Sizing & airflow
Manual J
The industry-standard load calculation that determines how much heating and cooling your specific home actually needs, using insulation, windows, orientation, ceiling heights, and air leakage, not just square footage.
Why it matters for your home
Manual J is the difference between equipment sized for your house and equipment sized for a rule of thumb. Oversized systems short-cycle and leave St. Louis homes clammy in summer; undersized ones can't keep up in January. If a quote names a system size without anyone measuring your home, ask how they got it, and get a second opinion before signing.
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