. Some models have a slide-out chassis, where the surrounding cabinet functions as the wall sleeve. Read more on wall sleeves.
• Vent only through the back of the air conditioning unit.
• It is ideal for rooms without windows or where the window view shouldn’t be blocked.

Window ACs

• Install in a window with an installation kit and can usually be done by the owner.
• Have side panels that help secure and block outside air but are not air-tight.
• Vent through the back and sides of the unit.
• Best for rooms with more than one window or where the view from the window doesn’t matter.

It is important to note that Through-the-Wall units and Window units are not necessarily interchangeable—even if they’re the same size. This is due to the difference in venting. However, there are Window ACs that can be installed through a wall and are designed with slide-out chassis for this purpose.

If you think a window AC might be a better fit, read our Window Air Conditioner Buying Guide for more information.

Selecting the Right Size

As with all room air conditioners, purchasing a model with the appropriate cooling power is the most important place to start. Through-the-wall ACs measure their cooling capacity using British Thermal Units (BTUs): The higher the number of BTUs, the more area the AC can cool.

Use the chart below to find the ideal cooling capacity for your room size:

Other Sizing Considerations:

• Increase BTUs by 10 percent if your room receives a lot of sunlight and reduce them by 10 percent if it receives very little sunlight.
• Increase BTUs if your ceilings are higher than 8 feet.
• If more than 2 people occupy the space, add 600 BTUs of cooling power for each person.

Installation: Wall and Electrical Requirements

Installing a through-the-wall air conditioner is permanent but not as hard as you may think. Follow the manufacturer's instructions carefully for the safe installation of your model, particularly when it comes to the size of the hole in your wall. The main things to consider before installing your model are which wall you use and the electrical requirements:

• Wall Requirements: The most important part of installation is using an appropriate wall. Before you begin, be sure to check for plumbing or electrical structures that may be inside the wall. Consider consulting a professional if you feel unsure, as the hole needs to be measured and cut precisely.
• Exterior Wall Needed: All thru-wall ACs must be vented outside, so they must be installed in an exterior wall. Also, take into account wall thickness, double-checking both the unit and sleeve dimensions before you start. Consult the owner's manual for any additional requirements.
• Electrical Requirements: Always check the voltage specification for the model selected to ensure that the AC will work in your home. Many new thru-wall ACs use standard 120-volt plugs, but some larger or older units use 220 volts. For models with voltage requirements that don’t match yours, you may need to install special electrical wiring or consult an electrician. Locate the AC on the wall well within reach of an appropriate outlet; most manufacturers don't suggest altering or extending the cord.

Replacing an Existing Unit

Replacing a through-the-wall air conditioner is fairly simple; the main consideration is the wall sleeve. Every through-the-wall air conditioner requires some type of wall sleeve for support. Without this, your wall cannot support the weight of the AC and will become deformed or seriously damaged.

Wall Sleeve Options

When replacing an old unit, the existing traditional wall sleeve is usually compatible with the new model if it’s a similar cooling size (BTUs). Fortunately, many air conditioner brands make standard thru-wall AC sizes that fit sleeves from other brands, so you aren’t limited by that. This makes installation simple. If the sleeve fits, simply buy the new thru-wall unit and install it. You can find information on wall sleeve size in the owner’s manual to check against the size of the one you have.

Note: Most of our units include a link to the owner’s manual on the right side of the product page so you can check before you buy.

A through-the-wall AC with a slide-out chassis essentially uses the surrounding cabinet as the wall sleeve. The AC unit slides out of the cabinet, which is then installed in (through) the wall. The thru-wall AC slides back into the cabinet to complete the installation. Double-check the size of the hole required when replacing an old unit using a traditional wall sleeve with a new unit that has a slide-out chassis.

Sometimes, a wall sleeve is included with the AC. However, traditional wall sleeves generally need to be purchased separately, should you need a new one. Trim or other material can help to seal the area around the unit, so you can use a different sleeve size. See our through-the-wall AC accessory page to view wall sleeves and other accessories to help simplify installation.

Window AC Installation Options

Select window AC models can be installed in either a window or through the wall. This can be helpful if it’s difficult to find a traditional thru-wall model in the right size or voltage to work in your home. These models have a slide-out chassis that vents through the back of the unit.

If you already have a window unit you want to install through the wall, before cutting a hole in your wall, be sure to check out where the air vents are located. ACs that vent only in the back are great for thru-wall installation, but if they also vent out the sides, you need to make sure your wall won't block the vents. This will cause efficiency and possibly safety issues and prohibit your model from working properly, shortening the life of the unit.

Energy Efficiency

Through-the-wall air conditioners are an energy-efficient way to cool your space, particularly in small- to medium-sized areas without access to central air conditioners. Each thru-wall model comes with an Energy Guide Label that's a snapshot of its energy-related information. This label shows:

• The unit's number of BTUs (cooling power)
• Its estimated yearly operating cost
• The Energy Efficiency Ratio (EER) for the unit

The EER is the most common way to measure energy efficiency. This rating takes into consideration how many BTUs per hour are used for each watt of power the AC draws (watts divided by the number of BTUs), and higher EERs mean greater energy efficiency. ACs with an EER of 9.7 or higher are generally considered efficient models and can save you money over time for ACs that are used frequently.

Thru-wall ACs that are at least 10 percent more efficient than comparable models can become Energy Star-rated as determined by the EPA and US Department of Energy. Features that enable these ACs to achieve an Energy Star rating include Eco- or Money-Saver modes and programmable timers, which enable users to program on/off times to avoid over-using the AC. If you purchase an Energy Star unit, you can be confident you've purchased an efficient model.
In addition, maintaining your AC's air filter will increase its efficiency. Be sure to wash or replace air filters as the manufacturer suggests.

Heat and Other Operating Modes

Many through-the-wall ACs offer supplemental heat for winter months, typically using either an electric heat coil or a heat pump. Units with electric heat use a heating coil and a fan to produce and circulate warm air. Heat pumps redistribute heat from the air or ground, using refrigerant to circulate air between the indoor air handler and outdoor compressor. They are generally the more efficient of the two types.

Please note: An air conditioner heat mode is not intended to heat your entire home and should be viewed as supplemental heat for a specific room. Other operating modes include:

• Dehumidify mode helps the AC remove excess moisture from your home.
• Fan-Only mode is ideal for preventing room stuffiness on days when Cool mode isn’t needed.
• Sleep mode is a quieter operating mode that uses less energy.
• Eco- or Money-Saver mode allows the unit to operate at a lower level while monitoring the air and only running the compressor as needed to cool.

Convenience Features

Through-the-wall ACs include various features to make using them as convenient as possible. Look out for these features when purchasing a new AC:

• Digital Controls: Change your settings easily and set more precise temperatures.
• Adjustable Louvers: Direct air to a specific location when needed. Some models have automatic swing louvers that move cool air around your room.
• Remote Control: Allow convenient changing of the set temperature, mode, and fan speed.
• Auto Restart: This function automatically restarts the motor in the event of a power failure and resumes operation in the last programmed setting.
• Washable Air Filters: Reusable air filters collect particles and can be washed instead of replaced.
• Programmable Timer: Program your AC to turn on or off up to 24 hours in advance, saving on energy bills and running only when you need it.

Are Through-the-Wall Air Conditioners Quiet?

Overall, through-the-wall air conditioners are quiet comfort solutions since their design keeps the noisiest part of the unit toward the outside of the room, and indoor trim provides an air-tight seal. Some thru-the-wall units are as quiet as 50 dB, which is about as loud as the refrigerator in your kitchen.

In Summary

Unlike other room air conditioners, through-the-wall ACs offer a permanent cooling solution for rooms or spaces without windows. This includes server rooms, enclosed workspaces, home offices, and more. If you need this type of solution for a larger space or for multiple rooms, consider one of our ductless mini-split AC systems, which are available in single-zone or multi-zone options. If you need a room air conditioner that doesn’t require permanent installation, consider a portable AC or window AC.

Still Have Questions?

For more information on specific thru-wall air conditioners and other indoor air treatment solutions, shop our products and visit our Knowledge Center. Not sure what's best for you? Contact our product experts toll-free at 1-800-934-9194. We want to help you make your indoor environment healthy and comfortable.