Everything You Need to Know About Load Calculations

Everything You Need to Know About Load Calculations

Everything You Need to Know About Load CalculationsNext time you’re in the market for a new furnace, A/C or heat pump, make sure your HVAC contractor properly sizes the system. If they’re just going to use old-school rule-of-thumb sizing methods (e.g., calculating heating or cooling system tonnage by inputting the home’s square footage), you’re liable to get an undersized or oversized system. Instead, your contractor should use modern load calculation software to compute your home’s heating load (or cooling load for air conditioning), then recommend a system size based that dovetails with that load calculation.

Why Exact Sizing is Important

The hazards of an undersized heating or cooling system are obvious. If the furnace or A/C lacks the capacity to properly condition all the rooms in your home, you’re losing out on comfort. Energy gets wasted, too, when a system is struggling 24/7 to condition a home.

Oversized equipment can be just as bad. It doesn’t take long to satisfy the thermostat temperature, and as a result the equipment is continually shutting off and turning back on (also known as short-cycling). This results in significant energy loss since HVAC equipment tends to use the most energy on startup. In addition, an oversized system can’t circulate air through whole-house filtration and humidity-control components as often, since it’s shutting down so frequently.

Both under- and oversized equipment tends to break down more often than properly sized HVAC systems.

How Does a Load Calculation Work?

A trained technician should use the Air Conditioning Contractors of America’s Manual J load calculation software. In computing your home’s heating or cooling load, Manual J takes into account multiple factors — including the home’s cubic footage, layout, window size and location, airtightness, insulation, climate and much more. The “load” is the amount of heat or cooling that’s needed to make the home feel comfortable. At this point, with the load calculation in hand, the technician will recommend the right-sized heating or cooling system for your particular home.

To discuss a new heating or cooling system for your Peachtree City area home, please contact us at Powers Heating & Air.


Our goal is to help educate our customers in Peachtree City, Georgia and surrounding areas about energy and home comfort issues (specific to HVAC systems). For more information about other HVAC topics, download our free Home Comfort Guide or call us at 770-487-2040.

Credit/Copyright Attribution: “clker-free-vector-images/Pixabay”

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