If you are looking for the right size wall mounted air conditioner it’s better to know the steps that help you to solve this task. Many local retailers or even the producers give you only one piece of advice which is to focus on the BTUs. But according to many experiences, it’s not true. You have to pay attention to many factors that are like pieces of the puzzle and they will work only together.
I recommend choosing a well-known brand with very good reviews, feedbacks, and customer service. It would be wasting money if you choose a unit from an unknown producer which has a little bit lower initial price but when even a small issue occurs you won’t be able to buy a spare part or make a deal with the customer service. Therefore, a brand is a very important thing when you’re shopping for through the wall AC.
Measure the Space
When you need to define the appropriate cooling capacity for the best wall mounted air conditioner for your home, you should definitely start with measuring the space. And if I’m talking about the space I mean the floor space of the room where you desire to install a thru the wall AC unit.
Of course, you maybe want to install the cooling machine in one room but you’re planning to cool (or also heat) more than one room together. Of course, it’s possible and I must admit it’s very common. In this case, our goal is to add floor space in square footage for all of the rooms that adjoin and will be cooled.
Tools You Need
- Measuring tape
- Paper
- Pencil
Let’s get started with the shapes of the room and how to measure those ones.
Square Room
You should start to measure the width of the room. Then, simply multiply the numbers.
- Example: 20 feet x 20 feet = 400 sq. ft.
Rectangular Room
If you have a rectangular room the steps are the same as if you have a square room. You should measure the width and length of the room. And then, it’s easy to multiply those two numbers.
- Example: 30 feet x 40 feet = 1200 sq. ft.
Triangular Room
Triangular rooms are pretty common. But no worries. It’s easy as if you have a rectangular room. You should measure the width and length of the longest room sides. In the next step multiply these two numbers. Then, divide them in half.
- Example: 30 feet x 10 feet = 300 sq. ft. , and 300 ÷ 2 = 150 sq. ft.
Unusual Shape of Room
It’s not easy with the unusual shapes of rooms. I know. The goal is to break the room into small pieces with triangular and rectangular shapes. Write the square footage of all pieces and add them together. If you have a problem with defining the pieces you can use a small cheat. Put on the floor and colored vinyl tape.
Try to break your room into small triangles and rectangles. Find out the square footage of all pieces and get them together. The final number use as a parameter in square footage.
Required BTU
The floor space in square footage you obtained is a very important parameter. But why it’s so crucial to know it actually? The size of the room helps us to define the BTU (British Thermal Unit).
When we want to find the proper wall mounted air conditioner for our home, the BTU shows the cooling capacity of the appliance. And we desperately need to define the proper cooling capacity otherwise we can struggle with unpleasant problems.
The first problem that can occur is a problem with a weak wall mounted AC. If your cooling device is too weak, it means the unit is operating as hard as it can but you won’t be able to obtain the desired temperature. It’s wasting energy and money. The machine works but not properly.
The second problem is usually seen if you buy a too strong wall mounted room air conditioner. The thru the wall AC unit is literally too powerful and it’s able to cool the floor space very fast without removing the excessive humidity. Another part of this trouble is the question of energy bills. They will skyrocket for no reason if you don’t need such a strong machine.
In the ideal situation, you should find out the floor space in square footage and find the appropriate cooling capacity in BTU in the table below.
| SQUARE FOOTAGE OF YOUR ROOM | A WIDTH OF A SQUARE ROOM | BTU NEEDED |
| Less Than 150 sq. ft. | Less Than 12 feet | 5,000 BTU |
| 150 – 225 sq. ft. | 12 feet – 15 feet | 6,000 BTU |
| 225 – 300 sq. ft. | 15 feet – 17 feet | 7,000 BTU |
| 300 – 350 sq. ft. | 17 feet – 18 feet | 8,000 BTU |
| 350 – 500 sq. ft. | 18 feet – 22 feet | 10,000 BTU |
| 500 – 650 sq. ft. | 22 feet – 25 feet | 12,000 BTU |
| 650 – 875 sq. ft. | 25 feet – 29 feet | 14,000 BTU |
| 875 – 1,100 sq. ft. | 29 feet – 33 feet | 18,000 BTU |
| 1,100 – 1,300 sq. ft. | 33 feet – 36 feet | 21,000 BTU |
| 1,300 – 1,600 sq. ft. | 36 feet – 40 feet | 25,000 BTU |
| More Than 1,600 sq. ft. | More Than 40 feet | 29,000 BTU |
Defining the cooling capacity in BTU from the table isn’t all. To clarify, you need to involve many other aspects. I significantly recommend not omitting them. They could be crucial when you are deciding between two BTUs you should shop.
First of all focus on these tips:
- If in your home more than two people live you should increase the cooling capacity for about 600 BTU for each additional person permanently living at home.
- If you desire to install the unit into a kitchen or to a kitchen adjoining with another room without a door you should definitely add 4000 BTU to the cooling capacity you need. The reason is the cooking and baking produce heat that is accumulated in the room.
- For well-shaded rooms (there is a tree in front of the room, your apartment is equipped with wooden window shutters, etc.) I recommend reducing the cooling capacity by 10-15%.
- For all rooms that are exposed to the sun for the day-long, I would increase the cooling capacity by 15-20%.
How Is a Unit Size Affected by the Kind of a Room?
In general, the wall mounted air conditioner is ideal for small or mid-sized rooms. I would strongly to use them only for these rooms.
This kind of cooling machine is primarily designed to be used in bedrooms, kitchens, living rooms, dining rooms, or offices. But you should understand all of the rooms are used for a different type of acting or simply living. And you should involve this into your consideration for what is the right size wall mounted AC unit.
If you would like to install the wall-mounted air conditioning unit into a kitchen you should increase the cooling capacity. The best option is to add at least 4000 BTU. But it’s a general recommendation. It’s much better if you start thinking about how often you cook in the kitchen and what appliances use there. For example, if you prepare for breakfast only a toast then the situation with accumulating of the heat will be different compared to baking a quiche with bacon and scrambled eggs.
And if you want to use the through the wall air conditioner in an office or meeting room or maybe in the living room the situation is a bit complicated. Why? Because the number of people isn’t consistent. I recommend thinking about it very intensively and consider all the facts. How often you meet your guests or clients in the room? Every day for many hours or once a week for two hours? It affects your final decision.
The standard appliances are designed to be operated in a room where are two people. If you need to run them on a place with a higher fluctuation of people you definitely have to increase the cooling capacity by 600 BTU for each person. If the number of people changes a lot every day. Try to observe the situation for a few days or weeks and then use an average number of people to define the final needed BTU.
What Is the Size of Sleeve for Your Wall Mounted Air Conditioner?
The wall-mounted air conditioner has vents on the back as well as on the sides. You shouldn’t overlook this important fact. I know many people who thought they could simply slide their old units from other rooms inside the sleeve. But the units weren’t designed for the through the wall installation.
Many brands produce their mounted air conditioner sleeves in standard sizes which means you don’t need the original sleeve or you can use your old sleeve for the AC unit replacement.
You should follow the measurements of your unit along with instructions in the manual provided by the manufacturer. But if you aren’t able to find the original sleeve you the table below to find an appropriate replacement.
| BRAND | HEIGHT | WIDTH | LENGTH |
| Friedrich (USC Sleeve) | 15 17/32″ | 25 7/8″ | 16 23/32″ |
| Amana | 15 5/8″ | 26″ | 16 7/8″ |
| Carrier (51S Series) | 16 7/8″ | 25 3/4″ | 18 5/8″ |
| Fedders/Emerson/Friedrich (WSD) | 16 3/4″ | 27″ | 16 3/4″ or 19 3/4″** |
| Fedders/Emerson | 15 3/4″ | 26 3/4″ | 15″ |
| GE/Hotpoint | 15 5/8″ | 26″ | 16 7/8″ |
| Whirlpool | 16 1/2″ | 25 7/8″ | 17 1/8″ or 23″ |
| White-Westinghouse/Frigidaire/Carrier (52F Series) | 15 1/4″ | 25 1/2″ | 16″, 17 1/2″, or 22″ |
In Summary
I believe my guide helped you to solve your situation and answered the question of how to choose the right size wall mounted AC unit. You should always consider many other factors such as your location, it means where you live, the ceiling height, exposure of windows to the sun during the day, etc. It helps you to define the proper BTU for your new wall-mounted room air conditioner.
Also, I have to point out the fact it’s always better to rely on well-known brands that provide the best way of customer service, required spare parts, required accessories, and high-quality products.