What Size AC Unit Does My Home Need? A Homeowner's Guide to Load Calculations
True North Comfort SolutionsFounder, True North Comfort SolutionsJanuary 28, 20268 min read
Why Size Matters (More Than You Think)
One of the biggest mistakes in the HVAC industry is installing the wrong size system. And unfortunately, it happens more often than you'd think. Many companies use rough estimates or simply match the size of your existing unit -- even if the original was wrong.
What Is a Manual J Load Calculation?
A Manual J load calculation is the engineering standard for determining exactly how much heating and cooling your home needs. It factors in your home's square footage, insulation levels, window sizes and orientation, number of occupants, and local climate data. It's the only scientifically accurate method.
What Happens When Your AC Is Too Big
An oversized AC system is one of the most common problems we see. It cools the air quickly but shuts off before removing enough humidity, leading to a clammy, uncomfortable home. It also short-cycles, which puts enormous stress on the compressor and dramatically shortens system life.
What Happens When Your AC Is Too Small
An undersized system has the opposite problem -- it runs constantly trying to reach your set temperature, especially on the hottest Atlanta summer days. This leads to excessive wear, high energy bills, and rooms that never quite get comfortable.
How to Get It Right
The only way to get it right is with a proper Manual J calculation performed by a qualified technician. At True North, every system replacement starts with this calculation. We'd rather spend the extra time to get it right than install a system that's going to cause problems.
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Frequently Asked Questions
Can I just match the size of my current unit?
Not recommended. Many existing systems were improperly sized from the start. Changes to your home (new windows, insulation, additions) also affect sizing. A Manual J calculation is the only accurate method.
How long does a load calculation take?
A thorough Manual J calculation takes about 1-2 hours. It's a critical step that we include at no extra charge with every system replacement quote.
Ready to Take the Next Step?
Schedule your appointment and experience honest HVAC service.