When you’re at the early stages of selecting a new HVAC system, be sure that you choose a contractor who includes load calculations as the first step.

These calculations assure you that the system you choose will be the right size for your home, including the size of the HVAC appliance and the ductwork. If one or both are improperly sized, your system may not reach its expected life or efficiency.

Contractors use software called Manuals J and D. Manual J calculates the size of the unit and Manual D addresses the ductwork design and size. These systems address the following factors about your home:

  • Cubic footage to condition
  • Insulation levels in the attic and walls
  • Number of windows, their efficiency, and orientation to the sun
  • Air infiltration rates
  • Layout of your home
  • Number of heat-producing appliances throughout the home and lighting types
  • Ages of household members and number
  • Preferred indoor temperatures
  • Landscaping factors

The contractor should carefully inspect your ductwork when doing the load calculations to verify that the system’s tight and adequately insulated. Depending on the size of the HVAC equipment you need, your ductwork may need to be modified to efficiently deliver the air.

When ducts are too small, they make noise and create back pressure on the blower. If they’re too large, the air won’t have the right velocity to reach your rooms efficiently.

The HVAC system itself needs to be the proper size, as well. If it’s too large, it will short cycle, which means it runs for short periods and turns on and off frequently. This drives up energy bills and creates excessive wear. Systems that are too small won’t be able to keep up with weather extremes.

Another benefit of conducting a load calculation is learning how improving your home’s insulation and sealing air leaks could reduce the size of equipment you need. Smaller systems have a lower cost and use less energy over time.

To learn more about load calculations, contact Fred’s Heating and Air. We’ve provided HVAC services for Omaha and Council Bluffs for more than two decades.