How to Size a New A/C System for Your Texas Home

The average A/C system lasts about 10 to 15 years. However, our warm Coastal Bend region demands more from our A/C systems than most areas in the country. If it’s time to install a new A/C system in your South Texas home, make sure your HVAC technician sizes it correctly.

Benefits of Sizing a New A/C System

Sizing a new A/C system is part science, part art form and, for an experienced HVAC technician, no guesswork at all. Unfortunately, many A/C systems (and furnaces) are oversized either for “good measure” or because the person is unaware of HVAC-industry best practices.

An oversized A/C cycles on and off frequently to reach and maintain peak cooling efficiency. Moreover, quick cycling also means your A/C won’t be able to adequately dehumidify your home. Higher indoor humidity makes the home feel warmer, which may prompt you to turn down the thermostat. Lowering your thermostat just one degree can increase energy consumption by 10 to 15 percent.  This rapid cycling is also very inefficient for the operation of the air conditioner.

On the flip side, an A/C that’s sized too small won’t be able to handle the cooling and dehumidification demand in South Texas.

A/C Sizing to the Letter

HVAC-industry best practices for system sizing is outlined and determined by Manuals J and S, which is created by the Air Conditioning Contractors of America (ACCA) organization.

• Manual J: Manual J is used to determine the cooling (and heating) load of your home. Dozens of factors are considered, such as window number and size, sun orientation, number of occupants, schedules, insulation values, air sealing quality and more. An A/C is not only sized by the square footage of your home.
• Manual S: Manual S uses the numbers from Manual J to properly size and select the A/C that’s best for your home and needs. Considerations for add-on equipment and advanced features, such as zoning systems and variable-speed air handlers, are factored into the equation too.

If you’re shopping for a new A/C system to install in your Coastal Bend home, make sure the A/C is sized and selected correctly. Please contact CCAC today for professional results.

Our goal is to help educate our customers in Corpus Christi, Texas about energy and home comfort issues (specific to HVAC systems). For more information about sizing a new A/C and other HVAC topics, download our free Home Comfort Resource guide.

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