When you’re considering an HVAC system replacement, ask the contractor you hire to provide you with load calculations before selecting equipment. Learning the size of the system you need is crucial for it to operate at top efficiency and last as long as possible.

The load calculation takes into account a number of factors inside your home that contribute to the amount of heating or cooling required. Contractors use software called Manuals J and D to make the calculation, which factors in these elements:

  • Cubic footage
  • Location, size and efficiency of the windows
  • Insulation levels throughout your home
  • Floor plan design
  • The rate of air infiltration
  • Amount of heat you create indoors
  • Household size and ages of family members
  • Preferred indoor temperatures
  • Landscaping factors

Once these values have been entered, the first result will be the tonnage or BTUs (British thermal units) of the new system you need should be. Manual D addresses the size of the ductwork you need to distribute the conditioned air as evenly and efficiently as possible.

Choosing the wrong size system results in system inefficiency. Accurate load calculations help you avoid installing too large a system, which results in higher conditioning bills since HVAC equipment uses the most energy at startup, and increased wear and tear. Too large a system also will run brief cycles, drive up energy costs, and not dehumidify. The end result: your home won’t be as comfortable, since the areas further from the thermostat won’t have time to warm or cool as thoroughly. In the summer, the evaporator coil inside the air handler won’t remove as much humidity, either, since it doesn’t have time to chill completely.

A system that’s too small may not be able to keep you comfortable during weather extremes, particularly in the winter. You’ll have more airborne particulates because the air filter for the air handler won’t trap as many particulates.

To learn more about the value of load calculations, contact the pros at Comfort Systems, providing top-notch HVAC services for Wichita homeowners since 1996.

Our goal is to help educate our customers in Wichita, Kansas about energy and home comfort issues (specific to HVAC systems).  For more information about load calculations and other HVAC topics, download our free Home Comfort Resource guide.