How do I Know What Size HVAC I Need?

May 10, 2022

When looking to install a new HVAC system in your home, it’s important to choose a unit that is sized appropriately. At a glance, estimating the size for your home’s HVAC system can seem daunting or even overwhelming when in reality it can be broken down into a simple equation. However, if you fail to size your unit appropriately and choose a unit that’s too big, the longevity of your machine may be shortened and you may ultimately have dehumidification problems. If you end up choosing a unit that’s too small, you won’t be able to regulate the temperature of your entire home which ultimately defeats the purpose of installing your HVAC system. 


In this article, we will dive into the specifics of choosing an appropriately sized HVAC system in addition to learning about the benefits of hiring a professional.


Step 1: Determine the Square Footage of Your Home 

In order to choose an appropriately sized HVAC system for your home, you must first determine the square footage. Determining the square footage of your home will help ensure that you’re able to choose a machine that heats and cools your home without a hitch.

You may already know the square footage of your home or have it written down somewhere that you can quickly reference. If not, you can manually calculate the square footage of your home by using a tape measure to determine the length and width of each room and repeating the process for each room and hallway until you’ve accounted for the space in your entire home. After you’ve completed this process, you can add each sum together and you will be provided with your total square footage. 


Step 2: Determine Your British Thermal Unit (BTU)

After you’ve determined the square footage of your home, it’s time to move on to the second part of the equation which is determining your BTU. Your BTU refers to a unit of measurement that gauges how much energy your air conditioner uses to remove heat from your home within an hour.

The approximate amount of energy used to cool a square foot of your home is 25 BTUs. Now that you’ve determined your square footage, you can multiply that sum by 25 to get your base BTU measurement.


Step 3: Account for High Ceilings

High ceilings mean more space, leading to more coverage for your HVAC unit. If the ceilings in your home are over 8 feet, you will want to make sure to multiply the base BTU amount by 1.25 or 25%. For a 1500-square-foot home with ceilings that don’t exceed 8 feet, the final sum would be roughly 37,500 BTUs.


Step 4: Draw Your Conclusion 

Now that you’ve done the leg work, it’s time to determine the size of your HVAC system. For your air conditioner, divide the number by 12,000 to determine the tonnage required. For your furnace, divide the BTU by the unit’s efficiency as a decimal. For a 1500 sq. ft. home, your air conditioner would need to be 37,500 ÷ 12,000, which equals approximately 3 tons. For your furnace, an 80% efficiency unit would need a BTU output of about 37,500 × 0.8, which equals approximately 47,000 BTU.


Request a Quote or Consult a Professional 

Like any major decision, it’s best to consult a professional. Ultimately, this is a large purchase and it may end up being a costly venture if you don’t consult with a heating and cooling expert before making your final decision. Request a quote or contact Plumbhouse today to ensure your home’s temperature is maintained year-round. 


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May 10, 2022 9:37 am

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