Load Calculations: First Step before Selecting the HVAC Upgrade

When you’re selecting a new HVAC system for your home, the first critical step is conducting a load calculation. Your costs, long-term energy bills and comfort depend on getting the size right for your home. An HVAC contractor who skips this step and goes by the size of your existing equipment could be overlooking any changes or improvements made to your home to improve its energy efficiency.

Load calculations take into account the energy efficiency of your home, the amount of heat you and your family contribute to the conditioning load, along with its orientation to the sun. Contractors use software tools called Manuals J and D that take into account these factors:

• Cubic footage;
• Layout of your home;
• Insulation levels in the attic, walls and floor;
• Windows, their energy efficiency and orientation to the sun;
• Air infiltration rates;
• Heat-producing appliances indoors and your lighting types;
• Household members and their ages;
• Preferred indoor temperatures; and
• Landscaping factors.

Once the contractor has run the Manual J calculation to size the system, he or she moves onto the ductwork size and capacity using Manual D. It’s also important for the HVAC contractor to check your existing ducts and check for leaks or other problems. Proper duct design and tight sealing help the system run as efficiently as it was designed to do.

One of the biggest benefits of doing the load calculation first is that you learn how you can improve your home’s energy efficiency, which could result in a lower conditioning load. Anytime you can use a smaller system, you save money initially and each time it runs.

Systems that aren’t properly sized reduce your comfort. One that’s too large short cycles, driving up energy bills and leaving humidity behind in the summer. It starts and stops more often, which also increases the wear on all the parts. A system that’s too small won’t condition your home comfortably during weather extremes.

Please contact Stack Heating & Cooling to learn more about the importance of a load calculation. We’ve provided exceptional HVAC services for the greater Cleveland area since 1976.

Our goal is to help educate our customers in Cleveland, Ohio 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.

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