As you are shopping for a new air conditioner, there is no doubt you have run across the term BTU. But what exactly are BTUs, and how do you select the right number of BTUs for your home?
The British Thermal Unit
BTU stands for British thermal unit. It’s the amount of energy required to raise 1 pound of water by 1 degree Fahrenheit. This is one time when we use the same system of measurement in the United States that the British do.
BTUs indicate the cooling capacity of your AC system. The more BTUs you have the rawer cooling capacity the air conditioner can provide.
Your air conditioner works by absorbing heat from the air circulating through your system. It then transfers this heat to the air outside. The BTU rating indicates how much heat it can transfer when operating at peak capacity.
The actual BTU capacity is affected by variables such as maintenance of your system, the right refrigerant level, and proper airflow. If one of these is suboptimal, your cooling capacity begins to decline, making your system work harder.
Importance of the Right BTUs
Given the BTU is the raw cooling capacity, it stands to reason that a higher BTU rating is desirable. Unfortunately, Tim Allen would be wrong for adding more power in all instances of air conditioning.
Rather, your air conditioner is more like Goldilocks and needs to be just the right size for your home. If the system is too small, it will run longer and have more frequent cycles trying to keep your home cool.
A higher BTU rating may be able to cool your home more quickly in theory. However, your entire system is designed to pass a certain volume of air. A higher capacity air conditioner does not increase the overall system capacity.
This means a larger BTU rating may lead to problems like a frozen system. In turn, this may lead to running a series of shorter cycles more frequently. These shorter cycles increase the cost of running your system and add unnecessary strain, leading to more repairs.
Larger units also cost more to install, so you are going to pay more for your system upfront. In addition, the minimum energy required to run a larger system is more than a smaller system. This means you end up paying higher operational costs without gaining any additional benefit for your home.
BTUs and Humidity
Part of how your system makes your home comfortable is through the dehumidification effect. Your system brings down the temperature of the air far enough to cause some of the moisture to condense. That’s why it feels so good when you go into an air-conditioned space on a humid day.
To provide this level of comfort, your system must be able to cycle through enough air to provide your desired cooling temperature. However, when your system is oversized for your space, it does not run long enough to produce your optimal cooling temperature.
Another consideration for how BTUs affect your humidity is when the humidity is high. During hotter, more humid days, your system requires a higher capacity to achieve the same level of comfort. If your system is underrated, then it will not be able to keep up on these more intense days.
Selecting the Right Size
The goal is to select the right size air conditioner for your home. To do this, you’ll need to consider the size space you need to cool.
The rule of thumb is to multiply the square footage by 20 BTUs per square foot. So, if your home is 2,300 square feet, then you will need a system with a capacity of roughly 46,000 BTUs.
Then, you need to consider variables that may affect your needs. The primary consideration is how many people occupy your home. For every person more than two, you should increase your capacity by 600 BTUs.
There are several other considerations to consider as well. This includes if your home is shaded, if you entertain frequently, and if you do anything that generates more heat than usual. Working with a qualified HVAC professional is the best way to ensure you are getting the right size air conditioner for your situation.
People around Frederick have turned to Weather Masters Corp. since 2016 for help selecting the right size air conditioner. Our team also provides expert heating and air conditioning maintenance and repair. For more information about air conditioning BTUs, call to schedule your consultation with one of our expert technicians today.