What Size Air Conditioner Do I Need?

Presidential Heating & Air Conditioning

Gaithersburg HVAC Contractors

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Determining what size air conditioner your home needs is a challenge. However, it is very important to get the size right. Otherwise, homeowners run the risk of using more energy than they need and seeing excessively high energy costs or getting an HVAC unit that is too small and not capable of cooling the home properly.

Although the most effective way to determine the size air conditioner you need is to consult with an HVAC professional, homeowners can get a general idea of what size air conditioner they need through simple formulas and calculations. The following is a complete overview of how to determine the most appropriate size for your HVAC unit.

How Are Air Conditioners Sized?

Air conditioners are sized by tons. The larger the HVAC unit, the more square footage it can effectively keep cool. For residential homes, the average air conditioner size can range anywhere from 1.5 tons to 4 tons.

Perhaps the primary determining factor in how large your HVAC unit should be is the square footage of your home, but there are other determinations to make as well (consider the climate zone you live in).

It is also important to understand other notable sizing variables with HVAC units, including British thermal units (BTUs). BTUs are the international measurement of energy. As it relates to the HVAC industry, BTUs refers to the amount of heat an HVAC unit can remove from a home per hour.

While there are a variety of tables available to directly relate the number of square feet to tons, working with BTUs provides homeowners with a more precise measurement of the size of the HVAC unit they will need. Although, as mentioned, there is a range of variables to consider, a tentative correlation between air conditioning tons and BTUs is as follows:

• 1.5 tons = 18,000 BTUs
• 2 tons = 24,000 BTUs
• 2.5 tons = 30,000 BTUs
• 3 tons = 36,000 BTUs
• 3.5 tons = 42,000 BTUs
• 4 tons = 48,000 BTUs
• 4.5 tons = 54,000 BTUs
• 5 tons = 60,000 BTUs

As you can see, each half-ton of cooling capacity correlates to approximately 6,000 BTUs. Of course, the goal is to determine how many tons you will need to cover the amount of square footage your home has while also considering other factors. However, it is important to understand BTUs to make the determination easier.

Calculate by square foot

Now that you have a better understanding of how air conditioners are sized, let’s look further into how to calculate the size of the air conditioner needed based on square footage.

Once again, there are many variables to consider, but a general rule of thumb is that you will need 12,000 BTUs per 400-600 square feet. To help you estimate the size of the HVAC unit you will need, we calculated the BTUs you will need to keep your home at the desired temperature without excessive energy usage is as follows:

• 500 square feet = 12,000 BTUs
• 1,000 square feet = 24,000 BTUs
• 1,500 square feet = 36,000 BTUs
• 2,000 square feet = 48,000 BTUs
• 2,500 square feet = 60,000 BTUs

Therefore, if you have a home that is 2,000 square feet, then you will need approximately 38,000 BTUs to keep your home cool. If you compare this to the BTUs to the tons of cooling capacity listed above, you will likely need an air conditioner with four tons of cooling capacity.

Unfortunately, however, calculating the most optimal cooling capacity is not always this easy, and there are other factors that are involved. However, calculating the square footage will give you a general idea of the amount of cooling capacity (in tons) your home will require.

Consider the climate zone you live in

If you hire a professional HVAC technician to evaluate and determine the size of the air conditioner you need, they may conduct what is called a Manual J Load Calculation. A Manual J is a calculation to determine the size HVAC unit you will need by considering all variables.

The additional variables may include the floor plan, wall position, building materials, and climate zone that you live in.

The climate zone, in particular, is important. The warmer the climate you live in, the more cooling capacity you will need to keep your home cool. For example, if you have a 2,000 square foot home and live in a climate zone that is considered around average temperature relative to other locations inside the United States, then the 4 tons of cooling capacity discussed previously will likely work.

However, if you live in a climate zone that is much warmer than average, then you will likely require either a 4.5-ton cooling capacity or a 5-ton cooling capacity with your air conditioner. On the other hand, you may only need a 3.5-ton cooling capacity or a 3-ton cooling capacity if you live in an area that is much cooler.

To give a local example, those who live in Gaithersburg, MD, which is slightly cooler than the average climate in the United States, will require less cooling capacity than a home located in the southern part of the United States. But you will need still more cooling capacity than areas farther north that have colder weather.

Contact the Maryland HVAC Experts

Although you can get a basic idea of the size air conditioner you will need to cool your home by calculating your square footage and the climate you live in, the best way to determine the necessary cooling capacity is to consult with HVAC professionals.

Our team at Presidential Heating and Air Conditioning is here to help those in Maryland with their HVAC needs, and our friendly team is more than happy to answer any questions you have about what size air conditioner you need. To learn more, feel free to reach out to us via phone or email, and we can discuss your HVAC needs in greater detail.