6 Best Through-The-Wall Air Conditioners In 2021 (In-Wall AC Units)

In-wall air conditioner is a type of AC unit that is installed through the wall. All air conditioners take away your living space; portable units cover your floor, window units steer your window, central air has ducts. All of them, of course, except through the wall air conditioner.

Air conditioners that are installed thru the wall are amazing space-savers. More importantly, they are exceptional in cooling spaces up to about 700 sq ft, even during the hottest summers. 

According to the EPA’s statistics and analysis report, in the Northeast US, 58% own some kind of window/wall AC unit. Northeast homes are twice as likely to have a window/wall AC unit than homes in Midwest, South, or West:

how many homes have in wall air conditioners
Window/wall AC units are most prevalent in the Northeast.

If you want to choose the best in-wall air conditioner, you have to do a bit of homework. You have to answer questions like:

What size through the wall air conditioner do I need? (8,000 BTU to 14,000 BTU)

Which brand makes the best in-wall AC units? (Koldfront, Frigidaire, LG)

How to tell if the wall-mounted air conditioner is energy efficient? (EER Rating)

Which is the best in-wall air conditioner currently on the market? 

To help you along the way, LearnMetrics has prepared a quick guide designed for everybody buying a wall-mounted air conditioner.

What is more, given the spec-by-spec comparison and analysis, along with the good track record for reliability, we can tell which are the best choices for in-wall air conditioners in 2021.

You will find the list and comparison of the 6 best thru-the-wall air conditioners below the guide. If you already know a thing or two about the in-wall air conditioner, and this is not your first rodeo, you can skip to the list here:

Skip To List Of Best In-Wall AC Units Here

First of all, it is useful to clear up the terminology here. We all know what in-wall air conditioners are but we use different phrases to describe them. To avoid all the confusion when referring to this type of ACs units, let look at all the names that are used for air conditioners that are installed in the wall:

In-Wall vs Through-The-Wall vs Wall-Mounted vs Built-In Air Conditioners (Clearing Up Terminology)

We don’t have a single designated phrase to name the air conditioners that are installed through the wall. That’s why we use descriptive names, and there are quite of few of them.

Here we’ll list all of them. It’s important to understand they are used interchangeably; they literally mean the same thing. The “best in wall air conditioner” is the same as the “best through the wall air conditioner”. Following are all the names to describe wall AC units:

  • “In-Wall Air Conditioners”. That’s because they are installed and operate inside the wall.
  • “Through-The-Wall Air Conditioner”. This usage is appropriate because the AC literally goes through the door. You don’t need venting as with portable ACs. The unit itself is designed to vent, and has access to indoors as well as outdoors. “Thru-the-wall air conditioner” is just a shorter version of the phrase.
  • “Wall-Mounted Air Conditioners”. In fact, the in-wall air conditioners are mounted inside the wall, not on the wall; the AC doesn’t hang from the wall, it is fixed through the wall. But when you look at it, looks like it’s hanging on the wall like a painting.
  • “Wall Sleeve Air Conditioner”. To install an AC through the wall, a sleeve is used around the unit to help with installation and, more importantly, to prevent vibrations and keeps the noise levels low.
  • “Built-In Air Conditioners”. Quite straightforward; air conditioners that are built inside the wall.

In short, just keep in mind that all these terms are used interchangeably:

In Wall AC = Through-The-Wall AC = Wall Mounted AC = Wall Sleeve AC = Built-In AC

Air conditioners installed within the wall are known by many names.

Now let’s have a look at the 5 basic metrics of in-wall air conditioners:

In Wall AC Units Have Cooling Capacity Of 8,000 BTU To 14,000 BTU

Air conditioners that are built in the wall have a very good range of cooling capacities. Cooling capacity is a specification that tells us how well can an air conditioner cool; cooling power.

The cooling capacity of through the wall air conditioners is measured in BTU units (British Thermal Units).

What are sizes are the sleeve air conditioners?

The smallest in-wall air conditioners have a cooling capacity of 8,000 BTU. Example: Koldfront WTC8001W BTU air conditioner.

The biggest through-the-wall AC units have a cooling capacity of 14,000 BTU. Example: Keystone KSTAT14-2C with 14,000 BTU capacity.

8,000 BTU to 14,000 BTU thru-the-wall air conditioners can also be installed directly under the window.

For comparison, portable AC units have a similar capacity, other window air conditioners can reach a capacity of up to 15,000 BTU with 115V voltage. The best battery-powered AC unit can reach a 2,300 BTU capacity.

It’s important to properly size an in-wall air conditioner. More about that in the section about coverage area.

Thru The Wall AC Heating Capacity (Some Build In ACs Are Heat Pumps)

Some through the wall air conditioner are capable of proving heating output. They don’t work solemnly as a built-in air conditioner; they are, in fact, heat pumps.

The heater installed in the wall-mounted AC units can provide supplemental heating (low BTU) or can be used as a stand-alone heating unit (high BTU).

An example of the best in-wall air conditioner with a supplemental heater is the Koldfront WTC8001W. It can provide 8,000 BTU of cooling output in the summer. In the winter, it can generate up to 4,200 BTU heating output; this can serve as a supplemental heating system parallel to central heating.

The best sleeve air conditioner with a heater is the LG’s superb LT1037HNR model. The AC can provide 10,000 BTU of cooling effect. Now get this, the LG unit can generate a heating output of 11,200 BTU. In fact, the heating output is higher than the cooling output; this is a unique heater-based in-wall air conditioner.

Most in-wall air conditioners, however, are AC-based only. They are very useful in the summer but won’t help heat up your home in the winter.

Coverage Area Of Through The Wall Air Conditioners Is Up To 700 Sq Ft

It’s important to properly size an in-wall air conditioner. The recommended coverage area of every AC is based on the BTU capacity (cooling output).

How big an in-wall air conditioner do you need?

EPA recommends that, for energy-saving operation, you require at about 20 BTU sleeve air conditioner output for every sq ft. That means that if you have a 400 sq ft space to cool, you would need about 8,000 BTU through the wall AC unit.

According to this cooling calculation, the biggest 14,000 BTU Keystone KSTAT14-2C can cool down up to 700 sq ft of space.

However:

It’s better to be safe than sorry. Picking too small wall-mounted air conditioner is the biggest fear here. You went through all the installation process, using a sleeve around the in-wall air conditioner, and only then you find out the cooling is not adequate for your square footage.

It’s better to use 22 BTU or even 25 BTU per 1 sq ft.

That means that the best wall-mounted air conditioner – the 8,000 BTU Koldfront WTC8001W – can cool down areas with a total square footage of up to 350 sq ft.

If you’re not sure how big your through-the-wall air conditioner should be, you can describe your situation in the comments below, and we’ll try to figure out how many BTU AC you need or you can use our BTU calculator here.

How Energy Efficient Are In Wall Air Conditioners? (EER Rating)

A more efficient in-wall air conditioner means you will pay less for electricity for the same cooling effect. It’s only natural that you should be looking for the most energy-efficient sleeve air conditioners.

How do we know which in-wall air conditioner is efficient and which is not?

EER rating. This is a basic energy-efficiency specification (Energy-Efficiency Ratio Rating). The higher the EER rating, the more energy-efficient in-wall air conditioner you’re looking at.

Portable units have an average EER rating of about 8.5. Window air conditioners are better, with almost a 10 EER rating. The best in-wall air conditioner units in the table below have an EER rating of 10 or more.

In fact, some of them have an extremely high EER rating and are the ultimate cost-saving units. Example: In-wall air conditioner with the higher EER rating is the Friedrich CP08G10B. It has a, get this, 11.2 EER rating which is just outstanding.

How Reliable Are Wall Sleeve Air Conditioners? (Brand Importance)

In-wall air conditioner can last up to 15 years. That’s quite a long time, but it can be reduced if you choose an unreliable thru the wall air conditioner.

Required installation hardware with a sleeve; every in-wall AC producer has their own kit.

The best guarantee for reliability is a well-known recognizable brand. Big brands have a good track-record and tend to make more reliable wall-mounted air conditioners.

Which are the best through the wall AC unit brands?

Koldfront, Frigidaire, LG, Friedrich. These are the bigger brands with ample history and an overall good reputation.

Smaller brands that make top-rated in-wall air conditioners are Midea and Keystone. Midea, for example, has made tremendous leaps in the past few years. They invest in new models, have proprietary tech, and are surprisingly affordable.

Example: MIDEA MAT08R1ZWT 8,000 BTU model is actually the cheapest in-wall air conditioner; it costs less than $400 which is just unheard of (it’s a smaller 8,000 BTU model, that needs to be taken into account, of course).


With all these specifications in mind, a word needs to be said about the in-wall AC installation. With the use of the sleeve and an installation kit, the installation is easier than it looks. Of course, drilling a hole in the wall is a robust and difficult part; slipping the AC into the wall hole is actually quite easy.

Sleeves for installation usually need to be bought separately; it costs anywhere between $100 and $150 for a majority of units.

Let’s have a look at the best wall-mounted air conditioners you can buy in 2021:

Best Through The Wall Air Conditioners In 2021 (Comparison)

  1. Koldfront WTC8001W: Overall Best Through The Wall Air Conditioner.
  2. Frigidaire FFTA123WA1: Best 12,000 BTU Through The Wall AC Unit.
  3. LG LT1037HNR: Best Through The Wall Air Conditioner With Heater (by LG).
  4. MIDEA MAT08R1ZWT: Cheapest Through The Wall AC Unit (below $400).
  5. Keystone KSTAT14-2C: Best Big Through The Wall Air Conditioner (up to 700 sq ft).
  6. Friedrich CP08G10B: Most Energy-Efficient In Wall Air Conditioner.
Thru The Wall AC: #1 Koldfront WTC8001W #2 Frigidaire FFTA123WA1 #3 LG LT1037HNR #4 MIDEA MAT08R1ZWT #5 Keystone KSTAT14-2C #6 Friedrich CP08G10B
Photo:
Cooling Capacity: 8,000 BTU 12,000 BTU 10,000 BTU 8,000 BTU 14,000 BTU 8,000 BTU
Heating Capacity: 4,200 BTU / 11,200 BTU / / /
Coverage Area: Up to 350 sq ft Up to 550 sq ft Up to 450 sq ft Up to 350 sq ft Up to 700 sq ft Up to 300 sq ft
EER Rating: 10.9 10.5 10.0 10.6 9.3 11.2
Power, Voltage, Amps: 890W (115V, 7.8 A) 1140W (115V, 10.0 A) 1000W (220V, 6.1 A) 754W (220V, 7.0 A) 1500W (230V, 20 A) N/A
Price: $$$$ $$$$ $$$$ $$$$ $$$$ $$$$
Average Rating: 4.8 out of 5 stars 4.8 out of 5 stars 4.8 out of 5 stars 4.5 out of 5 stars 4.5 out of 5 stars 4.5 out of 5 stars
Availability: Check Price Check Price Check Price Check Price Check Price Check Price

1. Koldfront WTC8001W (Overall Best Through The Wall Air Conditioner)

Koldfront WTC8001W: Overall Best Through The Wall Air Conditioner.
Cooling Capacity: 8,000 BTU
Heating Capacity: 4,200 BTU
Coverage Area: Up to 350 sq ft
EER Rating: 10.9
Power, Voltage, Amps: 890W (115V, 7.8 A)
Dimensions (HxWxD): 20.38″ x 24.25″ x 14.5″
Weight: 66.6 lbs
Price: $$$$
Rating: 4.8 out of 5 stars

Koldfront WTC8001W is the top-rated in-wall air conditioner. It’s the go-to standard-sized AC unit that everybody can install themselves. 

This is a smaller 8,000 BTU air conditioner that can be installed through the wall. The 8,000 BTU is enough to cool down spaces up to 350 sq ft. You can install it pretty much anywhere: in the living room, bedroom, kitchen, kids room, you name it.

The very useful part is the supplemental heating. In addition to having an 8,000 BTU cooling output, the Koldfront WTC8001W can also provide 4,200 BTU heating output and all that with the standard 115V voltage.

Koldfront WTC8001W has one of the highest energy-efficiency ratings among the top in-wall air conditioners. With an EER rating of 10.9, it’s more efficient than almost all portable AC units, and it’s the #2 most efficient wall air conditioner. This is very important: the high energy-efficiency equates to lower electricity expenditure. 

The unit itself has both a manual and remote control (via remote controller). You can 3 fan speed setting with an auto option and the 4-way air directional louvers. That gives you the freedom to adequately adjust the cooling effect to your needs.

The drawback is that while it’s super easy to install Koldfront WTC8001W thru the wall, you have to buy the sleeve separately. The sleeve model is WTC8001WKIT and it costs about $100, adding to the admittedly very low below $500 price of the unit.

All in all, the Koldfront WTC8001W is the go-to and top-rated in-wall air conditioner. It’s very cost-effective, uses less electricity, easy to install, and can even provide supplemental heating in the winter:

Pros
  • Top-rated thru the wall air conditioner
  • Very high energy-efficiency with 10.9 EER rating and 9.6 CEER rating
  • 8,000 BTU cooling effect AND 4,200 BTU supplemental heating power
  • Best-selling in-wall air conditioner
  • Koldfront is one of the most reliable HVAC brands
Cons
  • Sleeve for installation has to be bought separately; it costs about $100, raising the very affordable cost of the unit

2. Frigidaire FFTA123WA1 (Best 12,000 BTU Through The Wall AC Unit)

Frigidaire FFTA123WA1: Best 12,000 BTU Through The Wall AC Unit.
Cooling Capacity: 12,000 BTU
Heating Capacity: /
Coverage Area: Up to 550 sq ft
EER Rating: 10.5
Power, Voltage, Amps: 1140W (115V, 10.0 A)
Dimensions (HxWxD): 20.62″ x 24″ x 14.5″
Weight: 90 lbs
Price: $$$$
Rating: 4.8 out of 5 stars

Frigidaire is the biggest HVAC brand that produces in-wall air conditioners. Their best unit is the Frigidaire FFTA123WA1; the best 12,000 BTU through-the-wall air conditioner with an Energy Star rating.

Frigidaire FFTA123WA1 is used to cool down larger spaces. With the 12,000 BTU cooling capacity, the Frigidaire FFTA123WA1 model is capable of lowering the indoor temperature in spaces up to 550 sq ft. The easy installation is a given, but even more important is the long-term energy efficiency:

This unit can produce 12,000 BTUs with only 1140W of power; it has an EER rating of 10.5. In short, it is very energy-efficient and actively lowers the cost of electricity (especially on lower fan speed settings). For the high energy efficiency, this best Frigidaire sleeve air conditioner was also awarded a coveted Energy Star rating.

Across the board, Frigidaire makes very reliable wall air conditioners. The Frigidaire FFTA123WA1 is a bigger 12,000 BTU energy-efficient in-wall air conditioner that will easily last for 10+ years:

Pros
  • Best Frigidaire in-wall air conditioner
  • 10.5 EER rating with Energy Star rating (very energy-efficient and electricity-saving unit)
  • Can cover up to 550 sq ft due to 12,000 BTU cooling capacity
  • Frigidaire is the biggest brand that makes in-wall AC units; best guarantee for reliability
Cons
  • Sleeve for installation has to be bought separately; costs about $110
  • Weighs 90 lbs; you’ll need strong hands for installation

3. LG LT1037HNR (Best Through The Wall Air Conditioner With Heater)

LG LT1037HNR: Best Through The Wall Air Conditioner With Heater (by LG).
Cooling Capacity: 10,000 BTU
Heating Capacity: 11,200 BTU
Coverage Area: Up to 450 sq ft
EER Rating: 10.0
Power, Voltage, Amps: 1000W (220V, 6.1 A)
Dimensions (HxWxD): 20.09″ x 24″ x 14.41″
Weight: 70 lbs
Price: $$$$
Rating: 4.8 out of 5 stars

LG LT1037HNR is a very unique in-wall air conditioner. To produce it, you really need the LG engineering expertise with not only ACs but heat pumps as well. This is the best in-wall air conditioner with a heater (a true heater, that is).

The 10,000 BTU cooling effect is enough to cool down areas up to 450 sq ft. That’s the basic function of every wall-mounted air conditioner.

The additional advantage LG LT1037HNR has is the best heater in any wall air conditioner. The 11,200 BTU heater is out of this world; this AC can actually produce more heating output than cooling output. You can use it both in the summer and in the winter; that makes it quite unique.

Mind you, we’re not talking about supplemental heating. The 11,200 BTU heating output is like a little furnace; it will heat up a room on its own. For that, however, it will need a 230V voltage, to lower the amps when generating all this heat.

LG LT1037HNR has an EER rating of 10. Quite simply, 10,000 BTU cooling output is generated with 1,000W input. In short, it is an efficient in-wall air conditioner. On top of that, LG has also analyzed the energy-efficiency and produced a CEER (combined EER) rating of 9.7.

On the whole, the LG LT1037HNR is the best wall-mounted air conditioner with a heater. It can be used year-round and saves costs in terms of electricity, and you don’t have to buy a separate heater:

Pros
  • In-wall AC unit with the best heater (11,200 BTU heating)
  • Energy-efficient with a 10 EER rating
  • The only truly year-round wall heat pump
  • LG is an HVAC-based business; they know what they are doing (reliability)
Cons
  • Higher price due to addition of the heater
  • Needs 230V; doesn’t run on 115V

4. MIDEA MAT08R1ZWT (Cheapest Through The Wall AC Unit)

MIDEA MAT08R1ZWT: Cheapest Through The Wall AC Unit
Cooling Capacity: 8,000 BTU
Heating Capacity: /
Coverage Area: Up to 350 sq ft
EER Rating: 10.6
Power, Voltage, Amps: 754W (220V, 7.0 A)
Dimensions (HxWxD): 20.3″ x 24.2″ x 14.5″
Weight: 75.9 lbs
Price: $$$$
Rating: 4.5 out of 5 stars

MIDEA is a newer company that has made a tremendous impact on the in-wall AC market with surprisingly low-cost units. The MIDEA MAT08R1ZWT is the cheapest thru-the-wall air conditioner you can get; it actually costs less than $400.

The 8,000 BTU MIDEA MAT08R1ZWT produces can be used to cool down rooms with a total square footage of up to 350 sq ft. Essentially, it is a small room in-wall air conditioner. 

MIDEA MAT08R1ZWT is quite an energy-saver. This built-in AC unit has an EER rating of 10.6. That’s even more than the LG unit. This can translate into some serious electricity-bill savings over the next 10+ years.

It doesn’t, however, have a heating function. If you’re looking for a year-round unit, the MIDEA MAT08R1ZWT definitely isn’t it. But the lack of heating function also affects the price of the unit itself:

In fact, the combination of a small 8,000 BTU unit, no heater, and MIDEA pricing makes the MIDEA MAT08R1ZWT the cheapest through-the-wall air conditioner in the market. Most units cost more than $500. MIDEA MAT08R1ZWT is the only one that costs less than $400. With high energy-efficiency, the short-term, as well as long-term costs, are super low.

All in all, if you need a price-performance energy-efficient in-wall air conditioner, MIDEA MAT08R1ZWT is one of the best choices. It’s also the cheapest AC unit that can be installed thru-the-wall:

Pros
  • Lowest unit price (below $400 for 8,000 BTU unit)
  • Low long-term costs due to high energy-efficiency (EER rating = 10.6)
  • Decent materials used and MIDEA is getting a reputation as a reliable HVAC producer
Cons
  • Doesn’t have a heater
  • MIDEA is not yet one of the big brands like Koldfront, Frigidaire, and LG

5. Keystone KSTAT14-2C (Best Big Through The Wall Air Conditioner)

Keystone KSTAT14-2C: Best Big Through The Wall Air Conditioner
Cooling Capacity: 14,000 BTU
Heating Capacity:  /
Coverage Area: Up to 700 sq ft
EER Rating: 9.3
Power, Voltage, Amps: 1500W (230V, 20 A)
Dimensions (HxWxD): 24.2″ x 20.3″ x 14.5″
Weight: 78.3 lbs
Price: $$$$
Rating: 4.5 out of 5 stars

If you’re already drilling a hole in the wall, it sure seems a good idea to put as big an air conditioner in there as possible, right? That’s the reasoning behind the Keystone KSTAT14-2C. While most in-wall ACs can produce 8,000 BTU or 10,000 BTU of cooling power, the Keystone KSTAT14-2C can overpower them:

Keystone KSTAT14-2C can produce an incredible 14,000 BTU of cooling effect. It’s the most powerful in-all air conditioner. It needs 230V and is powered by 1,500 watts of energy. It’s quite a powerhouse.

14,000 BTU is enough to cool down up to 700 sq ft (realistically, 600 sq ft would be a safe number). That means that Keystone KSTAT14-2C is an in-wall air conditioner with the highest coverage area. If you have a small house, the Keystone KSTAT14-2C can be the only AC you will need. And it takes no space; it’s simply installed within the wall.

The drawback is the average-only energy efficiency. The EER rating of 9.3 doesn’t make the Keystone KSTAT14-2C one of the more efficient units; again, it is a powerhouse with 1,500W.

All around, the Keystone KSTAT14-2C is the most cooling power you can insert into the hole in the wall. With 14,000 BTU, it’s a powerhouse, and can cool down rooms with a combined square footage of up to 700 sq ft:

Pros
  • Biggest in-wall air conditioner (highest cooling effect)
  • Can produce, get this, 14,000 BTU cooling output, enough to lower temperature in up to 700 sq ft
  • Has a temperature sensing “follow me” remote control
Cons
  • Energy efficiency is average-only: EER rating = 9.3
  • Needs 230V to run
  • Keystone is not the biggest brands out there

6. Friedrich CP08G10B (Best Highly-Efficient Small Through The Wall AC Unit)

Friedrich CP08G10B: Best Highly-Efficient Small Through The Wall AC Unit
Cooling Capacity: 8,000 BTU
Heating Capacity:  /
Coverage Area: Up to 300 sq ft
EER Rating: 11.2
Power, Voltage, Amps: N/A
Dimensions (HxWxD): 20.88″ x 18.38″ x 14″
Weight: 64 lbs
Price: $$$$
Rating: 4.5 out of 5 stars

Friedrich is an HVAC company that employs top engineers, and it shows. Their in-wall AC unit Friedrich CP08G10B has, by quite a margin, the highest energy-efficiency among the sleeve air conditioner.

Friedrich CP08G10B is a small and compact unit. It’s capable of producing up to 8,000 BTU which can cover about 300 sq ft. In short, it is a small room in-wall air conditioner.

The true jewel is the low long-term electricity costs due to the record high energy-efficiency. Friedrich engineers managed to create a wall AC with, check this out, 11.2 EER rating. That’s just tremendous.

According to Friedrich CP08G10B’s EnergyGuide label, the 11.2 EER rating assures that you will spend only $62 if you run this 8,000 BTU unit 8 hours per day during the 3-month long summer season. Of course, this is an estimate, based on the electricity cost and so on, but $62 is as low as you can go with adequately cooling 300 sq ft room for 3 summer months.

Friedrich CP08G10B, however, is not without its shortcomings. It won’t be enough to cool down bigger rooms and it doesn’t have a heater. It does come with a sleeve included.

Overall, despite being last on the list, Friedrich CP08G10B is quite tremendous. The problem is that it’s quite small (for 300 sq ft or less) but it has the record high energy-efficiency that lowest the on-going electricity costs to the minimum:

Pros
  • Most energy-efficient small in-wall AC unit (EER rating = 11.2)
  • EnergyGuide’s yearly energy cost to $62 in total; as low as you can go
  • The sleeve is included in the price
Cons
  • Can’t adequately cool down 300+ sq ft places (only for smaller rooms)
  • Doesn’t include heater

If you have any additional questions about in-wall AC units, you can pose them in the comments below, and we’ll try to find the answer together.

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