Air Conditioner Buying Guide: Sizing

In a climate like ours, getting central air conditioner sizing right is crucial for comfort and reasonable cooling bills. When a unit is too large or small, it won’t perform as well. Comfort diminishes, energy costs increase and the system won’t last as long.

There’s a lot to right sizing a cooling system.

It takes into account the size of the home, its overall energy efficiency, the floor plan design and the owner’s personal preferences for temperature levels. A competent HVAC pro will use Manual J software to calculate the best size for a home instead of going by the size of the existing cooling system.

Beware a contractor who skips the sizing process and goes by your existing unit.

If you or a previous owner have increased the energy efficiency of your home, you run the risk of installing a system that’s too large. It will run in short cycles that drive up energy costs, leave humidity behind and shorten the lifetime of your system. The secondary benefit from central air conditioners in this climate is humidity removal. Too much your home promotes mold growth and discomfort.

If your home has lost energy efficiency through insulation degradation, increased air leakage or aging windows, going by the existing unit instead of using careful air conditioner sizing techniques could result in too small an air conditioner. It won’t be able to keep up with the hottest weather that comes our way.

You’ll know if your contractor is conducting the load calculation for accurately sizing the air conditioner.

It involves:

• Window size, quality, quantity and placement
• Assessing attic and wall insulation levels
• Orientation of the home toward the sun
• Air infiltration rates
• Floorplan design
• Heat-producing appliances used indoors
• Family size and ages
• Personal preferences for temperature

Before you hire a contractor to install a new HVAC system, be sure that they will go through the sizing process at your home. It makes a difference in your home’s comfort, energy costs and the system performance.

To learn more about air conditioner sizing, contact CCAC, providing trusted HVAC services for Coastal Bend homeowners.

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 your HVAC system, download our free Home Comfort Guide or call us at 361-678-2495.