Selecting a Ductless Mini-Split Unit for Your Home

Ductless mini-split units are an innovative solution for home heating and cooling needs, providing increased energy efficiency and customizable comfort. One of the key factors in ensuring optimal performance and energy efficiency of a ductless mini-split unit is selecting the right size for your space. 

Benefits of Ductless Mini-Split Units for Heating and Cooling

Ductless mini-split units offer several benefits for both heating and cooling needs. Compared to traditional HVAC systems, ductless mini-split units are more energy efficient, quieter, and provide more customizable comfort.

Ductless mini-split units use individual air-handling units that can be placed in specific rooms, allowing for greater temperature control and increased comfort. Additionally, because ductless mini-split units do not require ductwork, they can be installed more easily and quickly. This can result in lower installation costs and less disruption to your home.

In terms of energy efficiency, ductless mini-split units are designed to use less energy than traditional HVAC systems, resulting in lower energy bills and reduced carbon emissions. Overall, ductless mini-split units offer a cost-effective and energy-efficient solution for home heating and cooling needs.

Factors to Consider for Ductless Mini-Split Sizing

When it comes to sizing a ductless mini-split unit, there are several important factors to consider.

Room size is one of the most crucial factors, as the unit's cooling or heating capacity needs to match the room's size to ensure optimal performance. Other factors, such as insulation and climate, can also impact the unit's sizing needs.

It's important to select the correct size unit for your space to ensure optimal performance and energy efficiency. Choosing a unit that is too small can lead to inadequate cooling or heating, while a unit that is too large can result in short-cycling, increased energy consumption, and decreased comfort. It is essential to take the time to properly size your ductless mini-split unit to avoid these potential consequences and achieve optimal performance.

How to Choose the Right Size Ductless Mini-Split Unit

Choosing the right size ductless mini-split unit for your space requires careful consideration and calculation. One of the most common methods for calculating the proper size unit is the Manual J Load Calculation, which takes into account factors such as the size of the room, insulation, windows, and doors. Homeowners can also use online tools and resources to estimate the size unit they need based on their specific needs and preferences.

Collaborating with a professional is crucial to guarantee the proper sizing and installation of your ductless mini-split unit. The HVAC technicians at can offer their expertise and guidance to help you choose the appropriate unit size and guarantee a correct installation, leading to optimal performance and efficiency. Partnering with a professional assures homeowners that their ductless mini-split unit is adequately sized and installed, giving them peace of mind in terms of performance and energy efficiency.

To get an accurate estimate of the mini-split size(s) needed, he or she will perform the following steps:

  1. Measure the Square Footage of Each Room
    A professional will determine the square footage of each room measuring each one’s length by its width and multiplying the two figures. So, if a room is 35 feet long and 25 feet wide, the formula would look like this: 35 x 25 = 875 square feet.
  2. Determine the Approximate BTU Rating
    For an approximate BTU rating, the HVAC professional will multiply the room’s square footage by 25. So, for an 875 square foot room, the formula would look like this: 875 x 25 = 21,875 BTUs. This simple calculation works best for rectangular shaped rooms. However, not all rooms are rectangular – some are circular, triangular, and so on.

Mini-Split BTU Sizing Chart

Area Size BTU
150 to 300 sq. ft. 6,000
300 to 500 sq. ft. 9,000
400 to 650 sq. ft. 12,000
500 to 800 sq. ft. 15,000
600 to 1000 sq. ft. 18,000
800 to 1,300 sq. ft. 24,000
1,000 to 1,650 sq. ft. 30,000
1,200 to 2,000 sq. ft. 36,000
1,400 to 2,300 sq. ft. 42,000
1,600 to 2,650 sq. ft. 48,000
1,850 to 3,100 sq. ft. 56,000

The Pitfalls of an Undersized Ductless Mini-Split:

Choosing an undersized ductless mini-split unit may appear to be a cost-effective solution, but it can result in long-term setbacks. Firstly, an undersized unit will run continuously, leading to higher utility bills and added wear and tear on the system. Moreover, you'll face inadequate heating or cooling power, resulting in hot or cold spots, negatively impacting your comfort. While a smaller mini-split unit may appear to be an affordable option, it will ultimately lead to increased costs and discomfort.

While a larger mini-split with a higher BTU rating may seem like a better choice, it's not always the case. An oversized mini-split can be costly and result in short cycling, which means the system turns off and on frequently for short periods. This can lead to wear and tear and ultimately malfunctions, repairs, and premature failure. Moreover, an oversized unit will not be able to dehumidify the air correctly, resulting in a more humid environment. So while bigger may seem better, it can lead to added expenses and issues such as humidity and dampness.

Factors to Consider for Ductless Mini-Split Sizing

While room size plays a significant role in selecting the right BTU capacity, there are other factors to keep in mind as well. External factors, like environmental conditions, also play a role in determining the size of the unit you will need.

If you’ve ever lived through a Canadian winter, then you know all too well how indoor temperatures can be affected by the outside climate. However, did you know that where you live affects the size of the mini-split you need. For example, if you live somewhere with summer temps that regularly reach 90+ degrees Fahrenheit, you will need to increase the BTU rating of your mini-split unit by 30 percent or more.

Ceiling Height
When it comes to heating and cooling, ceiling height plays just as large of a role in the performance of a mini-split as square footage. The higher the ceilings, the more air there is that needs to be heated or cooled. Most homes have eight-foot ceilings, but if yours are higher, you should increase the BTU capacity of the mini-split you buy by a minimum of 20 percent.

Age of Your Home
Another factor to consider is the age of your home. Due to evolving technology and revised building codes, newer homes are typically better insulated than older homes. If you have an older home with poor insulation, you will need a ductless mini-split system with more power to keep it comfortably cool or warm. If this is the case, you should increase the BTU rating by 30 percent or more. On the other hand, if you live in a newer home with better insulation, it will require fewer BTUs.

Other Factors
Some other factors to consider when calculating your home’s required BTU capacity include:

  • Sunlight
    Direct sunlight can heat up a room in a hurry. The more direct sunlight a room receives, the higher the BTU rating it will need.
  • Doors and Windows
    Since doors and windows aren’t insulated and have cracks and gaps, they allow air to leak in. Therefore, the more doors and windows there are in the zone where your mini-split will be located, the greater the required BTU capacity.
  • Lightbulbs
    Most people don’t think about lightbulbs when determining the size of their mini-split, but lightbulbs generate heat. Furthermore, some types of lightbulbs generate more heat than others.
  • Kitchen
    Stoves and ovens also give off heat. If you want to install a mini-split for your kitchen or a neighboring room, you may need a larger mini-split with a higher BTU capacity.
  • Flooring
    Carpet offers better insulation than hardwoods or tile. While the type of flooring in your home doesn’t play as large of a role as the other factors above, it is still something to keep in mind.
  • Size of Your Household
    Last but not least, people also generate heat and can play a role in sizing your mini-split unit. You need to consider the number of occupants who will be spending time in the room where your mini-split will be.

Calculating the size of the mini-split required for your living space involves a process known as load calculation. This calculation takes into account all the factors discussed, enabling you to determine the amount of cold or warm air required to maintain a comfortable temperature in the area.

While you can perform these calculations yourself using a guide or various online load calculators, it's recommended to seek the assistance of an HVAC technician for a professional consultation. A qualified, experienced mini-split technician will help ensure that you install the exact unit suitable for your home's needs.

Mitsubishi Electric and Bosch Ductless Mini-Split Units

Mitsubishi Electric and Bosch are two of the top brands in the industry when it comes to ductless mini-split units. These brands are known for their high-quality and innovative products that offer superior performance, energy efficiency, and comfort.

Choosing Mitsubishi Electric or Bosch for your ductless mini-split unit ensures that you are getting a reliable and efficient system that will provide years of optimal performance. Both brands offer a variety of features and benefits, including advanced filtration systems, Wi-Fi-enabled controls, and zoning capabilities. 

However, there are some differences between the brands. Mitsubishi Electric units are known for their superior cold weather heating capabilities, while Bosch units offer exceptional energy efficiency and quiet operation. When deciding between these brands, it's important to consider your specific needs and preferences to determine which one is the best fit for your home.

Proper sizing is crucial when selecting a ductless mini-split unit for your home. By choosing the right size unit, you can ensure optimal performance and energy efficiency, resulting in cost savings and increased comfort. Additionally, ductless mini-split units offer several benefits for heating and cooling needs, including increased energy efficiency, customizable comfort, and ease of installation.

If you are considering a ductless mini-split unit for your home, it's worth exploring the benefits of Mitsubishi Electric or Bosch units. Both brands are known for their high-quality and innovative products that offer superior performance, energy efficiency, and comfort. By choosing one of these top brands, you can have peace of mind knowing that you are getting a reliable and efficient system that will provide years of optimal performance.

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