How HVAC Sizing Works

Posted: 2020-08-20

When buying a computer, getting one with a fast central processing unit (CPU) means the system is speedy. Of course, other parts need to be considered, such as memory and video cards, etc. Nevertheless, the CPU determines the speed of the computer, for the most part. However, buying an HVAC system, like an air conditioner, works differently. Purchasing the most robust and feature-packed system doesn’t necessarily mean purchasing the right one for your home.

There are several issues associated with an improperly sized HVAC system, such as inconsistent heating or cooling. You will notice that some rooms are more comfortable than others, which is not a beneficial thing for anyone.

Perhaps the more obvious problem of a system that’s not sized correctly is that you to have excessively high energy bills and many system failures. Since the unit works in imperfect situations, it tends to short cycle (an oversized system) or overheats (an undersized system).

Four Seasons Air Specialists is your trusted HVAC company in White Bear MN. We have more than four decades of experience helping homeowners like you find the right-sized comfort systems.

A Myth Debunked

In the past, contractors used to go by “rule of thumb” when sizing an HVAC system for a home. Frequently, homeowners will have their units professionally installed, and as long as it works, they have no problem with it. As a result, a lot of homeowners bought systems that were too powerful for their homes. 

However, things have improved in recent years. Today, stricter building codes are considered, including the sizing of HVAC systems, making inaccurate sizing methods unacceptable.

What to Consider When Sizing an HVAC System

To make sure your next HVAC system is of the right size, you will need the help of an HVAC professional. The idea is to choose the system that fits your needs, ensuring you won’t be paying for wasted energy.

One of the things to assess when sizing your furnace is the size of the space that needs cooling or heating. This factor will inform you of what size is perfect for your home. Also, the number and frequency of ducts to move the heated or cooled air throughout your home are essential in determining the right unit.

Other important factors include the following:


The climate in your region directly affects your home’s overall comfort level. For instance, you won’t need a system that is too powerful if you live in an area with moderate climates.

Home’s Design

The architectural makeup of your home isn’t only essential to make it look how you want. It also contributes to the specific unit you need to maintain a comfortable indoor environment. The shape, orientation, number of floors, and materials used must all be taken into account when deciding on an HVAC system.

A home with multiple levels is much harder to heat or cool than a home without upper floors. Since heat naturally rises, the higher levels are relatively hotter than the lower levels. Also, having two rooms of the same square footage won’t necessarily need the same furnace or air conditioner size if one has multiple levels.


The position, number, and type of windows affect the amount of radiant heat coming through. Moreover, older, inefficient windows quickly release heated or cooled air.


Buying the right HVAC system for your home also involves determining what type and quality of insulation you have. Proper insulation is vital in maintaining the desired temperature in your home. If your home has poor insulation, the money you’re paying to heat or cool your home practically goes out the window.

On the other hand, when your home has good insulation, your furnace or air conditioner will need less energy to perform its job since insulation blocks heat movement. As a result, you’ll be enjoying lower utility bills and less strain on the system.

Want to Do it Right? Call Four Seasons Air Specialists

We’d love for you to have an HVAC system that fits your needs. Allow us to help you determine the factors mentioned above and help you find the perfect furnace, heat pump, or AC for your home. We have HVAC professionals with multiple years of experience and mastery of home comfort systems, which can guide you throughout the process. We are your reliable North Oaks heating and air conditioning company.