Why House Size Maters When Selecting The Proper HVAC System

August 8, 2018

Need a new furnace? Looking at new air conditioners? The numbers can all get a little confusing as you start comparison shopping.

When you are in the market to replace your heating and cooling equipment, buying the biggest and most efficient won’t necessarily give you the right size for your home. Some are too large. Some are too small. And finding the right one requires a combination of knowing the proper criteria and having the experience to put the information together, formulating the perfect package for your home.

Today’s technology makes the process a lot easier, with software used to aid in the final decision. But the final determination is still up to the professional you hire to install your equipment in your home. Hire the wrong HVAC company and you’ll be paying too much for years to come.

When you install the right size furnace, air conditioner, heat pump, or complete HVAC system, you’ll have a system that provides consistent indoor comfort for you and your family. You’ll also save energy, as a system that is too large or too small wastes energy.

Selecting an energy efficient model is being a smart consumer. Selecting an energy efficient model allows you to take a whole house approach to curbing your energy bills. The capacity of your equipment needs to match the size of the area being heated or cooled, and it must take in key factors to do so.

What happens when an HVAC company installs a system too large or too small?

A number of issues can arise when you have an incorrectly-sized HVAC system in your home.

Too Large – a system that is too large for your living space creates the following problems:

  • It uses too much energy because it takes more energy to operate a larger system
  • It wastes energy through short cycling, turning itself on and off repeatedly and running for only a short time
  • It creates unnecessary noise as it pushes excessive air through the ductwork
  • It creates large temperature swings from not properly cycling
  • It creates more wear and tear on the system
  • It fails to remove sufficient humidity from the air as it doesn’t properly run throughout the cycle

Too Small – a system that is too small for your living space creates the following problems:

  • It runs continuously trying to achieve proper comfort levels
  • It might require supplemental heating and cooling solutions for you to reach your ideal temperature
  • It can create noise in ductwork as the ducts are smaller than required to service your home’s needs
  • It is more likely to malfunction since it runs continuously
  • It will require more maintenance to keep it operating over time

Properly Sized System – when a system is properly installed in your home by a reputable HVAC company, these are the benefits:

  • It operates at optimal efficiency, saving you money in energy costs
  • It keeps your home at the proper temperatures, with every room being comfortable and consistent
  • It provides proper humidity control, increasing comfort level and reducing the chances of biological growth
  • It operates without excessive noise
  • It operates according to manufacturer’s guidelines, without overburdening the system and shortening its lifespan

What factors go into the decision of selecting the right sized heating and cooling equipment?

There are many different considerations that a good HVAC company will use to find the proper size equipment for your home.

Size of your home

The size of your home is an automatic place to start. A 1,000 square foot home will need different equipment than a home 3,000 square feet in size. But there are many other considerations too. Is a home open concept? Does it have large or small rooms? How many windows does the home have? Does the living space face north or south? Even similar homes on different lots can have different needs.


Think all homes in your area are the same? Think again. A home tucked down by the river has different needs than a home placed in a rural area with large open spaces. When the sun shines, does your home benefit by soaking up the energy? Or is it tucked into the forest, rarely seeing the sun’s rays? The quality and amount of insulation makes a difference, as well as how the home is constructed. A brick home differs from wood construction. Even landscaping can impact the requirements for larger or smaller equipment.


We all live in our own unique ways. A family with teenagers operates differently than a single person living alone. Lights and other heat-generating appliances and electronics can increase or decrease your efficiency levels.

Can you do the calculations yourself?

Head online and do a quick search and you’ll find basic HVAC load calculators available for your use. The question is: should you use them?

They’ll ask a few basic questions: the style and type of your construction, your insulation values, how many windows you have, the dimensions of your home. Then it’ll pop out a few calculations: number of Btu’s needed and nominal tons.

None of these measurement are difficult to find or use. But they are fairly involved and take time and patience to complete.

The problem lies with your expertise. If you find your HVAC load calculations once in twenty years, are you taking into account all the factors that impact your final decision?

Commissioning an HVAC company to handle your heating and cooling load calculations can save you the stress of doing the calculations on your own.

It can also help you avoid erroneous calculations, which occur because of lack of experience. Because technicians perform this service on a regular basis, they understand what to look for and what to consider. They not only use a specialized computer program to air in finding the most accurate calculations, but they also use their experience to know what’s right.

What’s wrong with rule of thumb?

In the HVAC industry, do enough research and you’ll likely find people who will tell you the “rule of thumb” method is good enough. And many HVAC companies use the rule of thumb method rather than going through the trouble of working out the actual heating and cooling load calculations that are needed. This won’t ensure that the HVAC system you buy and install in your home is the optimal size for keeping your living space comfortable and energy efficient.

What’s your next step?

Find the right HVAC equipment for your home. When you’re ready to hire the best HVAC company for your needs, do some research and make some calls. Ask the right questions and you’ll have everything you need to make a well-informed decision.

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