How Does an HVAC Professional Determine the Best Unit Size?

An improperly sized HVAC unit can cause many problems for home and business owners. An experienced professional considers multiple determining factors to estimate the size correctly. 

An improperly sized HVAC unit can cause many problems for home and business owners. People tend only to consider the square footage when calculating the size of their new HVAC system. In contrast, an experienced professional considers multiple determining factors to estimate the size correctly. 

Please keep reading to discover how an HVAC professional chooses the right unit size.

What happens if the HVAC unit is too small?

If the HVAC unit is too small, it will run non-stop to keep abreast of the space's temperature requirements. The continuous operation increases the energy consumption and, in turn, the electric bills. 

In addition, parts of the unit will overheat, and the unit will deteriorate faster than usual. Finally, a small unit will fail to adequately cool or heat the space, leading to discomfort even when running continuously.

What happens if the HVAC unit is too big?

Homeowners might think bigger units will regulate the temperature faster. Although this is partially correct, an oversized HVAC unit comes with its problems.

An HVAC unit that's too large for the space's ductwork will cause a short cycle, meaning the unit will turn on and off too frequently. The constant switching on and off will take a toll on the unit's parts, causing them to wear out faster.

Additionally, the larger the unit is, the more energy it uses to start up and shut down. Therefore, short cycling will cause a spike in the electrical bills.

A properly-sized HVAC system should also manage the humidity levels. If the installed unit is too big, the short periods between switching on and off won't be enough to extract the moisture from the air. Too much humidity can then lead to mold and unpleasant odors.

How to calculate the HVAC size correctly

The starting point for the calculation is the square footage of the residential or commercial space. As a rule of thumb, 600 feet of space require a 1-ton unit. However, many factors can influence this equation.

Therefore, when determining the correct unit size, an HVAC tech will also consider:

  • The number of residents, their age, and preferred temperatures

  • Insulation levels

  • Ductwork system efficiency 

  • The number of single and double-pane windows, their condition, and age

  • Sun and shade distribution 

  • Air leakage rate

  • The number of heat-generating appliances

  • Climate

Hire a professional

With so many factors to consider, it wouldn't be prudent to determine the proper size of an HVAC unit without a professional. A reputable HVAC company will have the necessary experience and knowledge to ensure the HVAC unit is the perfect fit for the space in question.

Fix My Air DFW of Fort Worth specializes in residential and commercial HVAC services including routine maintenance, installation, and repair. All makes/models. Call us at (817) 439-9811.

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